    

W

HI

  

W

1
1

{IHHIWHMNWlNIHWNIHMIW

    

"lwé
INN
(1)0100

lllll

 

 

 

 

 

 

 

 

"IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

IIII’iIII

LIBRARY
Michigan State
University

 

 

 

 

This is to certify that the

thesis entitled

DISSOLUTION SHELF-LIFE OF UNPACKAGED SOLID
ORAL DRUG PRODUCTS

presented by
Sheau-shya Wu
has been accepted towards fulﬁllment

of the requirements for

MASTER' 3 degree in PACKAGING

 

 

1M 8 adj/LAW

Major professor

Date 0W é, f??6

 

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

PLACE N RETURN BOX to romavothb chockomtmn your noord.
TO AVOID F INES return on or baton dd. duo.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MSU loAn Afﬂnnativo Action/Equal Opportunity Institution

 

 

 

 

 

 

 

 

 

 

DISSOLUTION SHELF-LIFE OF UNPACKAGED SOLID ORAL DRUG
PRODUCTS

By

Sheau-shya Wu

A THESIS

Submitted to
Michigan State University
in partial fulﬁllment of the requirements
for the degree of

MASTER OF SCIENCE

School of Packaging
1996

ABSTRACT
DISSOLUTION SHELF-LIFE OF UNPACKAGED SOLID ORAL DRUG PRODUCTS
By

Sheau-shya Wu

If the relationship between drug dissolution, storage temperature and humidity
were known, it would be easy to select the best materials for stability testing and
marketing. The dissolution characteristics of one drug product have been determined.
This information will allow selection of packages for the drug product. The drug product
was Axid (N izatidine capsules) provided by Eli Lilly.

The Axid capsules were stored at three temperatures (18°C, 28°C and 38°C) with
nine relative humidities (12, 22, 33, 44, 50, 63, 75, 80, and 90% RH). The capsules were
stored unpackaged, in open dishes. Samples were taken at 6 days and then at 30 day
intervals for dissolution testing. Dissolution vs. relative humidity isotherms were
obtained for Axid stored at the three temperatures and nine relative humidities for ninety
days. Several dissolution failure points were identiﬁed, and a shelf life for unpackaged
Axid was determined.

The dissolution stability of Axid (N izatidine) was greatly reduced when capsules
were stored at 38°C and around 75% RH. Therefore, the critical relative humidity inside
the package could be identiﬁed as 75% RH. The dissolution stability was found to be

reduced at 28°C, 80 and 90% RH as well.

This thesis is dedicated to my lovely parents

Meng-hua Wu and Zing- tsu Wu

iii

ACKNOWLEDGMENTS

Many people provided guidance and encouragement to me over the last two years
as the work in the thesis progressed. I would like to take this opportunity to acknowledge
some of them.

Certainly Professor Hugh Lockhart deserves special thanks for the timely
direction and support that he has provided me over the years. Professor Lockhart’s ability
to quickly identify the important issues associated with a problem has always motivated
my studies. Although his dedication to teaching and research in the ﬁeld of
pharmaceutical packaging keeps him very busy, he is always able to ﬁnd time for
discussions with his students. Finally, equally important as his outstanding academic and
administrative abilities is his easygoing and subtly witty personality. Working with him
was exceeding stimulating, often intense, but always enjoyable.

In addition, I would like to thank Dr. Sue Selke and Dr. Gililland for their prompt
and thoughtful discussion of this thesis. Each individual provided expertise and valuable
input regarding the research required for this area of study. The many students, both past
and present, have provided much help to me during my time at Michigan State.
Speciﬁcally, I want to thank X. Qian, M. Kokitar, K. Tanprasert and K. T. Feng for their

academic advice and friendship over the years. Jay Lyle Chick deserves special thanks.

iv

He has had no choice but to provide answers as I chased him around the department with
my persistent questions for the last six months.

It was a privilege to work with the Center for Food and Pharmaceutical Packaging
Research at MSU. I am grateful for the ﬁnancial support and continued interest in this
project. I deeply appreciated all of the materials and information supplied by Eli Lilly
Company, as well, for use in this research area.

Finally, and most importantly, I want to thank Mr. and Mrs. Wu, my father and
mother. Throughout my life, their encouragement and guidance have always served to
point me in the right direction. And I would like to thank my family for their continued

love and support during my prolonged absence from Taiwan.

TABLE OF CONTENTS

LIST OF TABLES ..................................................................................................... vii
LIST OF FIGURES ..................................................................................................... ix
1. Introduction .............................................................................................................. 1
2. Literature Review .................................................................................................. 4
2.1 Dissolution ......................................................................................................... 4
2.2 Factors Inﬂuencing the Dissolution Stability of Solid Oral Products ............... 5
2.2.1 Formulation Variables .............................................................................. 6
2.2.2 Binders and Disintegrants Factors ............................................................ 6
2.3 Effect of Temperature and Relative Humidity on Gelatin Capsules ................. 7
2.4 Effect of Aging .................................................................................................. 7
2.5 Dissolution and Storage Conditions .................................................................. 8
2.6 Effect of Packages on Dissolution ................................................................... 10
3. Experimental Materials and Methods ..................................................................... 12
3.1 Materials and Equipment .............................................................. . ................... 12
3.2 Dissolution Methodology ................................................................................. 12
3.3 Storage Condition ............................................................................................. 14
3.4 Storage Exposure ............................................................................................... 14
3.5 Sample Intervals ................................................................................................ 15
3.6 Dissolution Isothenn ......................................................................................... 15
4. Results ..................................................................................................................... 17
5. Conclusions ............................................................................................................. 32
Appendices .................................................................................................................. 35
Bibliography ............................................................................................................... 42

vi

LIST OF TABLES

Table 1. Equilibrium relative humidities for saturated salt solutions ............................... 16
Table 2. An example AN OVA table for capsules stored at 18°C and 38°C for 6 days
by SAS system analysis ....................................................................................... 35
Table 3. Results of AN OVA for temperature effect on 30 minutes dissolution at 18°C
and 38°C by SAS analysis (P-values < 0.05 considered signiﬁcant) .................. 36
Table 4. Results of ANOVA for RH effect on 30 minutes dissolution at 18°C by SAS
analysis (P-values < 0.05 considered signiﬁcant) ............................................... 36
Table 5. Results of AN OVA for RH effect on 30 minutes dissolution at 28°C by SAS
analysis (P-values < 0.05 considered signiﬁcant) ............................................... 37
Table 6. Results of AN OVA for RH effect on 30 minutes dissolution at 38°C by SAS
analysis (P-values < 0.05 considered signiﬁcant) ............................................... 37
Table 7. The effect of storage conditions on 30 minutes dissolution of Axid capsules at
38°C (the dissolution value was the average of three capsules) ......................... 38
Table 8. The effect of storage conditions on 30 minutes dissolution of Axid capsules at
28°C (the dissolution value was the average of three capsules) ......................... 38
Table 9. The effect of storage conditions on 30 minutes dissolution of Axid capsules at

18°C (the dissolution value was the average of three capsules) ......................... 39

vii

Table 10. Results of AN OVA for RH and storage time effect on 30 minutes dissolution
at three different temperatures by SAS analysis (P-values < 0.05 considered

signiﬁcant) ........................................................................................................ 39

viii

LIST OF FIGURES

Figure 1. Initial dissolution proﬁle of three Axid capsules .............................................. 22
Figure 2. Dissolution proﬁle of three capsules aﬁer storage at 75% RH and 38°C for 32-
34 days ............................................................................................................... 23
Figure 3. The effect of RH on 30 min dissolution of capsules after storage at 18°C ....... 24
Figure 4. The effect of storage time on 30 min dissolution of capsules after storage at
18°C (below 60% RH) ...................................................................................... 25

Figure 5. The effect of storage time on 30 min dissolution of capsules after storage at

18°C (above 60% RH) ...................................................................................... 26
Figure 6. The effect of RH on 30 min dissolution of capsules after storage at 28°C ...... 27
Figure 7. The effect of RH on 30 min dissolution of capsules aﬁer storage at 38°C ...... 28

Figure 8. The effect of storage time on 30 min dissolution of capsules aﬁer storage at
38°C (below 60% RH) ...................................................................................... 29

Figure 9. The effect of storage time on 30 min dissolution of capsules after storage at
38°C (above 60% RH) ...................................................................................... 30

Figure 10. The effect of three different temperatures on 30 min dissolution of capsules

stored at 75% RH ........................................................................................... 31

ix

Chapter 1

INTRODUCTION

Currently, in the pharmaceutical industry, a major concern lies in the dissolution
shelf life of solid oral drug products. To determine which packaging materials will prevent
moisture interactions with product from adversely affecting a product throughout its shelf
life is very important. It is necessary to know the expiration date of a drug product, and the
expiration date is based on chemical, and physical characteristics of the drug product as
well as upon estimates of the bioavailability of the active ingredient.

Product development research includes the estimation of expiration date based upon
early research, and storage under accelerated conditions. This estimation is based on
information about the kinetics of the chemical reaction or reactions that lead to degradation
of the drug product. These predictions measure the loss, or change in concentration, of the
active ingredient in the drug product.

Bioavailability of the active ingredient in the drug product has become a major
factor in evaluation of the expiration date. Bioavailability refers to the ability of the drug
product to release the active ingredient into the gastro-intestinal tract after ingestion.
Bioavailability is affected not only by chemical changes in the drug, but also by physical
changes in the drug product that affect the release of the active ingredient. For tablets,

hardness, disintegration, and dissolution are drug product characteristics that affect the

2
degree of bioavailability of the active ingredient from the drug product. For capsules,

solubility of capsule, disintegration of capsule contents and dissolution affect
bioavailability. Changes in these characteristics are physical changes. They are not
described by the kinetic equations used for the chemical properties of the drug.

Dissolution has been accepted by the United States Pharmacopeial Convention as a
measure of bioavailability and as a stability indicating parameter for solid oral drug
products. It is measured by a standard method published in the United States
Pharmacopoeia (U SP.) and dissolution limits are speciﬁed in the USP. monographs for
most solid oral drug products. The US Food and Drug Administration (FDA) requires that
any drug product on the market must at all times meet the requirements of the USP
monograph. If it fails to do so, the product is subject to recall action. During the last year
there have been 16 recalls of solid oral drug products because of failure to meet USP
dissolution requirements.

The speciﬁc objectives of this study are listed below :

1. To measure the dissolution value of a solid oral product using USP standard methods for
several time periods at different storage conditions

2. Plot the values for dissolution at the 30 minute time point in the dissolution proﬁle,
because the 30 minutes dissolution value is the USP requirement for the drug product
under study.

3. To use statistical methods to analyze for signiﬁcant differences in dissolution for capsules
stored at three different temperatures and nine humidities.

4. To use the above information to generate dissolution isotherms for the product.

3
5. To identify dissolution failure points on the isotherm.

6. To determine if dissolution as an endpoint indicator of shelf life can be used in shelf life

prediction for solid oral drug products.

Chapter 2

LITERATURE REVIEW

2.1 Dissolution

Many drug products should be protected from temperature and humidity changes to
maintain acceptable product quality throughout their shelf life. There has been a
considerable increase in the interest in physical aging of capsules, or dissolution value of
capsules (Hoblitzell et al., 1985)

Dissolution stability of a drug product may be deﬁned as the maintenance of the
dissolution characteristics of the product from the time of manufacture up to the expiration
date. Release of a drug from the dosage form into the gastrointestinal ﬂuids is an essential
ﬁrst step in drug absorption and bioavailability, so dissolution is a critical parameter in
determining the performance and deﬁning the quality control, regulatory compliance, and
impact on the bioavailability of solid oral products. Signiﬁcant changes in the in-vitro
release proﬁles of a drug product during storage may indicate a change in bioavailability.
Formulation components (active drug, excipients, and coating materials), processing
parameters, storage conditions, and packaging are all factors that can alter the dissolution
stability of a product during aging.

A drug product may undergo changes in physico-chemical characteristics that can

alter the bioavailability of the dosage form during storage. Important physico-chemical

5
parameters that decide the quality of the preparation and that are susceptible to change

during aging include appearance, chemical assay, degradation product level, moisture
content, dissolution rates, and for tablets, hardness, ﬁ'iability (and disintegration times).

The dissolution proﬁles of an oral solid product can impact the rate and the amount of drug
available for absorption and therefore may affect the therapeutic efficacy of the product.
When a product is stored under the conditions speciﬁed on the label, it is expected that the
product will retain its initial dissolution proﬁles throughout its shelf-life. One of the reasons

for product recalls is failure to meet dissolution speciﬁcations during storage (Murthy and it

Ghebre-Sellassie, 1 993).

2.2 Factors Inﬂuencing the Dissolution Stability of Solid Oral products

Primary among these are the six factors; manufacturing processes, formulation
variables (e.g., physico-chemical properties of the active and inactive components), in-
process controls, dissolution method, storage conditions, and packaging. In nearly all
situations, the result is controlled by more than one factor. Therefore, the effects are
difﬁcult to outline by the particular factors alone. For instance, the effect of adverse storage
conditions on drug release may be intensiﬁed by poor packaging. On the other hand,
effective protective packaging can improve the stability of a product during aging. Any one
of the four factors, formulation variables, processing factors, packaging, and storage

conditions acting alone or in concert can inﬂuence the product shelf-life.

2.2.1 Formulation Variables

During storage, dissolution stability of a solid oral drug product is closely
connected to the qualitative and quantitative composition of the formulation. There are
some analytical parameters such as the solubility, hygroscopicity, and thermal properties of
the active component and excipients, including coating materials, which have apparent
impact on the result of dissolution stability. For example, the active drug may dissolve and
recrystallize and in the process change the release properties of tablets during storage under
high humidity conditions. Furthermore, a tablet may absorb or lose moisture and harden,
thus changing the disintegration properties of the dosage form, depending on the storage
conditions. The effect of moisture and heat on the integrity of the coating on tablets mainly
affects the dissolution stability of the product. Generally, enteric- and sugar-coated products
are more sensitive to the effects of humidity than uncoated or ﬁlm-coated products.
Consequently, formulation variables, ﬁllers, disintegrants, binders, and coating materials are

decisive to the maintenance of the dissolution stability of the dosage form.

2.2.2 Binders and Disintegrants Factors

Binders and disintegrants have opposing roles in a tablet formulation. Since a
binder in a tablet formulation is to provide the necessary adhesion and bonding between
particles, disintegrants are added to facilitate the dividing of the tablet mass, to increase the
surface area, and thus promote dissolution. These two components of a tablet formulation
should be chosen together because decrease in the dissolution rate of the product during
storage due to binder effect can sometimes be overcome by the inclusion of a proper

disintegrant.

2.3 Effects of Temperature and Relative Humidity on Gelatin Capsules

The effects of storage time and relative humidity on the disintegration and in-
vitro drug release of 4 brands of chloramphenicol capsules has been studied (Khalil et al.,
1974). At 49% and 66% RH no obvious change in either disintegration or drug release
occurred for storage periods up to 32 weeks. The drug suffered nearly total decrease in drug
release due to the failure of the gelatin shell to disintegrate when stored at 80% RH. Drug
release was slightly increased after storage at 100% RH. Nevertheless, the gelatin shells
were rubbery, soft and difﬁcult to handle.

A signiﬁcant decrease in the amount of chloramphenicol released due to impaired
disintegration was the result when the capsules were stored at 80% RH. In contact with the
dissolution medium, the gelatin shell which was rubbery showed a considerable swelling
and failed to dissolve within one hour. It is difficult to reﬂect the exact changes which
might have occurred in the gelatin shell upon storage at 80% RH, but it is probable that
cross linking occurred at this RH and caused changes in the dissolution property. This was
given by Khalil et al.(1974) as the reason that the gelatin shell was rubbery and appeared to

swell but did not dissolve.

2.4 Effects of Aging

Environmental conditions such as relative humidity have a considerable effect on
the active substances in their various dosage forms, and this effect can be reﬂected in the
bioavailability of the drug. During storage, this might be revealed as a decrease or loss in

therapeutic effectiveness. The release rate determination of the active substance just after

8
preparation might not be an absolute reﬂection of the release pattern of the drug after aging

storage (Akbuga et al., 1984).

2.5 Dissolution and Storage Conditions

Although formulation and process variables are mainly determinants of the in-vitro
drug release of capsule products at the time of their manufacture, storage conditions
signiﬁcantly affect the stability of these preparations and inﬂuence their dissolution proﬁles
during aging.

Gelatin is water-soluble at 37°C (Clark and Courts, 1977). The insolubility of
gelatin that resulted from storing the capsules under stress conditions was probably caused
by a polymerization process involving cross-linking and hydrogen bonding (Marks et al.,
1968). A number of reagents that promote such cross-linking have been identiﬁed. These
include aldehydes, sulfuric acids, hydrogen peroxide, and glucose. Speciﬁc interactions can
occur between carboxyl and amino groups of gelatin and the various ﬁrnctional groups of
the dyes involving ionic, hydrogen, and van der Waal's bonding, leading to an irreversible
denaturation reaction. These reactions presumably are facilitated by UV or visible
inadiation under high-humidity conditions. Dissolution changes were occurring in capsule
products under accelerated conditions of storage depending on the storage conditions, the
colorants present in the capsule shell, the aqueous solubility of the drug substance involved,
and the test procedures used to measure drug dissolution.

Signiﬁcant changes in drug-release patterns were observed with colored capsules

only under the combined inﬂuence of high humidity and intense UV or visible radiation.

9
The plastic bottles and caps typically used to store and dispense pharmaceutical products

would afford a high degree of protection against humidity and light. Nevertheless, the
ﬁndings of this study have shown that storage conditions can play a signiﬁcant role in the
stability of these products and in their drug dissolution proﬁles over time.

Accelerated stability evaluation of hard-shell capsule products has shown that drug
dissolution rates can be impaired by storage under high-stress conditions. For example, the
denaturation of gelatin causes changes to occur in the conformational properties and
solubility properties of the capsule shell (Murthy et al., 1989).

Another study found that the dissolution stability of hard gelatin capsule (HGC)
products is decided by the moisture content of the shell, and this moisture content is related
to the storage conditions. Gelatin is the main component of the capsule shell which is a
heterogeneous mixture of polypeptides. The shells of HGC normally contain ~ 13.0-16.0%
water and can be safely stored between 40 and 60% RH. Variations within the range 12.0-
18.0% moisture do not seriously inﬂuence the integrity of the shell. Below ~12% water, the
shell becomes brittle and is easily split. Above 18% moisture, the shell is moist, soft, and
deformed with a propensity to transmit moisture to the capsule contents if the contents are
hygroscopic (Murthy and Ghebre-Sellassie, 1993). Such a situation seems to prevail when
the ﬁlled capsules are stored in high humidity environments. The contents will become
moist and form a cake which may dissolve poorly.

During storage, changes in the dissolution characteristics of the capsule products
occur due to either a physico-chemical change in the basic structure of the capsule shell or a

change in the properties of the capsule contents. One of the effective ways of preventing

10
moisture n'ansfer from the capsule shell to the capsule contents is to equilibrate each of the

shell and the capsule blend, separately to the same relative humidity (e.g., 40-60% RH) so
that no transfer of moisture happens to and from the shell (Murthy and Ghebre-Sellassie,

1993)

2.6 Eﬁ'ect of Packages on Dissolution

The role of packaging in dosage form design is to serve as a barrier to moisture
transfer from the environment to the enclosed product and to protect the product from the
effects of heat and oxygen. Packaging cannot protect the product from the effects of heat.
Packaging has been accorded a lower priority relative to formulation activities and storage
conditions in the design and development of dosage forms. Although packaging
development is considered to lie outside the mainstream of product development, it is a
main element that controls the result of dissolution stability during storage and should be
treated as an integral part of developing stable and effective pharmaceutical products.

One consideration in the selection of packaging materials is the retention of identity,
strength, quality, and purity of the given drug product for the duration of its shelf life. The
formulation should retain the dissolution characteristics of the product during normal
storage conditions. The use of proper packaging materials usually provides an extra element
of protection for the product; the degree of protection afforded is dependent on the nature of
the packaging materials used, including the permeation characteristics, and the environment
in which the product is stored (Murthy and Ghebre-Sesllassie, 1993).

The effects of packaging and storage in multiple-unit and unit-dose containers on

dissolution rate of model prednisone tablets were reported by Taborsky-Urdinola et

l l
al.(1981). USP Prednisone Dissolution Calibrator Tablets were packaged in three multiple-

unit and ﬁve unit-dose containers. Packaged tablets were stored for three to six months
under three conditions: 40°C, 85% relative humidity (RH); 37°C, 75% RH; and 22°C, 75%
RH. Dissolution rate was measured at pre-determined intervals during storage. For each
condition tested, two separate runs of six tablets each were performed. Tablets in the least
moisture-permeable containers were least affected by storage. The conditions of high heat
and humidity caused the greatest change in dissolution rate. When stored at 22°C and 75%
RH, little change in dissolution rate occurred in any packaged tablets (T aborsky-Urdinola et
al., 1981).

The practical importance of packaging, and storage under controlled conditions was
described. Proper packaging and storage are essential to maintain product integrity. The
permeability of the container is critical in situations where the product is to be subjected to
less desirable conditions, arbitrarily those in excess of 22°C and 75% RH. (T aborsky-

Urdinola et al., 1981).

Chapter 3

EXPERIMENTAL MATERIALS AND METHODS

3.1 Materiak and Equipment

1. Axid (Nizatidine) Capsules, 150 mg, Lot 7CT 31 from Eli Lilly

2. VK 7000 Dissolution Test Station (V anKel, VANKEL INDUSTRIES, INC.)

3. P-5000, 1 mL Pipetteman; 1 mL and 5 mL polypropylene pipette tips (from Rainin)

4. Cotton (from Target)

5. 5 mL disposable plastic syringe for sampling

6. Sampling tube- An 8 inch length of plastic tubing of 0.16 inch diameter. Conton is
packed into about 1 inch length at one end of the tube to act as a ﬁlter. A 5 mL syringe is
attached to the tube at the ﬁlter and of the tube to draw the sample from the dissolution
vessel. The cotton ﬁlter serves to remove drug product particles that could interfere with
the light beam in the spectrophotometer (Qian, 1996).

7. Spectrophotometer Lambda 3 (Perkin Elmer) for absorbance measurements

8. SAS system (Version 6.0) for statistical analysis

3.2 Dissolution Methodology

W The testing was performed using a USP paddle

apparatus in 900 mL of deionized, deaerated water at 373°C. The water is the dissolution

12

13

medium. The sample size for this experiment was three capsules for each condition. A
vinyl coated paper clip was attached to a capsule (on the yellow cap) to allow the capsule to
sink to the bottom of the vessel before rotation of the blade is started. The paddle rotation
speed was 50 rpm. The procedure ran for 50 minutes. With the sampling tube and 5 mL
syringe 2-3 mL sample was taken at 5, 10, 20, 30, 40, 50 rrrinutes from the middle of each
vessel. The sarnpling solution was ﬁltered by the cotton in the sampling tube. So, the
solution was transparant and clean. Then the sample was put into a plastic bowl. Using a 1
mL Pipetteman with 1 mL pipette tip, a 0.4 mL sample was drawn from the bowl. The
ﬁltered sample was diluted to 20 fold with deionized water, and the absorbance of the

diluted sample at 314 nm in the spectrophotometer.

WW3 To determine the amount of Nizatidine dissolved,
absorbances at the wavelength of maximum absorbance for Nizatidine at about 314nm was
used. The raw readings will use 48.96 ml/mg of USP Standard Nizatidine concentration
(the slope of calibration curve) to calculate the concentration and dissolution value of
samples. This information is then used to plot curves which represent the dissolution proﬁle

of a product.

[I l l . .
% dissolved = (Abs/S) x n x V/W x 100

where S: slope of the calibration curve for Nizatidine, 48.96 ml/mg
n: dilution fold of the sample, 20 times

V: volume of the dissolution medium in the vessel, 900 ml

14
W: the amount of the Nizatidine in each capsule, 150 mg

SH] l'

The SAS system (Version 6.0) was used to analyze the dissolution data by 2-way
and 3-way AN OVA (analysis of variance). The 30 min dissolution data reported in Tables
7-9 were obtained by averaging the dissolution results of three separate capsules. Then, the
30 min dissolution value was utilized to run the General Linear Models Procedure and
results were summarized in an AN OVA table. Signiﬁcant differences (p-values < 0.05)
were detected for storage times, humidity, and temperature; which indicated the dissolution

rate of capsules is a function of these parameters (SAS/STAT User’s Guideline).

3.3 Storage Conditions

The three temperatures used were 18°C, 28°C, and 38°C in order to cover the entire
temperature range the product is likely to encounter. At each temperature, nine humidity
levels were used, sampling from 12% RH to 93% RH. The hurrridities are shown in Table 1.
The humidity buckets were prepared by placing nine different saturated salt solutions into
tightly closed 5 gal plastic containers. Calibrated hygrometer sensors were installed in each
bucket to monitor the humidity values. Hurnidities were measured at 0, 3, and 6 months.

The dissolution test was determined at four different storage times - 6, 30, 60 and 90 days.

3.4 Storage Exposure
The capsules were stored in open dishes in the buckets. They were not in any
package. Therefore this experiment found the response of the capsule product t o the

humidity at each temperature.

l 5
3.5 Sampling Intervals

Samples of stored capsules were removed for dissolution testing at intervals of 6,

30, 60 and 90 days.

3.6 Dissolution Isotherm
Because of the open dish exposure of the capsules, the resulting data represent
dissolution/RH isotherms for the Axid capsules. This is analogous to the moisture isotherm

used for moisture sensitive foods and other products.

16

Table 1. Equilibrium relative humidities for saturated salt solutions at three temperatures

 

Percent Relative Humidity at Stated Temperatures

 

 

 

 

 

 

 

 

 

 

Saturated Salt Solution 13°C 28°C 38°C
Egrliuérzrghloride 16.10 12.10 1420
2:33:33: Acetate 22.50 2200 23,60
mgegig Chloride 36.75 32.50 3 535
2:23:11; 2((2)arbonate 45.75 43.75 4450
right: NM“ 67.00 64.00 63.25
Eligirm Chloride 74.70 7520 75.70
Ammlggigfr Sulfate 79.20 30.00 3020
gmgjium Nitrate 92.80 91.00 39.30

 

 

 

 

 

Note: The humidity values in the table are the actual values measured, veriﬁed after 30 and
60 days storage. In reporting, these values may be rounded to 2 places, and grouped
into categories.

Chapter 4

RESULTS

Figures 1 and 2 show typical dissolution proﬁles. Figure 1 is the proﬁle for Axid
capsules as manufactured, and for any time during their shelf life when no deleterious
changes have taken place. This proﬁle was generated for ﬁesh capsules stored at room
temperature in a high density polyethylene bottle in a desiccator. Drug release was quick
from the fresh capsules, and almost all of the drug was in solution within 30 min. The
differences in the amount of drug dissolved at the initial sampling time of 5 min. were
caused by small differences in the dissolution times of the capsules. Figure 2 shows a
dramatic change in the proﬁle that has taken place after 32-34 days at equilibrium with 75%
RH and 38°C. Note that the 30 minute dissolution has been reduced from 95% dissolved to
about 50% dissolved. USP requires 75% dissolved, so this product is headed for a shelf life

problem.

11' l . I 1
Figures 3, 6, and 7 describe the dissolution isotherms for Axid capsules at three
temperatures and four different time intervals. The 30 min dissolution is used because it is
the one speciﬁed in the USP monograph for Nizatidine (Axid). The SAS system analysis
(2-way and 3-way AN OVA) results show that temperature, storage time, and relative

humidity will affect the dissolution values (p-values < 0.05) (Table 10). The percent drug

17

18
dissolved has signiﬁcant differences for four different storage time intervals at high

temperature (38°C) and high relative hurrridities (75% and 80% RH). At 28°C and 75% RH,
there is a signiﬁcant difference in drug dissolved after 90 days. At three different
temperatures, the dissolution values have small, but signiﬁcant differences at 6 and 90 days

storage in different relative humidities.

D' l . 18° C

Figures 4 and 5 show the time effect for dissolution of Axid at 18°C. The 30 min.
dissolution values did not change much over the whole testing range of relative humidities
during 90 days storage. There is a signiﬁcant difference (p-values < 0.05) in dissolution
value of capsules after storage at 93% RH for 90 days. The dissolution value decreased
from about 100% to 90%. The information has helped establish the length of time that
capsule products can be exposed at 93% RH before detectable changes occur in their
dissolution rates. There is no change in dissolution of the product until the 90th day. So, the
result showed that the time effect may occur at a higher humidity, and after a longer time.

There is no change in appearance of capsules at 18°C.

D' l . 28°C

Figure 6 describes the dissolution isotherm for Axid at 28°C at four time intervals.
Capsules stored at higher relative humidity (75%-90% RH) for 30 days are soft and sticky.
They would fail on that without doing a dissolution test. Note that there is no loss of
dissolution at any relative humidity through 60 days. By 90 days, note the progressive loss

in dissolution at 75% RH. The product has failed sometimes between 60 and 90 days.

19
When coming into contact with the dissolution medium (deionized water), the aged

capsules swelled and formed a partially insoluble gelatin shell. A swollen, rubbery, gelatin
shell which enveloped the encapsulated powder, was observed during the dissolution
testing. The capsule shell broke up so Slowly, that powder release through this gelatin shell
was rate-limiting for the dissolution process. This effect was apparent in the capsules tested
at the end of three months of storage at 75% RH (Figure 6). Drug dissolution was reduced

under this storage condition; only about 65% of the drug was in solution after 30 min.

B. l . 38° C

The combined effect of high temperature and humidity on the dissolution
performance of stored capsules is exhibited in Figure 7. Note the progressive loss in
dissolution at 75% RH. The product has failed before 30 days. The capsules became soft
and sticky when they were stored at high humidity (75-90% RH). So, they are failed
samples. Capsules stored at 75% and 80% RH, were rubbery, forming a big bubble during
the dissolution testing. The bubble trapped the powder, and this ballooning phenomenon
resulted in a lower dissolution value.

Notice the behavior at 90% RH. The product seems to lose dissolution, then regain
it. However, this does not mean the product becomes usable again. At 90% RH, the
capsules were sticky, soft, and fell apart because the gelatin has absorbed so much water.
The crucial roles played by moisture and heat in affecting the conformational properties of
gelatin and rendering it insoluble are clearly evident from the 30, 60 and 90 day points on
the graph at 75% RH and 80% RH. About 62% of the drug was dissolved at 75% RH and

about 68% of drug was dissolved at 80% RH (Table 7). Delayed disintegration of the

20
capsule shell was the primary reason for the slow release of drugs. As time goes on, the

dissolution value decreases under storage at 75% RH and 80% RH. After storage for three
months, only about 15% of drug dissolved at 75% RH and 49% of drug dissolved at 80%
RH (Table 7). The aged capsules showed a huge effect on drug dissolution (p—values < 0.05)
when stored at 75% RH at the high temperature (Table 6). There was some delay in the
disintegration of these capsules, and a big, insoluble gelatin ﬁlm was observed during the
dissolution experiments, suggesting that heat and humidity accelerates the reaction leading
to the denaturation and cross-linking of gelatin.

Figures 8 and 9 present the results of the effect of storage time on the dissolution
proﬁle of the capsules after storage at 38°C. The dissolution value decreases with longer
storage time at higher relative humidities. Figure 8 shows dissolution after storage below
60% RH at 38°C. There are no signiﬁcant changes in dissolution over time. Figure 9
presents the effect of storage time on the dissolution proﬁle of capsules after storage above
60% RH at 38°C. There were apparent effects on the dissolution proﬁle of stored capsules
at 75% RH and 80% RH (p-values < 0.05) (Table 6). When capsules were stored at 90%
RH and high temperature (3 8°C) for three months, there was no apparent change from
initial dissolution patterns. The aged capsule shell dissolved rapidly and exposed the
powder bed, which subsequently broke up, resulting in rapid drug dissolution (Figure 7).
However, the capsules stored at 90% RH were not usable because they were sticky and soft.
They had failed before doing the dissolution test. Therefore the appearance of “return to

initial dissolution” is a false positive.

21
Figure 10 describes the effect of temperature on the dissolution proﬁle of capsules

after storage at 75% RH. The dissolution value decreased more when capsules were stored
at 38°C for longer time. The lower temperature (18°C) does not seem to affect the
dissolution value of stored capsules. There was no apparent change ﬁorn initial dissolution
patterns to be seen during the dissolution experiments. Capsules stored at 90% RH, at all
three temperatures, stuck together, and some of them were already broken before doing

dissolution testing. These are failed samples even before doing the dissolution test.

% Drug Dissolved

120

22

 

 

 

 

Time (min)

+ Sample 1. + Sample 2. -A- Sample 3.

Figure 1. Initial dissolution proﬁle of Axid capsules. It is the typical
dissolution proﬁle for three Axid capsules as manufactures, and for any
time during their shelf life when no deleterious changes have taken place.
Drug release was quick from the fresh capsules, and almost all of the drug
was in solution within 30 min.

 

% Drug Dissolved

120

23

 

 

 

 

Time (min)

+ Sample 1. + Sample 2. -A— Sample 3.

Figure 2. Dissolution proﬁle of capsules after storage at 75% RH and 38°C
for 32-34 days. Notice that the 30 min dissolution has been reduced from
95% dissolved to 50% dissolved.

 

% Drug Dissolved

120

20

24

 

 

 

 

%RH
+ 6-8 days + 32-34 days 4— 62-64 days —a— 92-94 days

Figure 3. The effect of RH on 30 min dissolution of capsules after storage
at 18°C. There is no change in appearance of capsules at 18°C. The 30 min
dissolution values did not change much over the whole testing range of
RH during 90 days storage.

 

% Drug Dissolved

120

80 _.

20

25

 

 

 

 

lb Rf 1b

8

Time (days)
+16.10%RH + 22.50%RH 4— 36.75 %RH -a- 45.75 %RI-I -0— 551!) %RH

Figure 4. The effect of storage time on 30 min dissolution of capsules after
storage at 18°C (below 60% RH).

 

% Drug Dissolved

26

 

120

1%..

20..

 

 

 

 

2a a: a: a;
Time (days)
+ 67%RH + 74.7%RH -A- 79.2%RH —a— 92.8%RH

Figure 5. The effect of storage time on 30 min dissolution of capsules after
storage at 18°C (above 60% RH).

 

27

120

 

 

 

 

100,. I
A
lri

Io 80-

0

>

"S

In

coll

D 60-

go

.\° 40.
20.
0 10 w W W

 

 

 

%RH
+ 6-8 days + 32-34 days -A- 62-64 days -a— 92-94 days

Figure 6. The effect of RH on 30 min dissolution of capsules after storage
at 28°C.

% Drug Dissolved

120

20

28

 

 

 

 

 

%RH
+ 6-8 days + 32-34 days -A- 62-64 days -a— 92-94 days

Figure 7. The effect of RH on 30 min dissolution of capsules after storage
at 38°C. Note the progressive loss in dissolution at 75% RH. The product
has failed before 30 days.

 

% Drug Dissolved

120

100

80-

20

29

 

 

 

 

 

 

20 lb RI TSP
Time (days)
+14.2%RH + 23.60%RH -A— 35.25%RH -a— 44.50%RH + 53.75%RH

Figure 8. The effect of storage time on 30 min dissolution of capsules after
storage at 38°C (below 60% RH).

 

% Drug Dissolved

120

30

 

80

20

 

 

 

 

w w RI Sb
Time(days)
+ 63.25%RH + 75.7%R1-1 -A- 80.20%RH -a— 89.80%RH

Figure 9. The effect of storage time on 30 min dissolution of capsules after
storage at 38°C (above 60% RH). The capsules stored at 90% RH were not
usable because they were sticky and soft. They were failed before doing
the dissolution test.

 

% Drug Dissolved

120

100

80.

20

31

 

 

 

 

 

 

:\ + a— _'
+
:0 W 60* —8b
Time (days)
+18°C+ 28°C-*- 38°C

Figure 10. The effect of temperature on 30 min dissolution of capsules
stored at 75% RH for 90 days. The lower temperature (18°C) does not
seem to affect the dissolution value of stored capsules.

 

Chapter 5

CONCLUSIONS

Signiﬁcant changes in drug-release patterns were observed only under the combined
inﬂuence of high humidity, storage time and heat. Increased understanding of these factors
Should help in developing better capsule formulations and packaging that will maximize
dissolution over the shelf life of the capsules, and thereby maximize the bioavailability of
the medicament throughout the shelf life of the capsules.

The results obtained from the experiment allow us to draw the following three
conclusion about Axid:

1) Axid has a critical relative humidity for dissolution that is between 60% RH and 75%
RH. Dissolution failure is extensive at 75% RH, but minimal at 60—63% RH.

2) Axid has a critical temperature for dissolution that is between 18° C and 28°C.
Dissolution failure has been observed at 28° C but not at 18° C. Dissolution failure is
catastrophic at 38° C.

3) Dissolution response (time to failure) is affected by interactions among time, temperature
and relative humidity.

a) In this experiment, dissolution decreased with increasing time of exposure at

both 75% and 80 % RH, and the rate of change was greater at 75% than at 80%.

(See Figure 9).

32

33
b) At 75% RH and 38° C, dissolution failure occurred by the 30th day of storage,

while at 75% and 28° C dissolution remained within USP limits (Figure 9).

c) At 75% RH, 28° C, dissolution decreased Sharply from day 60 to day 90, while at
38°C the rate of dissolution loss was less. In fact, the slope of dissolution loss at
28° C between day 60 and 90 may be about the same as the slope for 38° C
between day 6 and day 60. The 38° C slope from day 60 to day 90 is less than
either of them (Figure 10).

The dissolution results obtained for Axid suggest that for solid oral drug products,
there is a product speciﬁc dissolution function that can be related to temperature, relative
humidity and time of exposure to a relative humidity at a temperature. The Axid evidence
suggests that the time to dissolution failure goes down as temperature and relative humidity
goes up. Furthermore, it seems the temperature and relative humidity interact to exacerbate
the deleterious effect of either one alone.

If a dissolution/temperature/relative humidity function can be determined, then that
function can be used in a mathematical model, to calculate the time to dissolution failure for
packaged product. The dissolution function, along with permeability constants for the
package and temperature and relative humidity of storage will be the input to the model,
and time to dissolution failure will be the output.

Such calculations are not likely to replace stability testing. However, they can be
used to select the packages in which to put product for stability test. The advantage would
be: 1) rapid selection of package. 2) greater certainty that the package chosen will provide

the protection needed.

34
For future work --

1. Use existing shelf life equations and computer models to predict the shelf life of Axid,
modify as needed.
a. Calculate dissolution rate, k, and dissolution rate reduction constant, K.
b. Determine a mathematical function for dissolution similar to those used for
moisture content.
c. Detennine permeability constants for candidate packaging materials.
2. Use the relationship among temperature, dissolution, and moisture content to construct a

tirne-at-temperature and relative humidity equation to model the dissolution shelf life.

APPENDICES

APPENDIX A

Table 2. An example ANOVA table of capsules stored at 18°C and 38°C for six days by
SAS system analysis. The RH value was 63%. From this result, the temperature

will affect the dissolution value of capsules (p = 0.001). (p-values < 0.05
considered signiﬁcant)

The SAS System

General Linear Models Procedure

Dependent Variable: DISSOLVE

Source DF Sum of Squares Mean Square F Value Pr > F
Model 3 156.84117500 52.28039167 11.19 0.0001
Error 32 149.49910000 4.67184687
Corrected Total 35 306.34027 500

R-Square C.V. Root MSE DISSOLVE Mean
0.511984 2.206889 2.161444555 97.94083333

Source DF Type I SS Mean Square F Value Pr > F
TEP 1 145.08202500 145.08202500 31.05 0.0001

CAPSULE 2 1 1.75915000 5.87957500 1.26 0.2978

35

APPENDIX B

Table 3. Results of AN OVA for temperature effect on 30 minutes dissolution at 18°C and
38°C by SAS analysis (p-values < 0.05 considered signiﬁcant). The RH value

 

 

 

was 63%.

Source Storage Time p-values Signiﬁcant
Difference

Temp 6 0.0831 NS.

30 0.3280 NS.

60 0.0551 NS.

90 0.0689 N.S.

Capsules 6 0.3636 NS.

30 0.0383 S.
60 0.2061 NS.
90 0.2638 N.S.

 

 

 

 

Table 4. Results of ANOVA for RH effect on 30 rrrinutes dissolution at 18°C by SAS
analysis (p-values < 0.05 considered signiﬁcant)

 

 

 

Source Storage Time p-values Signiﬁcant
Difference
RH 6 0.0376 S.
30 0.7658 N. S.
60 0.0003 S.
90 0.0001 S.
Capsules 6 0.0340 S.
30 0.4300 N. S.
60 0.5960 N. S.
90 0.1069 N. S.

 

 

 

 

 

 

36

APPENDIX C

Table 5. Results of ANOVA for RH effect on 30 minutes dissolution at 28°C by SAS
analysis (p-values < 0.05 considered signiﬁcant)

 

 

 

 

 

 

Source Storage Time p-values Signiﬁcant
Difference
RH 6 0.0001 S
90 0.0001 S.
Capsules 6 0.7832 N. S.
90 0.5853 N. S.

 

Table 6. Results of ANOVA for RH effect on 30 minutes dissolution at 38°C by SAS
analysis (p-values < 0.05 considered signiﬁcant)

 

 

 

 

 

 

Source Storage Time p—values Signiﬁcant
Difference
RH 6 0.0001 S.
30 0.0001 S.
60 0.0001 S.
90 0.0001 S.
Capsules 6 0.8809 N. S.
30 0.9351 N. S.
60 0.9196 N. S.
90 0.3264 N. S.

 

37

 

 

APPENDIX D

Table 7. The effect of storage conditions on 30 minutes dissolution of Axid capsules at
38°C (the dissolution value was the average of three capsules)

 

 

 

% RH 6 - 8 days 32 - 34 days 62 - 64 days 92 - 94 days
14.20 101.3 96.7 91.3 95.3
23.60 99.8 99.2 91.6 94.6
35.25 97.2 98.1 91.4 98.0
44.50 100.5 98.5 92.3 96.8
53.75 102.2 100.1 95.0 94.4
63.25 98.7 96.1 95.3 97.4
75.70 100.0 62.4 26.2 15.4
80.20 98.2 67.5 59.3 48.8
89.80 96.7 88.3 92.7 94.1

 

 

 

 

 

Table 8. The effect of storage conditions on 30 minutes dissolution of Axid capsules at
28°C (the dissolution value was the average of three capsules)

 

 

 

% RH 6 - 8 days 32 - 34 days 62 - 64 days 92 - 94 days
12.10 91.4 - - 93.2
22.00 94.8 - - 93.9
32.50 97.4 98.7 92.6 91.8
44.00 - - - -
51.50 95.6 98.9 92.6 92.8
64.00 96.8 95.0 94.1 98.3
75.20 96.2 94.3 91.7 64.5
80.00 98.6 97.7 96.7 98.6
91.00 97.7 93 .6 89.9 98.4

 

 

 

 

 

Note: - No sample from these conditions

38

 

 

APPENDIX E

Table 9. The effect of storage conditions on 30 minutes dissolution of Axid capsules at
18°C (the dissolution value was the average of three capsules)

 

 

% RH 6 - 8 days 32 - 34 days 62 - 64 days 92 - 94 days
16.10 96.3 97.6 98.6 93.8
22.50 96.1 98.6 99.2 96.6
36.75 96.7 96.7 98.9 96.9
45.75 96.1 96.2 97.1 96.9
55.00 95.8 98.0 95.6 96.5
67.00 97.4 98.2 98.5 99.2
74.70 96.6 97.8 97.8 98.9
79.20 98.4 96.5 91.3 99.8
92.80 98.0 97.9 99.2 90.2

 

 

 

 

 

 

 

Table 10. Results of AN OVA for RH and storage time effect on 30 minutes dissolution at
three different temperatures by SAS analysis (p-values < 0.05 considered

 

 

 

signiﬁcant)
Source p—values Signiﬁcant Difference
Temp 0.0001 S.

Day 0.0001 S.

RI-I 0.0001 S.
Temp*Day 0.0001 S.
Temp*RH 0.0001 S.

Temp*Day*RH 0.0001 S.

 

 

 

39

 

APPENDIX F

Nizatidine (from USP monograph)

C12H21N50282 331.47

* Nizatidine contains not less than 98.0 percent and not more than 101.0 percent of
C12H21N502Sz, calculated on the dried basis.

Packaging and storage - Preserve in tight, light-resistant containers.

USP Reference standards < 11 > - USP Nizatidine RS.

Nizatidine Capsules

* Nizatidine Capsules contain not less than 90.0 percent and not more than 110.0 percent
of the labeled amount of C12HerstSz.

Packaging and storage - Preserve in tight, light-resistant containers. Store at controlled

room temperature.

USP Reference standards < 11 > - USP Nizatidine RS.

Identiﬁcation -

A: Empty the contents of 2 Capsules into a beaker, add 20 mL of methanol, and swirl for

approximately 2 minutes. Filter through a ﬁlter paper, and evaporate the methanol

solution with a current of cool air to dryness : the infrared absorption spectrum of a

potassium bromide dispersion of the residue so obtained exhibits maxima only at the

same wavelengths as that of a similar preparation of USP Nizatidine RS.

40

41

B: The retention time of the major peak in the chromatogram of the Assay preparation
corresponds to that of the Standard preparation, both relative to the internal standard, as

obtained in the Assay.

Dissolution < 711 > -

Medium: water; 900 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Procedure-- Determine the amount of C12H21N502Sz dissolved from ultraviolet
absorbances at the wavelength of maximum absorbance at about 314 nm using ﬁltered
portions of the solution under test, diluted with water if necessary, in comparison with a
Standard solution having a known concentration of USP Nizatidine RS in the same
medium.

ToleranceS-- Not less than 75% (Q) of the labeled amount of c,,H,,N,o,S, is dissolved in

30 minutes.

BIBLIOGRAPHY

BIBLIOGRAPHY

Akbuga, J., Ari-Ulubelen, A., and Bayraktar-Alpmen, G., “ Effect of Relative Humidity on
Drug Release from Phenytoin Sodium Tablets and Capsules, Part 1: Commercial
Preparations,” Pharmazie, 39:560-561. 1984.

Clark, R. C. and Courts, A., “ The Chemical Reactivity of Gelatin,” in The Science of
Technology of Gelatin, Ward, A. G. and Courts, A., Eds. (Academic Press, New York,
1977), Pp. 209—247.

Hoblitzell, J. R., Thakker, K. D., Rhodes, C.T., “ Effects of Moderate Stress Storage
Conditions on the Dissolution Proﬁle of Enteric-coated Aspirin Tablets, ” Pharm. Acta.
Helv., 60:28-32, 1985.

Khalil, Saleh A. H., Ali, L. M. M., and Khalek, M. M. Abdel, “ Effects of Aging and
Relative Humidity on Drug Release, Part 1: Chloramphenicol Capsules, “ Pharmazie, 29:
36-37, 1974.

Khalil, S. A. H., Barakat, N. S., and Boraic, N. A., “ Effects of Package Type on In Vitro
Release and Chemical Stability of Amoxycillin in Capsules,” Pharm. Ind., 53:698-701,
1991.

Marks, E. M., Tourtellotee, D., and Andux, A., “ A Phenomenon of gelatin Insolubility,”
Food Technol. 22, 1433-1436, 1968.

Murthy, K. S., Enders, N. A., and Fawzi, M. B., “ Dissolution Stability of Hard-Shell
Capsule Products, Part I: The Effect of Exaggerated Storage Conditions, “ Pharmaceutical
Technology, pp. 72-86, March 1989.

Murthy, K. S. and Ghebre-Sellassie, Isaac, “ Current Perspectives on the Dissolution
Stability of Solid Oral Dosage Forms,” J. of Pharmaceutical Sciences 82: 113-126, 1993.

42

43

Qian, X. “Dissolution Stability for Packaging Application,” M. S. Thesis, Michigan State
University, 1996.

SAS/STAT User’s guide, SAS Institute, Inc. Version 6.0. Fourth Edition, vol 2: pp969-972,
1996.

Taborsky-Urdinola, C. 1., Gray, Vivian A., and Grady, Lee T., “ Effects of Packaging and
Storage on the Dissolution of Model Prednisone Tablets, “ Am. J. of Hospital Pharmacy,
38: 1322-1327, 1981.

The United States Pharmacopoeia 23, Dissolution < 711 >, pp1094-1095, 1995.

MICHIGAN STATE UNIV. LIBRRRIES
II I II III III IIlI III IIIIII |I| I|II II IIIIII IIII IIII IIII II IIII I II
31293015655016