1. Stability testing of drugs and pharmaceuticals
factors influencing media effects and pH effects
PRESENTED BY
M. ROHITHA REDDY
ROLE NO:256213886021
M.PHARMACY (PHARMACEUTICS)
UNDER THE GUIDENCE
OF
MRS. YASMIN BEGUM
2. Contents
Drug stability
Criteria for Acceptable Levels of Stability
Applicable guidelines
Climatic zones
Role of stability testing
Stability Testing - API
Stability testing - FPP
Factors influencing media effects
pH
3. Drug stability
Stability of drug also can be defined as the time from the date
of manufacture and packaging of the formulation until its
chemical or predetermined level of labelled potency and its
physical characteristics have not changed appreciably.
4. Criteria for Acceptable Levels of Stability
Type of Stability Conditions Maintained Throughout the Shelf Life of
the Drug Product
Chemical Each active ingredient retains its chemical integrity and
labeled potency, within the specified limits.
Physical The original physical properties, including appearance,
palatability, uniformity, dissolution and suspend ability are
retained.
Microbiological Sterility or resistance to microbial growth is retained
according to the specified requirements. Antimicrobial
agents that are present retain effectiveness within the
specified limits
Therapeutic The therapeutic effect remains unchanged
Toxicological No significant increase in toxicity occurs.
5. Applicable guidelines
WHO „Guidelines for stability testing of pharmaceutical products
containing well established drug substances in conventional dosage
forms”
WHO working document QAS/05.146 - Stability Studies in a Global
Environment.
ICH guidelines Q1A-Q1F. Stability testing of new APIs and FPPs has
been harmonized at global level.
6. Selected definitions
Re-test date
The date after which samples of an API should be examined to ensure
that the material is still in compliance with the specification and thus
suitable for use in the manufacture of a given FPP.
Shelf life (expiration dating period, conformance period)
The time period during which an API or a FPP is expected to remain
within the approved shelf-life specification, provided that it is stored
under the conditions defined on the container label.
7. Selected definitions
Stress testing – forced degradation (API)
Studies undertaken to elucidate the intrinsic stability of the API. Such
testing is part of the development strategy and is normally carried out
under more severe conditions than those used for accelerated testing.
Stress testing – forced degradation (FPP)
Studies undertaken to assess the effect of severe conditions on the
FPP. Such studies include photo stability testing (see ICH Q1B) and
compatibility testing on APIs with each other in FDCs and API(s)
with excipients during formulation development.
8. Selected definitions
Accelerated testing
Studies designed to increase the rate of chemical degradation or
physical change by means of exaggerated storage conditions.
Intermediate testing
Studies at 30degC/60%RH, intended for extrapolation to long term
storage at 25degC [provided that 25degC is appropriate for the
market in question]
Stress testing
API: Studies which elucidate intrinsic stab of API. Normally
during development. Normally more stressful than ‘accelerated’
testing.
Finished product: Studies of effect of ‘severe’ conditions. Eg
freeze/thaw cycling for suspensions & emulsions, low humidity for
aqueous liquids in moisture-permeable containers.
9. In-use stability testing:
Establishes the “period of time during which a multidose product
can be used while retaining quality within an accepted
specification once the container is opened”
For example:
• liquids that are reconstituted prior to use
• effervescent tablets in a moisture-proof container (eg Al
screw-cap tube)
• ophthalmic products (especially with respect to
preservative efficacy)
10. Long term stability testing conditions are determined by the
climatic condition under which the API is intended to be
stored.
Zone I: temperate 21◦C/45%RH
Zone II: subtropical/mediterranean 25◦C/60%RH
Zone III: hot/dry 30◦C/35%RH
Zone VIa: hot/humid (Kenya) 30◦C/65%RH
Zone VIb: hot/very humid 30◦C/75%RH
11. Role of stability testing
Provides evidence on how the drug substance or product quality
varies with time under environmental conditions during distribution.
Helps to recommend storage conditions including establishment of
shelf life, expiry date or retest period.
Key assurance of quality of pharmaceuticals.
13. ICH guidelines on stress testing
Q1A (R2) : Stability testing of new drug
substance and new drug product
Q1B : Photo stability testing
Q1C : Stability testing of new dosage forms
Q1D : Bracketing and Matrixing for stability testing
of new drug substance and new drug product
Q1E : Evaluation of stability data
Q1F : Stability data package for the registration
applications of climatic zones
Q5C : Stability testing of
biotechnological/biological products
14. STRESS TESTING
Helps to identify the likely degradation products and
establish degradation pathways and intrinsic stability of
molecule.
Carried out on single batch.
Effect of temperature ( every 100 C)
Humidity
15. Stress testing
To identify potential degradants (degradation pathways) of
the API and assess if they can be formed during manufacture
or storage of the FPP (intrinsic stability of the API).
To validate the stability indicating power of the analytical
procedures.
To identify stability-affecting factors such as ambient
temperature, humidity and light and to select packing
materials, which protect the FPP against such effects.
No standard method for testing.
16. Stress testing (forced degradation)
Degradation factor Conditions
Thermal ≥ 60 oC
Humidity ≥ 75% RH
Acid 0.1N HCl
Base 0.1N NaOH
Oxidative Oxygen gas, or 3% H2O2
Photolytic Metal halide, Hg, Xe lamp, or UV-B fluorescent
Metal ions (optional) 0.05M Fe2+ or Cu2+
17. Stress testing
Temperature
A thin layer of the API is wetted with water
and is kept at 80°C for 4 weeks in a Petri
dish (open system) with sampling once a
week
Assay:
S1:
D1:
Total unspecified:
Total impurities:
Humidity
A thin layer of the API is wetted with water
and kept at 40°C / 100% RH for 4 weeks in
a Petri dish (open system) with sampling
once a fortnight
Assay:
S1:
D1:
Total unspecified:
Total impurities:
Oxidation
Oxygen is bubbled slowly through the
oxygen-saturated aqueous
solution/suspension (under constant mixing)
of the API for 24 hours with sampling every
eight (8) hours
Assay:
S1:
D1:
Total unspecified:
Total impurities:
18. Prequalification experience
Results Comments
Deceptive Degradation level is good (<15%) but no
relevant degradants are observed
Predictive Degradation level is good (<15%) and at
least one or all relevant degradants are
observed
Useless Between 15 and 100% degradation but no
relevant degradants observed
19. Requirements for predictive stress conditions
Recommendations in Supplement 2:
Should lead to the degradation of the main compound, but not
more than 5-15%.
Should lead to a good predictability of degradation pathways
(i.e., a low probability of "drastic" or "false" degradation)
Should be conducted for no longer than three months.
20. Stress testing of API in solution
Storage conditions Testing period*
pH ± 2, room temperature 2 weeks
pH ± 7, room temperature 2 weeks
pH ± 10-12, room temperature 2 weeks
H2O2, 0.1-2% at neutral pH,
room temperature
24 hours
* Storage times given or 5-15% degradation, whatever comes first
21. Stress stability testing
An optimal degradation pattern generated during stress testing
would show only those degradation products observed at the
end of shelf life in regulatory stability studies and those that
might appear if the API or FPP if not manufactured, handled or
packed properly.
Chromatograms thus obtained will be representative and not
too complicated to evaluate, which may be the case if drastic
conditions are applied and many second- and third-generation
degradation products are formed.
22. Increase in concentration of API
• During stability studies of Artesunate, the assay results were
increasing. The hydrolysis may yield artenimol and succinic
acid. The latter can justify the increase in assay. The assay
method is”stability indicating” but not specific.
+ +
23. Regulatory or formal stability testing
Storage temperature
(°C)
Relative
humidity
(%)
Minimum time
period covered
by data at
submission
(months)
Accelerated: 40±2 75±5 6
Intermediate: 30±2 65±5 12
Long term: 25±2 60±5 12 (6)
25. Stability Room
1. A special cabinet for each
condition
2. Design, construction,
qualification, monitoring
3. Costs of operation including
R & D failures
4. Time
26. Stability results
A storage statement should be proposed for the labeling (if
applicable), which should be based on the stability evaluation
of the API.
A re-test period should be derived from the stability
information, and the approved retest date should be displayed
on the container label.
An API is considered as stable if it is within the
defined/regulatory specifications when stored at 30±2oC and
65±5% RH for 2 years and at 40±2oC and 75±5%RH for 6
months.
28. Potential instability issues of FPPs
Loss/increase in concentration of API
Formation of (toxic) degradation products
Modification of any attribute of functional relevance
Alteration of dissolution time/profile or bioavailability
Decline of microbiological status
Loss of package integrity
Reduction of label quality
Loss of pharmaceutical elegance and patient acceptability
29. Stability-indicating quality parameters
Stability studies should include testing of those attributes of the
FPP that are susceptible to change during storage and are likely to
influence quality, safety and/or efficacy. For instance, in case of
tablets:
♦ appearance ♦ hardness
♦ friability ♦ moisture content
♦ dissolution time ♦ degradants
♦ assay ♦ microbial purity
30. Selection of Batches
At the time of submission data from stability studies should be
provided for batches of the same formulation and dosage form
in the container closure system proposed for marketing.
Stability data on three primary batches are to be provided. The
composition, batch size, batch number and manufacturing date
of each of the stability batches should be documented and the
certificate of analysis at batch release should be attached.
Where possible, batches of the FPP should be manufactured by
using different batches of the API.
31. Significant Change of FPPs
• A 5% change in assay from its initial value.
• Any degradation product exceeding its acceptance criterion.
• Failure to meet the acceptance criteria for appearance, physical
attributes, and functionality test (e.g., color, phase separation,
hardness).
• As appropriate for the dosage form, e.g., failure to meet the
acceptance criteria for dissolution for 12 dosage units.
32. Factors influencing media effects and pH
Temperature
Primary factor affecting the drug stability.
To study the effect of temperature on reaction, it is necessary
to study decomposition of product at elevated temperature.
Help in predicting stability of product at ordinary temperature.
33. It catalyses hydrolysis, oxidation and thermal reaction
Method for expressing the influence of temperature on
reaction proposed by Arrhenius:
K = A * e-Ea/RT
Where K= specific rate of degradation
A= Frequency factor
Ea = Arrhenius Activation Energy
R= Gas constant
T= Absolute temperature
34. Logarithmically it can be expressed as:
Log K = log A - Ea/ 2.303 RT
From the graph of K 1/T one can determine Ea from slope
and A from intercept.
35. Limitations of Arrhenius relationship for prediction
of stability of products
At higher temperature evaporation of solvent takes place and
thus changes in concentration.
At higher temperature change in solubility and humidity
(decreases) which cannot be correlated with room temperature.
For disperse systems at higher temperature viscosity decreases
which can change physical characteristics resulting in
potentially large errors in prediction of stability.
Different degradation mechanisms may predominate at
different temperatures thus making stability prediction
difficult.
36. Humidity
Higher humidity may leads to moisture adsorption.
Drugs which are highly sensitive to hydrolysis
Relative humidity Stability
increase decrease
Higher humidity increases ageing process through interaction
of drugs with excipients.
37. Effect of solubility
Applicable to drugs in solution form.
Eg:- Penicillin are very unstable in aqueous solution because
of hydrolysis of β-lactum ring.
Ways for stabilization
Stabilized by using insoluble salts of API.
Formulate the drug in suspension dosage form.
38. Effect of ionic strength
The rate of reaction can be influenced by the ionic strength of
the solution in accordance with the following equation:
log k = log k0 + 1.02ZA ZB √U
Where,
ZA and ZB = charges carried by the reacting
species in solution
U = the ionic strength
K = rate constant at infinite dilution.
Where,
U = ½Σ CZ2
39.
40. Drugs with
Positive charge:
Undergoes H+ ion catalysis and increase in ionic strength
caused by the addition of salt increases rate of reaction.
Neutral charge:
Ionic strength will have no effect.
Negative charge:
Undergoes OH- ion catalysis and increase in ionic
strength caused by the addition of salt decreases rate of
reaction.
41. pH
By changing 1 pH unit , there is change in more than
10 fold in rate constant.
Before formulating drug in solution, K vs pH should
be studied and optimum pH at lowest value of rate
constant is to be found.
Hydrogen ion catalysis occurs at lower pH
Hydroxyl ion occurs at higher pH.
42. References
1) E.A.Rawlins, Bentley’s Textbook of Pharmaceutics,Bailliere Tindal(2004),
8th edition, page no-140.
2) Jens T. Carstensen, Drug stability, Marcel Dekker, 2ndedition.
3) Patrick J. Sinko, Martin’s Physical Pharmacy & Pharmaceutical sciences,
Lippincott Williams & Wilkins, 4th edition, Page No.:397.
4) Leon Lachman,Herbert A.Lieberman,Joseph L. Kanig,The theory &
Practice of Industrial Pharmacy, Warghese Publication House(Mumbai),3rd
edition, Page No.:171.
5) Gilbert S. Banker & Christopher T. Rhodes, Modern Pharmaceutics,
Marcel Dekker(New York), 4th edition.
6) Alfonso R. Gennaro, Remington: The science & Practice of Pharmacy,Vol-
1,Lippincott Williams & Wilkins, 20th edition-2000,Ch-41, Page No-780.
7) pharmaceutical preformulation and formulation by Mark Gibson
