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  2. 2. CONTENTS  Introduction  Activation energy  Arrhenius equation  Accelerated stability testing  Limitations of accelerated stability testing  References 2
  3. 3. INTRODUCTION  Stability: Stability of pharmaceutical product may be defined as the capability of a particular formulation in a specific container/closure system to remain within its physical, chemical, therapeutic and toxicological specification. 3
  4. 4. Need for stability testing: 1. Provide evidence as to how the quality of the drug product varies with time. 2. Establish shelf life for the drug product. 3. Determine recommended storage conditions. 4. Determine container closure system suitability. 5. Safety point of view of patient. 6. Prevention of expenses. 7. Essential quality attribute. 8. To save time and money. 4
  5. 5. Types of Stability Type Condition to be maintained 1.Chemical : Chemical integrity & lebelled potency 2.Physical: Appearance, uniformality. 3.Microbiological Sterility 4.Therapeutic: Drug action remains unchanged 5.Toxicological: No increase in toxicity 5
  6. 6. ACTIVATION ENERGY: It is defined as the energy that must be overcome in order for a chemical reaction to occur. Activation energy may also be defined as the minimum energy required to start a chemical reaction. The activation energy of a reaction is usually denoted by Ea 6
  7. 7. ARRHENIUS EQUATION : Arrhenius equation gives "the dependence of the rate constant k of chemical reaction on the temperature T and activation energy Ea", as shown below: Where k=specific rate constant A=frequency factor Ea= activation energy R=ideal gas constant T=absolute temperature 7 Take log on both sides, ln k = ln A –Ea/RT ln e (2) Converting eq. 2 to log 10 log k = log A – Ea/2.303RT (1)
  8. 8. TYPES OF STABILITY TESTS:  Long term stability tests  Accelerated stability tests  Stress study Accelerated stability studies: Studies designed to increase the rate of chemical degradation or physical change of an active substance or drug product by using exaggerated storage conditions as part of the formal, definitive storage programme. 8
  9. 9. Tests at elevated temperature:  Drug liquid preparation stored at 50, 60, 70,85,100 and 121˚c.  Also study performed at R.T. and or refrigerator temp.  Sampling: First year- 3 month interval Second year- 6 month interval  Four climatic zones: Temperate zone 21˚c/45%RH Mediterranean zone 25˚c/60%RH Tropical zone 30˚c/70%RH Desert zone 30˚c/35%RH 9
  10. 10. Tests at high intensity of light:  Drug substances darken on exposing to light, can be controlled by using amber glass or opaque container.  By exposing drug substance to 100& 121(fc)4 & 2 weeks to light and another sample examined protected from light .  Results found on appearance and chemical loss may be recorded.  Comparing color or using spectroscopy for examination.  e.g. cycloprofen becomes very yellow after five days exposing to light. 10
  11. 11. Tests at high partial pressure of oxygen:  Here, high oxygen tension plays important role to investigate stability Usually ,40% of oxygen atmosphere allows for rapid evaluation.  Results were correlated with inert & without inert condition . 11
  12. 12. Tests at high relative humidity:  Presence of moisture may cause hydrolysis and oxidation.  These reactions may accelerated by exposing the drug to different relative humidities.  Control humidity by Lab desiccators  Closed dessicator are placed in an oven to provide constant temperature. 12
  13. 13. LIMITATIONS OF ACCELERATED STABILITY TESTING  Valid only when the break down depends on temperature.  The energy of activation obtained in the study should be between 10 to 30 kcal/mole.  It is not useful when degradation is due to: • Microbial contamination • Diffusion • Excessive agitation  When the product looses its physical integrity at higher temperatures.  When the order changes at elevated temperatures. 13
  14. 14. ICH GUIDELINES ON STRESS TESTING: Standard Title and reference ICH Q1A(R2) Stability Testing of New Drug Substances and Products (the parent guideline) ICH Q1B Photostability Testing of New Drug Substances and Products ICH Q C Stability testing of new dosage forms ICH D Bracketing and matrixing designs ICH Q E Evaluation of stability data ICH Q F Stability data package for registration applications in climatic zone I and IV 14
  15. 15. REFERENCES  Martin’s Physical Pharmacy and Pharmaceutical Sciences. Patrick J.Sinko ,  Theory and practice of Industrial Pharmacy – Lachman  International Stability Testing Drug stability- Cartensen  Textbook of Physical Pharmaceutics C V S Subrahmanyam Vallabh Prakashan 15
  16. 16. THANK YOU… 16
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