Accelerated stability testing


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Accelerated stability testing

  2. 2. CONTENTS Introduction Activation energy Arrhenius equation Accelerated stability testing Limitations of accelerated stability testing ICH guidelines 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, microbiological, 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 economical repercussion.7. Essential quality attribute. 4
  5. 5. ACCORDING TO USP TYPES OFSTABILITYType Condition to be maintained1.Chemical : Chemical integrity & lebelled potency2.Physical: Appearance, palatability, uniformality.3.Microbiological Sterility4.Therapeutic: Drug action remains unchanged 55.Toxicological: No increase in toxicity
  6. 6. ACTIVATION ENERGY:It is defined as the energy that must be overcome in order for achemical reaction to occur. Activation energy may also be definedas the minimum energy required to start a chemical reaction.The activation energy of a reaction is usually denoted by Ea, andgiven in units of kilojoules per mole. 6
  7. 7. ARRHENIUS EQUATION :Arrhenius equation gives "the dependence of the rate constantk of chemical reaction on the temperature T (in absolutetemperature, such as Kelvin or degrees Rankine) and activationenergy Ea", as shown below: (1) Where k=specific rate constant A=frequency factor Ea= activation energy R=ideal gas constant T=absolute temperatureTake 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 7
  8. 8. Estimation of k:1.Reaction is conducted at several temp.2.Conc. is determined at different time period.3.Order of reaction is identified.4.From slope of line k is calculated. Fig. Estimation 8
  9. 9. ESTIMATION OF ACTIVATION ENERGY: A graph can be drawn by taking log k on y-axis and reciprocal temperature (1/T) on x-axis. A straight line is obtained, the slope of the line is negative and the magnitude is Ea /2.303 R. The intercept corresponds to log A. All the constants in the Arrhenius equation can be obtained from the graph. 9 Fig. estimation of activation energy
  10. 10. Calculation of shelf life:ORDER X axis Y axis HALF LIFE SHELF LIFEZERO Time (a-x) a/2k 0.1A0/K0FIRST Time log(a-x) 0.693/k 0.105/K1SECOND Time 1/(a-x) 1/ka -(a=b)SECOND Time Log b(a-x)/a 1/ka -(a≠b) (b-x)THIRD Time 1/(a-x)2 3/2ka2 -
  11. 11. TYPES OF STABILITY TESTS: Long term stability tests Field test Accelerated stability testsAccelerated 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. 11
  12. 12. 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 12 Desert zone 30˚c/35%RH
  13. 13. TESTS AT HIGH INTENSITY OF LIGHT: Drug substances fade or darken on exposing to light, can be controlled by using amber glass or opaque container. By exposing drug substance to 400 & 900 (FC)of illumination for 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 diffused reflectance spectroscopy for examination. e.g. cycloprofen becomes very yellow after five days under 900 foot candles of light. 13
  14. 14. TESTS AT HIGH PARTIAL PRESSURE OF OXYGEN: Sensitivity of the drugs to atmospheric oxygen must be evaluated from which it should be packed in inert atmospheric condition with antioxidants is decided . 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 14 condition .
  15. 15. 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. 15
  16. 16. LIMITATIONS OF ACCELERATEDSTABILITY 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 • Photochemical reactions • Diffusion • Excessive agitation When the product looses its physical integrity at higher temperatures. When the order changes at elevated temperatures. 16
  17. 17. STABILITY PROTOCOL: Containers and closures Container orientation Sampling interval Type, size and number of batches Plan of sampling Storage conditions Test methodology Acceptance criteria 17
  18. 18. ICH GUIDELINES ON STRESS TESTING:Standard Title and referenceICH Q1A(R2) Stability Testing of New Drug Substances and Products (the parent guideline)ICH Q1B Photostability Testing of New Drug Substances and ProductsICH Q C Stability testing of new dosage formsICH D Bracketing and matrixing designsICH Q E Evaluation of stability dataICH Q F Stability data package for registration 18 applications in climatic zone I and IV
  19. 19. REFERENCES Patrick J.Sinko , Martin’s Physical Pharmacy and Pharmaceutical Sciences. Theory and practice of Industrial Pharmacy – Lachman International Stability Testing Drug stability- Cartensen C.V.S. Subrahmanyam 19
  20. 20. THANK YOU… 20
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