Kinetics of degradation 1 Flashcards
what is drug stability
the ability of a drug to maintain physical, chemical, toxicological, microbial and therapeutic properties during the time of storage and usage by patient
what is shelf life?
The time during which the medicinal product is predicted to remain fit for intended use under specified conditions of storage.
Time from manufacture / preparation until original potency or content of active ingredient has been reduced by 10% [t10 or t90] which is the limit of chemical degradation
Stability testing important in
Provide evidence on how the quality of a drug substance or drug product varies with time under the influence of a variety of environmental factors.
temperature, humidity, oxidation, light and microbial exposure
Stability testing is also used to establish the shelf life of a drug product and the recommended storage conditions.
What is stress testing
Is a process that involves degradation of drug products and drug substances under conditions exceeding those used for accelerated testing and thus generates degradation products that can be studied to determine the stability of the molecule.
Long term stability studies
25ºC/60% RH or 30ºC/65% RH – 12 months (or minimum of 6) (parenteral 2-8ºC, freezer -20ºC)
Intermediate studies
30ºC ± 2C / 65% ± 5% RH – 6 months
Accelerated testing
40°C and relative humidity of 75% RH for drug substances and drug products
Rates and orders of reaction
The speed or velocity of a reaction with which a reactant or reactants undergoes a change.
Determined by the change in the concentration of the reactants or products as a function of time.
The rate, velocity or speed of a reaction is given by the expression
dc/dt = Rate = kc
Where dc is increase or decrease of concentration over a time interval dt.
Stress testing and its role in the development of pharmaceutical formulations
1.To establish degradation pathways of drug substances and drug products
2. To differentiate degradation products that are related to drug substances from those that are generated
from non-drug substances in a formulation (e.g., excipients)
3. To elucidate the structure of degradation products
4. To determine the intrinsic stability of a drug substance in formulation
5. To reveal the degradation mechanisms such as hydrolysis, oxidation, thermolysis or photolysis of the drug substance and drug product
6. To establish stability indicating nature of a developed method
7. To understand the chemical properties of drug molecules
8. To generate more stable formulations
9. To solve stability-related problems
