kinetics of drug degradation

Question 1

what is meant by shelf life?

Answer 1

the time required for the initial concentration to fall by 10% for most drugs and 5% for any potent drugs
at t90% - C = 90%Co

Question 2

what is overage?

Answer 2

it is an excess of the API that can be added to a dosage form to prevent a loss of drug potency due to degradation

Question 3

what is the Arrhenius equation?

Answer 3

used to predict the effect of T on the reaction rate (k)

k = AcE^(-Ea/RT) or lnk = lnAc - Ea/RT
T is in kelvin
A is Arrhenius constant ; frequency factor
Ea is activation factor
R is universal gas constant (8.314 J/mol K)

Question 4

what is the activation rate?

Answer 4

it is Ea

- the difference between the average energy of the reactants and minimum energy required for them to react

Question 5

what kind of conditions are medicines tested in over time?

Answer 5

• weeks to years
• 4 degrees or room temperature or 30 or 37 degrees
• ambient, 50%, 75% relative humidity

Question 6

what kind of conditions can increase degradation rates?

Answer 6

accelerated testing under high stress conditions
can be allowed to use high temp
- the Arrhenius equation is used to predict stability under storage conditions
- can get data needed in a shorter time frame