Q1. A drug degrading by a first order process goes from 100 mg/ml to 30 mg/ml in 10 h. What is the half-life of this reaction?
Q2. A penicillin solution containing 500 units/ml has a half-life of 10 days. When will the concentration be 100 units/ml? (Assume first order degradation.)
Q3. A penicillin solution has an initial concentration of 125 mg in 5 ml. After one month in a refrigerator, the potency was found to be 100 mg in that 5 ml. What is the reaction rate constant and what is the half-life of the penicillin solution? (Assume first order degradation.)
Q4. A drug product is known to be ineffective after the drug has degraded by 30 %. The original concentration of one sample was 5.0 mg/ml. When assayed 20 months later, the concentration was found to be 4.2 mg/ml. Assuming that the decomposition was first order, what would be the shelf-life of this product? What is the half-life of this product?
Q5. In the degradation of Drug D at 35oC, the researchers found fractions of Drug D degraded at various points in time as follows.
Time (min) Fraction degraded
20 0.148
40 0.274
60 0.382
100 0.551
140 0.675
180 0.764
a. Calculate the value of the rate constant
b. What fraction would be decomposed at the end of 50 min?