Question

1.An antihypertensive drug, formulated as a 10 mg tablet, was stored at elevated temperatures and the content of the drug analysed. The first order kinetic rate constants for the degradation reaction at each temperature are given below.

 

Temperature (°C)

35 - 45 - 55 - 70

Rate constant (weeks–1)

0.0025 -0.0056 -0.0123 -0.0351

1. A three-year shelflife,based on a 90% lower limit for the active ingredient is required. What storage temperature would you recommend, to ensure the necessary shelf-life? (3 marks)

2. In addition to the tablet, it is intended to produce an aqueous suspension of the drug. Give the major factors, with regard to stability, that you would consider in designing this product.