Biomedical Engineering: Bridging Medicine and Technology 1st Edition by Veronique Tran,Mark Saltzman

Exercise 3

Drugs are often administered in capsules. Some capsules act as containers, which hold many smaller particles that contain the active agent. Administra- tion of the drug is improved by the capsule; when the capsule breaks down in the intestine and the particles are freed from the container, the large surface area of the drug particles allows rapid dissolution of the drug.
a. Assume that a capsule is approximately 1 cm long and 3 mm in diameter. Calculate the surface-to-volume ratio of the capsule.
b. Assume that the capsule is filled with particles that are 0.4 mm in diameter. How many of these particles will fit into one capsule?
c. What is the total surface area of the particles within the capsule?