Diffusion and membrane transport: Drug release from Ointment Bases

Coursework module name:
Pharmacokinetics and Drug Metabolism

please answer the following questions:

1) What is Beers Law? When is it valid?

2) Give some comments on each of the following factors which may affect release of salicylic acid from various ointment bases.
a. Characteristics of the drug
b. Characteristics of the base
c. Inclusion of various liquids in the base
d. nature of diffusion membrane used
e. Type and amount of surface active agents used, i.e., HLB system

3) if water is used as the release medium, Is it a good model to simulate the human skin? Why? What would you use to better simulate human skin.

you can ignore the style, just answer the questions.
A summary chart of the properties of ointment bases link is provided if that is useful:
bases.htm