ABSTRACT
Drugs are usually administered for their local effect at the site of administration or for their systemic effects at one or more sites remote from their site of administration. Locally acting drugs are applied directly at their intended site of effect, so they exert their effect without the need for transfer to different parts of the body. However, drugs used for their systemic effects have to be absorbed from their site of administration to the systemic circulation where they are distributed to all parts of the body including their site of action. Studying the kinetics of drug absorption from the site of administration is important since the rate and extent of drug absorption have direct effect on the drug concentration-time prole in the body and, hence, the drug effect-time prole. Drug absorption is also important for locally acting drugs since the drug may be absorbed from its site of application producing undesirable systemic effects.
