Drug disposition, bioavailability and efficacy

In this article, we will look at the concepts of drug disposition, bioavailability and efficacy. Drug distribution can be defined as getting a drug into its appropriate position in the body at an appropriate concentration. This is represented by pharmacokinetic properties such as absorption, distribution, metabolism and excretion. Here we will concentrate on the movement of drug molecules at a tissue and cellular level to discover how drug molecules cross membranes and are distributed into the relevant body compartments to have their effect. We will also look at the concept of bioavailability, which is the fraction of an administered dose of unchanged drug that reaches the systemic circulation, and efficacy, which is maximum response achievable to elicit a therapeutic response.