Pharmacokinetics can be simply described as the study of 'what the body does to the drug' and includes:
• the rate and extent to which drugs are absorbed into the body and distributed to the body tissues
• the rate and pathways by which drugs are eliminated from the body by metabolism and excretion
• the relationship between time and plasma drug concentration.
Understanding these processes is extremely important for prescribers because they form the basis on which the optimal dose regimen is chosen and explain the majority of the inter-individual variation in the response to drug therapy.