ABSTRACT
Optimal drug effectiveness and safety is a combination of selecting the appropriate dose and dosing regimen, clear patient instructions, and timely follow-up evaluation. Practical drug therapy depends on continuous drug efficacy and safety monitoring relative to disease status and treatment response. Variable drug response is influenced by internal and external factors. Internal factors consist of considerations such as age, genetic determinants, disease status, physiological conditions of pregnancy, and hormonal balance. External factors include food intake, exposure to environmental chemicals, as well as drug dosage, timing, and route of administration. Hence, in order to choose the appropriate drug, the pharmacokinetic properties of the drug are examined in the context of these internal and external factors.
