Drugs are selected based on characteristics of the drug (eg, efficacy Drug Efficacy and Safety Obviously, a drug (or any medical treatment) should be used only when it will benefit a patient. Benefit takes into account both the drug's ability to produce the desired result (efficacy) and... read more , safety profile Drug Efficacy and Safety Obviously, a drug (or any medical treatment) should be used only when it will benefit a patient. Benefit takes into account both the drug's ability to produce the desired result (efficacy) and... read more , route of administration Drug Absorption Drug absorption is determined by the drug’s physicochemical properties, formulation, and route of administration. Dosage forms (eg, tablets, capsules, solutions), consisting of the drug plus... read more , route of elimination Drug Excretion The kidneys are the principal organs for excreting water-soluble substances. The biliary system contributes to excretion to the degree that drug is not reabsorbed from the gastrointestinal ... read more , dosing frequency, cost Economic Analyses in Clinical Decision Making Given limited societal and personal resources and restrictions under health insurance, cost considerations have become more relevant in clinical decision making. Limited resources should not... read more ) and of the patient (eg, age, sex, other medical problems, likelihood of pregnancy, ethnicity, other genetic determinants). Risks and benefits of the drug are also assessed; every drug poses some risk.
Response to a drug depends partly on the patient’s characteristics and behaviors (eg, consumption of foods or supplements; adherence to a dosing regimen; differences in metabolism due to age [see Pharmacokinetics in Older Adults Pharmacokinetics in Older Adults Pharmacokinetics is best defined as what the body does to the drug; it includes Absorption Distribution across body compartments Metabolism Excretion read more ], sex, race, genetic polymorphisms Pharmacogenetics Pharmacogenetics involves variations in drug response due to genetic makeup. The activity of drug-metabolizing enzymes often varies widely among healthy people, making metabolism highly variable... read more , or hepatic or renal insufficiency), coexistence of other disorders, and use of other drugs.
Drug errors Drug Errors Drug errors contribute to morbidity and mortality. They are estimated to cost the US health care system up to $177 billion (depending on definitions) annually. Drug errors may involve The wrong... read more (eg, prescribing an inappropriate drug, misreading a prescription, administering a drug incorrectly) can also affect response.