Final answer:
A drug's effect on a person is influenced by factors including (a) patient's age, (b) weight, (c) drug dosage, (d) drug metabolism, and (e) gender, as well as genetic characteristics and potential interactions with food or other drugs.
Step-by-step explanation:
The effect of a drug on a person can be influenced by a variety of factors, including the patient's age, patient's weight, drug dosage, drug metabolism, and the patient's gender. For instance, the metabolism and excretion of drugs, part of the ADME processes, can vary considerably among individuals.
Factors such as genetic polymorphism, co-existing diseases, and drug-drug interactions (DDI) can lead to significant variability in how a drug acts within the body. Additionally, the necessity for therapeutic drug monitoring (TDM) is reinforced to ensure optimal therapeutic drug concentrations and to limit toxicity.
It is also important to consider the route of drug administration, with intravenous administration leading to a faster peak in drug plasma concentrations, in contrast to oral or intramuscular routes. Furthermore, diseases affecting liver or kidney function may impede drug metabolism or clearance, raising the risk of drug toxicity.
Lastly, the drug's half-life and whether it is dose-dependent (effectiveness based on large doses for short durations) or time-dependent (effectiveness based on maintaining optimum levels over longer periods) also influence drug efficacy and safety.