Answer 1:Pharmacokinetics involves the study of how the body absorbs, distributes, metabolizes, and excretes drugs. It is often summarized by the acronym ADME (Absorption, Distribution, Metabolism, and Excretion). Pharmacodynamics, on the other hand, focuses on the biological and physiological effects of drugs on the body and their mechanisms of action. While pharmacokinetics deals with the movement of drugs within the body, pharmacodynamics concerns the drug’s effects and the relationship between drug concentration and effect.
Question 2:What is the significance of the therapeutic index in pharmacology?
Answer 2:The therapeutic index (TI) is a crucial measure in pharmacology that compares the dose of a drug that produces a therapeutic effect to the dose that causes toxicity. It is calculated as the ratio of the toxic dose (TD50) to the effective dose (ED50). A higher therapeutic index indicates a greater margin of safety, meaning there is a wider range between the effective dose and the toxic dose. Drugs with a low therapeutic index require careful dosing and monitoring to avoid adverse effects.
Question 3:How do factors like age, weight, and genetics influence drug metabolism?
Answer 3:Several factors can significantly influence drug metabolism:
Age: Metabolism can vary with age; for example, neonates and elderly patients often metabolize drugs more slowly than adults due to immature or declining liver function.
Weight: Body weight and composition can affect the distribution and elimination of drugs. Obese patients may require different dosing due to altered drug distribution.
Genetics: Genetic variations can lead to differences in enzyme activity, affecting how individuals metabolize certain drugs. Pharmacogenetics studies these variations to optimize drug therapy for individuals based on their genetic makeup.
Question 4:What role do liver enzymes play in drug metabolism?
Answer 4:Liver enzymes, particularly those in the cytochrome P450 (CYP) family, play a crucial role in the metabolism of many drugs. These enzymes facilitate the chemical reactions that convert drugs into more water-soluble compounds, which can then be excreted from the body. The activity of these enzymes can be influenced by factors such as genetics, diet, age, and the presence of other drugs. Inhibitors or inducers of CYP enzymes can lead to significant drug interactions, altering the efficacy and toxicity of medications.