Registered nurses are responsible for safe medication administration, monitoring for therapeutic and adverse effects, and patient education. Understanding basic pharmacology principles is essential: drugs work by binding to receptors to produce effects (agonists activate, antagonists block), onset/peak/duration determine when to assess for effects, and half-life determines how long the drug stays in the body. The 'Rights' of medication administration (right patient, drug, dose, route, time, documentation, reason, response) form the safety framework. Nurses must recognize adverse drug reactions, understand drug-drug and drug-food interactions, and know when to hold medications and notify the prescriber.