PHARMACOLOGY

DRUG REACTIONS AND INTERACTIONS

Drug reactions and interactions are important concepts in pharmacology:

1. **Drug Reactions**:

- **Adverse Drug Reaction (ADR)**: An unintended and harmful reaction to a drug when used at normal doses. ADRs can range from mild (e.g., nausea, drowsiness) to severe (e.g., allergic reactions, organ damage).

- **Side Effect**: Any unintended effect of a drug that occurs at therapeutic doses. Side effects are often predictable based on the drug's known pharmacology.

- **Toxicity**: The degree to which a substance can harm a living organism. Drug toxicity can occur due to overdose or individual sensitivity.

- **Allergic Reaction**: An immune system response to a drug that is usually unpredictable and can range from mild to severe.

2. **Drug Interactions**:

- **Drug-Drug Interactions**: Occur when one drug affects the activity of another drug when both are administered together. This can lead to increased or decreased drug effects or new adverse effects.

- **Drug-Food Interactions**: Some foods can interact with drugs, affecting their absorption, metabolism, or excretion. For example, grapefruit juice can inhibit the metabolism of certain drugs, leading to increased blood levels and potential toxicity.

- **Drug-Lifestyle Interactions**: Certain lifestyle factors, such as smoking or alcohol consumption, can interact with drugs, affecting their efficacy or safety.

- **Drug-Disease Interactions**: Some drugs may have altered effects in individuals with certain diseases or conditions. For example, drugs that affect heart rate may have different effects in individuals with heart disease.

Understanding drug reactions and interactions is crucial for healthcare professionals to ensure safe and effective medication use.