Pharmacology and Drug Mechanisms Quiz

Definitions

• Pharmacology: The science concerned with drugs, their nature, actions, mechanisms, pharmacokinetics, uses, preparations, and administration.
• Pharmacotherapeutics: The appropriate selection and application of drugs for disease prevention and treatment, focusing on therapeutic effects.
• Toxicology: The study of adverse drug effects, including side effects, overdose toxicity, and allergic reactions.
• Pharmacokinetics: The study of how drugs are absorbed, distributed, metabolized, and excreted (ADME) in the body.
• Pharmacodynamics: The study of the effects of drugs on the body and their mechanisms of action.

Agonists, Partial Agonists, and Antagonists

• Agonist: A drug that binds to receptors and mimics the action of the intended biological substance, producing a physiological response.
• Partial Agonist: Binds to receptors but produces a lesser response than a full agonist.
• Antagonist: Binds to receptors, blocking the action of agonists and preventing a physiological response.

Competitive vs Non-Competitive Antagonism

• Competitive Antagonism: Antagonist competes with agonist for the same binding site on the receptor but does not activate it, preventing the agonist effect.
• Non-Competitive Antagonism: Antagonist binds to a different site, inhibiting the receptor's activation regardless of agonist presence.

Drug Processes

• Absorption: The process by which a drug enters the bloodstream, influenced by factors like lipid solubility and ionization.
• Distribution: How the drug spreads through the body, crossing membranes via diffusion, filtration, special transport, and endocytosis.
• Metabolism: The chemical modification of a drug, often involving liver enzymes like cytochrome P-450, affecting drug efficacy and toxicity.
• Excretion: The elimination of drugs through kidneys, liver, skin, or lungs, based on molecular size and charge.

Drug Administration Routes

• Enteral: Oral, sublingual, buccal, and rectal routes.
• Parenteral: Intradermal, subcutaneous, intramuscular, intravenous, intra-arterial, intrathecal, intrapleural, intra-articular, and inhalation routes.
• Topical: Administration via skin, ear, eye, nose, vaginal, and respiratory routes.

Half-Life and Steady State

• Half-Life: Time taken for a drug's concentration to reduce by half; important for understanding dosing and scheduling.
• Steady State: Achieved when drug intake equals elimination, typically occurring after five half-lives.

Factors Affecting Drug Absorption

• Drug-related factors: Lipid/water solubility, molecular size, degree of ionization, dosage forms, and formulation.
• Body-related factors: Surface area, vascularity, pH, GI motility, presence of other substances, and health of the absorptive surface.

Protein Binding and Drug Distribution

• Protein binding affects drug distribution and therapeutic action; highly bound drugs may have altered efficacy.

Cytochrome P-450 Enzymes

• Involved in drug metabolism; inducers increase enzyme activity leading to decreased drug efficacy, while inhibitors decrease activity, increasing toxicity risks.

Active vs Inactive Metabolites

• Active Metabolites: Retain therapeutic activity.
• Inactive Metabolites: No therapeutic effect, often resulting from drug metabolism.

Adverse Drug Reactions

• Include side effects, toxicity, allergic reactions, iatrogenic diseases, and teratogenesis that can cause fetal abnormalities.
• Contraindications exist when a drug should not be prescribed due to potential harm.
• Drug interactions can alter the pharmacological effect, necessitating careful management.

Key Examples

• Inductors: Drugs like phenobarbital can increase enzyme activity in drug metabolism.
• Inhibitors: Metronidazole decreases enzyme activity, leading to increased drug toxicity.

Test your knowledge on key pharmacological concepts including agonists, antagonists, and the principles of pharmacokinetics and pharmacodynamics. This quiz covers essential definitions and applications in pharmacology and pharmacotherapeutics. Perfect for students and professionals alike.