General Pharmacology: Comprehensive Summary Of Chapters 15

General Pharmacology Drug-Body Interactions Two major divisions: 1. Pharmacodynamics what the drug does to the body (mechanism, effects) 2. Pharmacokinetics what the body does to the drug (absorption, distribution, metabolism, excretion) ------------------------------------------------------------------------------------------------------------ Pharmacodynamics Drug permeation mechanisms Mechanism Description / Key Points Examples 1. Aqueous Diffusion Drug moves through aqueous pores/junctions; follows Ficks law (depends on gradient, thickness, area). Used by small, water-soluble, lipid-insoluble drugs. Ethanol, urea 2. Lipid Diffusion Drug crosses lipid bilayer; main absorption route. Depends on lipid solubility and ionization (only non-ionized form passes). Governed by :enderson-:asselbalch equation. Most weak acids/bases 3. Carrier-Mediated Transport Uses specific carrier proteins. =ncludes active transport (needs energy, against gradient) and facilitated diffusion (no energy, down gradient). Can be inhibited by competitors. =mportant for polar/charged drugs. Levodopa, methyldopa, Li, glucose 4. Endocytosis Engulfment of drug into vesicle entry into cell. For large or impermeant molecules; requires receptors; slow. Vit. B-intrinsic factor, iron-transferrin 5. Exocytosis Vesicular release of substances outside the cell; opposite of endocytosis. Neurotransmitters (ACh, NE) 6. Aqueous Channels (Pores) Passage via ion/protein channels; gated; only very small or ionic molecules pass. Na, K, Ca Body control targets System / Target Mechanism / Function Notes 1. =on Channels Control the flow of