Notes on Enteral Route Oral – Pharmacology | BMS 450, Study notes of Pharmacology

Download Notes on Enteral Route Oral – Pharmacology | BMS 450 and more Study notes Pharmacology in PDF only on Docsity! 28 January Enteral Route: Oral Convenient, economical, generally safe Trained personnel not required Compliance needed Conscious and not vomiting Disadvantages: bioavailability? Irritation, drug inactivation (acid) Biotransformation in gut, drugs with poor solubility Potential first pass effect Stomach: pH (low; high acid), fluid, short duration Limited surface area: 10 – 30% absorption Favors absorption of weak acids (ion trapping) Small intestine Microvilli – 120 square meters Most important region for drug absorption Favors absorption of weak bases (ion trapping) pH 5 – 8 Large intestine (colon) No villi, paste (low diffusion) Few transporters Low drug absorption Considerations Too fast – poor absorption with slow dissolving drugs Too slowly – acid may degrade, biotransformation Absorption of Oral Drugs Passive diffusion Lipophilic drugs; downhill transport Not concentration dependent Concentration inside with equal concentration outside Reach equilibrium across membrane Uptake proportional to concentration Uptake nonsaturable Carrier-mediated; facilitated transport Ionic/polar Concentration dependent, will saturate Transporters Downhill transport Equilibrium will occur Active transport; carrier-mediated Polar or ionic drugs; uphill transport Use ATP, against concentration gradient Saturates with drug concentration Energy-dependent; can be inhibited Cyanide, dinitrophenol Amount inside can exceed amount outside Pinocytosis ATP dependent