Download Notes on Routes of Administration in Pharmacology | BMS 450 and more Study notes Pharmacology in PDF only on Docsity! 25 January Routes of Administration The route influences the rate of onset and magnitude of response. Eat something → GI tract → liver (may inactivate drugs, first pass effect – drugs which are rapidly biotransformed [molecular structure changed] are inactivated, do not want to give these orally) Parenteral route (not orally) avoids first pass effect, side effects on GI tract, binding to GI contents, biotransformation in GI tract Parenteral Topical Route Percutaneous – through the skin Hydrophilic (ionic, polar) – excluded Lipophilic molecules can diffuse through plasma membranes, hydrophilic blocked unless there is a transporter Lipophilic – penetrates by passive diffusion Steroids, DMSO, carbon tetrachloride, organic pesticides Role of surface area – greater surface area, greater effect Alveolar membrane (pulmonary endothelium) Lipophilic – passive diffusion General anesthetics, aerosols, leaded gas Particle size <2 μmm Problems: irritation, dose regulation Topical Mucosal Membranes Vagina, urethra, conjunctiva, nasal Lipophilic via passive diffusion Parenteral Intranasal Drugs with transporters at blood-brain barriers Nose is highly vascularized Counter current cooling of brain Aerosol droplet size is important Uptake from blood into cerebrospinal fluid Example: insulin Appropriate dose avoids hypoglycemia Parenteral Injection Intradermal, i.d. Liquids Oils Suspensions Slow release possible Absorption same as s.c. (subcutaneous) and i.m. (intramuscular) Subcutaneous, s.c. Liquids Oils Suspensions Solid pellets, pumps (insulin pump) Absorption generally slow and even Problems: irritation, tissue slough, severe pain (high density of sensory receptors) Intramuscular, i.m. Liquids, oils, suspensions Partial vs. completely empty syringe Parenteral injection: Other Intraarterial Diagnostic Local targeting of drug: cancer Intrathecal Spinal subarachnoid space Spinal anesthesia; CNS infections Non-lipophilic drugs Intraperitoneal (generally experimental) Large surface area, risky Emergency toxicology Enteral Route of Administration Via alimentary canal Buccal or Sublingual (cheek, under tongue) High vascularity Lipophilic drugs Avoids first pass effect Cons: distasteful or irritating drugs Rectal Lipophilic (solution, suppository) Avoids first pass effect Useful if vomiting or unconscious Cons: poor diffusion, binding, irritation
