PCL201H1 Lecture 6: Lecture 6 Route of Administration and Dosing formulations
Document Summary
Topical: local application to body surface, skin, eye/nose/ear drops, sprays for mouth, throat, rectum/vagina/urethra. Intrathecal injections (space in spinal chord: body cavity injection, small volumes, low concentration for local site of drug action, low systemic concentration, specific local target. Gi tract/mucosal: oral mucosal: sublingual (blood vessels lining mucosa under tongue, rectal mucosal: suppositories, enemas, absorbed rapidly, rapid onset, systemic action, no 1st pass, low doses, e. g. Nitroglycerin: systemic or local therapy, no 1st pass, irregular absorption, problems with standard absorption routes (n/a) First pass: hepatic blood flow very close to gi tract; therefore drug enters liver before systemic circulation. Sites for metabolism include gut wall, portal bloog, and liver. Some drugs may even be excreted in bile to decrease amount of circulating drug concentration: liver: detoxification, metabolism of drugs, decrease bioavailability, highly metabolized little drug makes it to systemic circulation. Gases, vapors (anaesthetics), aerosols inhaled and absorbed through alveolar surface or bronchiole mucosa.
