NEU 365D Lecture Notes - Lecture 3: Botulinum Toxin, Partition Coefficient, Tubocurarine Chloride
Document Summary
Lecture 3: 9/04 - drug absorption & distribution. Drugs can vary greatly in size but are still small compared to proteins. Plays a role in the diffusion through the membrane or water channels. Might not matter for small things (ex: nitrous oxide 44 da or tubocurarine. Size can interfere at larger sizes (ex: botulinum toxin >1 mda - Pathways of drug permeation across cell membranes: passive diffusion of water-soluble drug. 1,000,000 da) drugs with low membrane/buffer partition coefficient - prefer water to oil - low p m / b (all water-soluble molecules) Through aqueous channels (aquaporins) that traverse cell membranes - Permeation rate through the channel goes down with increased molecule size: passive diffusion of lipid-soluble drugs via hydrophobic bonding with membrane lipids high p m / b compounds - passively diffuse between lipids in cell membranes (size irrelevant) Permeation rate does not vary systematically with drug molecule size.
