Most important mechanism of drug transport across cell membrane -
Ans. is 'c' i.e., Passive diffusion o To be absorbed from the site of administration, drugs need to pass one or more cell membranes to reach their site of action.o Drugs are transported across the cell membrane by one of the following methods of transport1) Passive diffusion# It is the most important mechanism for absorption of most of the drug.# Drug diffuses in the direction of its concentration gradient across the cell membrane.# No carrier or energy is required.2) Transport by a carrier protein# It may be of two types :i) Facilitated diffusiono Transport of drug is along (in the direction of) concentration gradient and no energy is required.ii) Active transporto Transport of drug is against the concentration gradient and requires energyo It may be of two types; (a) primary and; (b) secondary (may be symport or antiport).3) Filtration# Passage of drugs through aqueous pores in the membrane or through paracellular spaces.
Fltration
Active transport
Passive diffusion
Facilitated diffusion
Pharmacokinetics