Thiopentone is used for induction of anaesthesia. It shows marked redistribution which is a characteristic of:
* Highly lipid- soluble drugs get initially distributed to organs with high blood flow,i.e. brain, hea, kidney, etc. * Later, less vascular but more bulky tissues (muscle, fat) take up the drug. Plasma concentration falls and the drug is withdrawn from the highly perfused sites. * If the site of action of the drug was in one of the highly perfused organs, this redistribution results in termination of drug action. Anaesthetic action of thiopentone sod. injected IV is terminated in few minutes due to redistribution. * Greater the lipid solubility of the drug, faster is its redistribution
Highly lipid soluble drugs
Highly water soluble drugs
Weak electrolytes
Highly plasma protein bound drugs
Pharmacokinetics