<P> After a drug is swallowed , it is absorbed by the digestive system and enters the hepatic portal system . It is carried through the portal vein into the liver before it reaches the rest of the body . The liver metabolizes many drugs , sometimes to such an extent that only a small amount of active drug emerges from the liver to the rest of the circulatory system . This first pass through the liver thus greatly reduces the bioavailability of the drug . </P>
<P> After a drug is swallowed , it is absorbed by the digestive system and enters the hepatic portal system . It is carried through the portal vein into the liver before it reaches the rest of the body . The liver metabolizes many drugs , sometimes to such an extent that only a small amount of active drug emerges from the liver to the rest of the circulatory system . This first pass through the liver thus greatly reduces the bioavailability of the drug . </P>
which route of administration is most likely to subject a drug to a first pass effect
which route of administration is most likely to subject a drug to a first pass effect
drug is swallowed
drug is swallowed