Hepatic First pass metabolism will be encountered by which of the following routes of drug administration?

Ans. (A) Oral(Ref: KDT 8th/21)When we administer a drug orally, first it is absorbed into the portal circulation and reaches the liver. Here, some of the drugs may be metabolized (first pass metabolism or pre-systemic metabolism) and rest of the drug reaches the systemic circulation.Absorption and first pass metabolism are two important determinants of bioavailability.First pass hepatic metabolism is highest with oral route. It is also noted to some extent with rectal route.Drugs with High First pass MetabolismNitrates- NitratesHave- HydrocortisoneLarge- LignocainePre- PropranololSystemic- SalbutamolMetabolism- Morphine