Paul Walker has topped the Google UK Zeitgeist chart of the most searched for people on the internet in 2013. The late Fast & Furious star, who died in a car crash on 30 November, was laid to rest during a funeral on Sunday.
Understanding First Pass Metabolism. The drug is absorbed from the GI tract and passes via the portal vein into the liver where some drugs are metabolised. Sometimes the result of first pass metabolism means that only a proportion of the drug reaches the circulation. First pass metabolism can occur in the gut and the liver. For example, first pass metabolism occurs in the gut for benzylpenicillin and insulin and in the liver for propranolol, lignocane, chloromethiasole and GTN.
If the drug is metabolized in the liver or excreted in the bile, some of the active drug will be destroyed before it can reach the general blood circulation and be distributed to its site of action. If the metabolic capacity of the liver for a given drug is great, bioavailability will be substantially decreased. This is called the first pass effect. The decrease in availability of the drug is a function of the anatomical site from which absorption occurs, as well as other physiological and pathological conditions.