first-pass metabolism


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first-pass metabolism

the intestinal and hepatic degradation or alteration of a drug or substance taken by mouth, after absorption, removing some of the active substance from the blood before it enters the general circulation.
Synonym(s): first-pass effect

first-pass me·tab·o·lism

, first-pass effect (fĭrst-pas mĕ-tab'ŏ-lizm, e-fekt')
The intestinal and hepatic degradation or alteration of a drug or substance taken by mouth, after absorption, removing some of the active substance from the blood before it enters the general circulation.

first-pass metabolism

The metabolism of a substance that occurs immediately as it enters the body, and before it can exert any effect, or before it can be measured at its target organ.
See also: metabolism
References in periodicals archive ?
Site and quantitative importance of alcohol first-pass metabolism.
The main impact of liver disease is on phase I enzymes, which will affect both clearance and first-pass metabolism.
Although some investigators have reported no significant pharmacokinetic interactions when these cannabinoids were coadministered to humans in vivo (15), others have suggested that CBD inhibits cytochrome P450 (CYP) 2C (16) and 3A (17) enzymes, reducing first-pass metabolism to 11-OH-THC.
In general, probably only a small fraction (perhaps 10 percent) of ingested alcohol is eliminated from the body by first-pass metabolism after consumption of low doses of alcohol.
Avoiding first-pass metabolism in the liver prevents the production of metabolites that can alter the drug's safety and side effect profile, said Dr.
Consideration should also be given to the possibility that some of the sublingual formulation may have been swallowed, resulting in first-pass metabolism of DHT to AG.
But the complex structure of therapeutic proteins on which their efficacy depends require special formulation and delivery strategies to avoid first-pass metabolism, extend therapeutic half-life and prevent these expensive drugs from drawing the attention of the immune system - all issues that diminish or eliminate their therapeutic value and potential.
Considered by many to be a niche delivery technology, transdermal drug patches offer the advantages of ease of use, painlessness, disposability, control of drug delivery and avoidance of first-pass metabolism by the liver.
In the enriched patient population, this corresponded with evidence of earlier efficacy for the LS in comparison with a 50-mg tablet; the lower dose size for the former was consistent with oral mucosal drug absorption, and evasion of first-pass metabolism.
Transdermal drug delivery patches offer the advantages of ease of use, painlessness, disposability, control of drug delivery and avoidance of first-pass metabolism by the liver.
The first-pass metabolism of a parenteral enhances its bioavailability.
Complicating matters, dose-absorbing food, first-pass metabolism, and safety-driven dose-reduction and stoppage protocols further reduce lung dose and interrupt maintenance therapy.