first-pass effect

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 effect

the metabolism of orally administered drugs by gastrointestinal and hepatic enzymes, resulting in a significant reduction of the amount of unmetabolized drug reaching the systemic circulation.
References in periodicals archive ?
Drugs that are degradable in the gastro intestinal (GI) tract or hepatic first-pass effect that inactivates them are proper candidates for transdermal drug delivery [17].
The active ingredient, once absorbed, bypasses the liver's first-pass effect, improving therapeutic outcomes and efficacy through improves bioavailability and facilitates excellent patient compliance
At the beginning, consciousness of the patient is impaired because of a first-pass effect through the brain following its intravenous injection.
The nanoparticles were administered locally to the lung to prevent the first-pass effect in the liver.
Systemic THC levels and psychoactive effects after ingestion are highly variable because of differences in bioavailability, rate of gastrointestinal absorption, and metabolic first-pass effect whereby an orally administered drug is partially metabolized (principally in the liver) before reaching systemic distribution (6,7).
In the vaginal method, intestinal - gastric medicine absorption and hepatic first-pass effect are eliminated.
This high systemic bio availability was confirmed by the mean ratio of BPAG AUC values (81 [+ or -] 18% for sublingual dosing), which is also an estimate of the systemic bioavailability, provided that the BPAG is not formed at the administration site or by a first-pass effect, which seems to be a reasonable assumption for a direct buccal absorption.
Food and Drug Administration approved dose of 10 mg has little effect on nasal decongestion when used orally because of the drug's high first-pass effect.
Because of the hepatic first-pass effect, 1 mg of oral 17[beta]-estradiol and 25 [micro]g of transdermal estrogen yield equivalent levels of free serum estradiol.
The oral dispersible forms are also suited for active ingredients with a high first-pass effect and facilitate the rapid onset of action because of their quick dissolution
In contrast to oral administration, Dr Liu said, all of these other drug delivery routes share a common property: elimination of the first-pass effect.

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