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
Farlex Partner Medical Dictionary © Farlex 2012

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.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

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
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
This averts the "first pass effect," in which the liver metabolizes medication, preventing much of it from getting into the bloodstream.
Buccal absorption is similar to sublingual in that the goal is to maximise oral absorption, bypassing the first pass effect of metabolism (metabolized by the liver) that occurs during digestion.
Dydrogestrone is an oral preparation used in Northwest Women's Hospital, and it has a first pass effect. Dydrogesterone has a good safety and tolerability profile.
Although the dydrogesterone tablet had first pass effect, and there was no significant difference in efficacy between two groups (p greater than 0.05), the success rates of fetal protection in the dydrogestrone group was slightly higher.
Total recoveries of Pd-la within 24 h were low (0.097% in bile, 0.120% in urine and 0.009% in feces), which might be resulted from liver first pass effect.
The other was from liver first pass effect, in other words, Pd-la absorbed in blood would be metabolized by liver drug enzyme.
Low recoveries of Pd-la in bile, urine and feces indicated that few intact form of Pd-la was excreted by bile and kidney, which might be resulted from liver first pass effect. Thus, monitoring of the liver function may become necessary and dose adjustment is needed in patients whose liver metabolic function is impaired.
Aegis' Intravail absorption agents have numerous competitive advantages, including rapid drug absorption and onset of action, controlled transient permeation of the nasal mucosal barrier with no or minimal irritation, avoidance of gastric hydrolysis in the stomach and "first pass effect" elimination by the liver that can accompany oral administration, greater patient convenience and compliance, elimination of needlestick injuries and associated transmission of bloodborne pathogens, compatibility with current nasal delivery devices, ease of formulation and compatibility with routine homogeneous formulation and dispensing manufacturing processes for ease of scale-up and production
For example, if the route is ingestion, much of the chlorpyrifos may be metabolized to TCPy in the first pass effect before chlorpyrifos reaches the maternal systemic blood supply and hence the placenta (Figure 2).
"Further study is needed to help determine if transdermal administration of estrogen therapy has the same effect on biliary tract outcomes, since the first pass effect would be lessened," they noted.
The pills can be taken within 12 hours, and are easier than vaginal administration, avoid the first pass effect through the liver as in oral administration, and offer more privacy during the process.
This "first pass effect" means that several doses of the drug must be administered before a therapeutic level is achieved in the bloodstream.

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