first-pass effect
first-pass metabolism
presystemic metabolism

Especially the latter two enzymes contribute significantly to the first-pass effect.

The first-pass effect can also be exploited for a beneficial effect.

It also avoids the first-pass effect in the liver.

After oral administration its bioavailability is about 0.34, due to a substantial first-pass effect.

No first-pass effect was observed.

The phenomenon is known as the first-pass effect, and the Canadian researchers now are systematically testing other such drugs to determine how many may be affected by grapefruit juice.

As it becomes converted to psilocin, it undergoes a first-pass effect, whereby its concentration is greatly reduced before it reaches the systemic circulation.

Notable drugs that experience a significant first-pass effect are imipramine, morphine, propranolol, buprenorphine, diazepam, midazolam, demerol, cimetidine, and lidocaine.

If the ingredient can be identified, then the researchers wonder whether it might block the enzymes to allow nearly total absorption of drugs that are ordinarily broken down in the first-pass effect.

Alternative routes of administration like suppository, intravenous, intramuscular, inhalational aerosol, transdermal and sublingual avoid the first-pass effect because they allow drugs to be absorbed directly into the systemic circulation.

As thromboembolic complications are associated mainly with oral estrogens and attributed to the first-pass effect, they are expected to occur less frequently under parenteral therapies such as polyestradiol phosphate.

When the drug is injected, however, it avoids this first-pass effect, very rapidly crossing the blood-brain barrier because of the presence of the acetyl groups, which render it much more fat soluble than morphine itself.

All tablet dosage forms, softgels and liquid formulations primarily enter the blood stream via the gastrointestinal tract, which subjects the drug to degradation from stomach acid, bile, digestive enzymes and other first-pass effects.

The first-pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation.

There is no clear evidence of any first-pass metabolism.

Avoiding first-pass metabolism allows more of the drug to be available for treatment.

It has a high first-pass metabolism, which results in a poor bioavailability when taken orally.

However, due to extensive first-pass metabolism, only a relatively small amount enters systemic circulation.

As a result, the amount of the drug in its original form that reaches systemic circulation is reduced due to this first-pass metabolism.

Erdosteine contains two blocked sulfhydryl groups which are released following first-pass metabolism.

This is likely because of extensive first-pass metabolism by the enzyme monoamine oxidase.

Pentobarbital undergoes first-pass metabolism in the liver and possibly the intestines.

Despite complete absorption, propranolol has a variable bioavailability due to extensive first-pass metabolism.

Over 90% undergo first-pass metabolism.

The absorption of clozapine is almost complete, but the oral bioavailability is only 60 to 70% due to first-pass metabolism.

Valaciclovir is then converted to Aciclovir by esterases via hepatic first-pass metabolism.

In drug design, drug candidates may have good druglikeness but fail on first-pass metabolism, because it is biochemically selective.

Heroin is entirely converted to morphine by means of first-pass metabolism, resulting in deacetylation when ingested.

Large surface areas allow for quick drug onset, meaning greater potential for the drug to reach the central nervous system without undergoing first-pass metabolism.

Atorvastatin undergoes high intestinal clearance and first-pass metabolism, which is the main cause for the low systemic availability.

This is because the body's defenses and detoxifying mechanisms (such as first-pass metabolism in the liver with oral use) are bypassed.

Furthermore, first-pass metabolism, which is biochemically selective, can destroy the pharmacological activity of a compound despite good druglikeness.

Niazi S. Comparison of observed and predicted first-pass metabolism of nortriptyline in humans.

Because hepatic first-pass metabolism is bypassed, the effective dose is lower than oral (swallowed) selegiline.

Possible enhancement of the first-pass metabolism of phenacetin by ingestion of grape juice in Chinese subjects.

Orally administered bufotenine undergoes extensive first-pass metabolism by the enzyme monoamine oxidase.

Orally administered NMT appears to produce no psychoactive effects, likely as a result of extensive first-pass metabolism.

Sibutramine is well absorbed from the GI tract (77%), but undergoes considerable first-pass metabolism, reducing its bioavailability.

Moracizine, a phenothiazine derivative, undergoes extensive first-pass metabolism and is also extensively metabolized after it has entered the circulation.

L-Dopa metabolism is important to consider due to its extensive presystemic metabolism, rapid absorption in the proximal small intestine and short plasma half-life.

The first-pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation.