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The first-pass hepatic metabolism of a number of important therapeutic agents is inconsistent with traditional models that assume that the hepatic extraction ratio of a drug is constant in each individual (independent of the concentration of drug in the hepatic sinusoidal blood and also independent of the history of exposure to the drug). In this review, the authors examine the first-pass metabolism of five "problematic drugs" (propranolol, lidocaine, propafenone, verapamil, and nitroglycerin). Each of these compounds has unique facets to its hepatic clearance and pharmacokinetics as well as striking similarities. Selected aspects of first-pass metabolism are reviewed, and a theory that may explain some of the unusual behavior of the four lipophilic bases (propranolol, lidocaine, propafenone, and verapamil) is presented. Finally, the unusual and variable clearance of nitroglycerin is discussed. D Lalka, RK Griffith, and CL Cronenberger

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14y ago
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11y ago

First pass metabolism is when some substance (usually a drug) is altered before it can reach its site of action.

Often, drugs that are taken orally are brought by the digestive system into the hepatic portal vein into the liver, which does lots of metabolism. If the same drug could have been administered intravenously (that is, through an injection or line), it would not undergo first pass metabolism because it has bypassed the liver to get into circulation. Eventually, the drug will probably be completely metabolized either way, it's just that the oral route reaches circulation more metabolized than something injected.


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11y ago

the effect after 1st pass effect which is undergone by beta glucoronidase enzyme in small intestine .

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13y ago

If the liver biotransforms the drug extensively into an inactive form, its availability in bioactive form would be greatly reduced before it reaches its site of action

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12y ago

It means the phase of Pharmacokinetic in whic drug has to passed to liver where it is biotranformed or Metabolized and concentration of drug reduced to its orignal concentration.

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Q: What is first pass metabolism?
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What is first-pass metabolism?

First pass metabolism is when some substance (usually a drug) is altered before it can reach its site of action.Often, drugs that are taken orally are brought by the digestive system into the hepatic portal vein into the liver, which does lots of metabolism. If the same drug could have been administered intravenously (that is, through an injection or line), it would not undergo first pass metabolism because it has bypassed the liver to get into circulation. Eventually, the drug will probably be completely metabolized either way, it's just that the oral route reaches circulation more metabolized than something injected.


Will you pass a breathalyzer after not drinking for 10 hours?

You may not pass a breathalyzer after not drinking for 10 hours. Each person's metabolism is different, some could pass and some will not.


What will happen to the drug after first pass elimination when taken orallyWill the concentration of the drug decrease?

Depending on the drug, first pass can have a major influence on it's fraction reaching systemic circulation. F = fa x fg x fh Essentially the fraction reaching the systemic circulation or bioavailability (F) is influenced by fa - absorption from intestine, fg = fraction escaping metabolism in the gut, and fh = fraction escaping the first pass (metabolism) by the liver carried via the portal vein. The amount of drug reaching the systemic circulation (bioavailable) can be drastically reduced by first pass. When talking concentration, we can only measure the blood, so the amount reaching could be less.


Where does Oxidative metabolism take place?

Oxidative metabolism takes place primarily in the mitochondria of cells. Mitochondria are often referred to as the powerhouse of the cell because they generate the majority of a cell's energy through processes like the citric acid cycle and oxidative phosphorylation.


What is the effect of decreased albumin concentration on drug's absorption?

The effect of decreased albumin concentration on drug absorption is that it may cause first-pass metabolism. This may increase gastric pH levels as well.Ê


Can i chew suboxone?

There is no point of even trying to chew a Suboxone, I mean you can but it won't really effect you at all. If you place it under your tongue, the vains under your tongue with absorb the Suboxone and it will immediately storm into your bloodstream and the effects will hit you within about 30 to 60 minutes.


You smoked mariguann a two weeks ago and you been drinking a lot of water will you pass the test by tomorrow?

first learn how to spell marijuana or call it weed, foreigner. You will not pass. Rule of thumb wait a month. Factors for passing: Metabolism, diet, exercise, or if you a fat mutha F#$^%# you dont have chance.


Did you pass your drivers test on your first attempt?

Did I pass what at first attempt?


How long does it take for cocaine to pass through your system?

2 to four days depending on ur body fat amount and metabolism


Metabolism of fructose?

Fructose must pass trough the liver before being effectively used by the body.


What is the difference between root pass filling pass and copping?

Root pass is the first pass or the root penetration, filling is between the first and the second pass while capping is the covering.


The sum of all chemical processes in the body is called?

metabolism. It includes anabolism (building up molecules) and catabolism (breaking down molecules) to maintain energy, repair tissues, and eliminate waste products.