Hepatic First-pass
Hepatic First-pass - Related Videos
01:12
First Pass Effect
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2023
Presystemic elimination, or the first-pass effect, is the metabolism of drugs that reduces their effective concentration at the site of action. Apart from the first-pass effect, the systemic bioavailability of the drug is also reduced by other factors, including incomplete absorption or chemical degradation of drugs. Depending on the route of administration, drugs can be metabolized in the liver, intestine, lungs, and vasculature. Orally administered drugs are first absorbed through the...
10:40
Visualization and Analysis of Blood Flow and Oxygen Consumption in Hepatic Microcirculation: Application to an Acute Hepatitis Model
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Cited by 10 •
2012
An optical system was developed to visualize hepatic microcirculation with FITC-labeled erythrocytes and to measure the partial pressure of oxygen in the microvessels with laser-assisted phosphorimetry. This method can be used to investigate physiological and pathological mechanisms by analyzing microvascular structure, diameter, blood flow velocity, and oxygen tension.
09:35
Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle
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Cited by 2 •
2017
Here we describe a newly developed hepatitis B virus (HBV) reporter system to monitor the early stages of the HBV life cycle. This simplified in vitro system will aid in the screening of anti-HBV agents using a high-throughput strategy.
04:46
Targeting Liver Tumors with Oncolytic Viruses via the Hepatic Artery
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2025
The video demonstrates locoregional delivery of oncolytic viruses through hepatic arterial injection as a therapeutic approach for hepatocellular carcinoma. These viruses selectively replicate in tumor cells, inducing cell lysis and releasing tumor cell-associated antigens. This process triggers immunogenic cell death, inducing an anti-tumor response.
01:25
Single-pass Transmembrane Proteins
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2023
Integral membrane proteins are tightly associated with the cell membrane and play a crucial role in cell communication, signaling, adhesion, and transport of the molecules. Some integral membrane proteins are present only in the membrane monolayer. For example, the enzyme fatty acid amide hydrolase is present in the cytoplasmic side of the membrane monolayer. In contrast, another type of integral membrane protein, also known as a transmembrane protein, spans across the membrane. Transmembrane...
FAQs
The extent of hepatic first-pass loss depends partly on how efficiently hepatocytes transform the absorbed substance and on hepatic blood flow. Greater enzymatic transformation can leave less unchanged substance available to enter general circulation, while altered flow can change the liver’s opportunity to process it. These variables help explain why exposure may differ among medicines or clinical circumstances.
Medicines that inhibit or enhance hepatic enzymes can change the amount of a coadministered substance removed before systemic exposure. A decrease in enzyme activity may allow more unchanged drug to pass onward, whereas increased activity may reduce it. Such interactions can therefore alter oral exposure without changing the administered dose, making enzyme effects important in clinical pharmacology.
When presystemic liver metabolism substantially lowers the amount of an orally administered substance reaching general circulation, an alternative route may be considered to reduce that loss. Sublingual, transdermal, and parenteral delivery are identified as options because they can change how the substance reaches circulation. This is relevant to formulation and treatment planning.
Oral dose selection must account for the fraction lost before systemic circulation, not simply the amount swallowed. If presystemic metabolism substantially reduces bioavailability, the administered dose may produce less systemic exposure than expected from the dose alone. Considering this effect helps clinicians relate the chosen oral dose to anticipated drug exposure and supports rational comparison with alternative delivery routes.
It helps distinguish the administered oral amount from the amount available for systemic exposure. Comparing dose with resulting exposure requires attention to the presystemic contribution of hepatic metabolism, because metabolic transformation occurs before the remaining substance enters general circulation. This perspective supports interpretation of bioavailability and helps explain why oral exposure can be lower than the administered dose might suggest.
An alternative route becomes especially relevant when hepatic first-pass metabolism is expected to make oral bioavailability insufficient for the intended exposure. Sublingual, transdermal, or parenteral delivery can be considered during treatment planning to avoid relying exclusively on oral delivery. The choice is clinically meaningful because route selection changes the presystemic metabolic step that shapes systemic drug exposure.