What Is First-Pass Metabolism?

Drugs.com defines first-pass metabolism as the intestinal and hepatic degradation or alteration of a drug or substance taken by mouth after absorption that removes some of the active substance from the blood before the substance enters the general circulation. The National Institute of Alcohol Abuse and Addiction explains that first-pass metabolism has some significance in learning how the body can dispose of alcohol and what factors aid in this disposal.

In an Alcohol Alert on About.com, NIAAA director Dr. Enoch Gordis states that the study of metabolism has both practical and broader scientific implications because information on how the body metabolizes alcohol may help predict blood alcohol concentration after drinking when factoring in elements such as food consumption and gender. Gordis further explains that data from two large-scale NIAAA-supported genetics studies suggest that alcohol dehydrogenase genes may be associated with differential resistance and vulnerability to alcohol, which helps in understanding why some people develop alcoholism and others do not.

Gordis cites academic research from various sources including The New England Journal of Medicine that looks at the connection between gender and first-pass metabolism to support his point that studying alcohol metabolism may help bring understanding in how this process influences the metabolism of food, hormones and medications.