Heroin

General 8: What happens in the liver?

Heroin molecules penetrate the capillaries of the liver and the membranes of the liver cells. Liver cells contain enzymes that can convert the heroin molecules into morphine. This is a swift process: the concentration of heroin in the bloodstream is halved within 20 minutes.

Morphine is also broken down in the liver, but much more slowly. It takes 2 to 4 hours for the morphine concentration in the blood to be reduced by half. Because morphine stays in the body longer, drug tests try to detect the presence of morphine rather than heroin.

Heroin and morphine molecules, as well as morphine metabolites, are released from the liver cells into the bloodstream via the capillaries. They travel on to the rest of the body.