Heroin is a semisynthetic drug, developed from morphine, a natural opioid found in poppies. When heroin is injected, the body very quickly breaks it down into morphine, and it is actually the morphine that acts in the brain. It binds to opioid receptors, resulting in the flood of dopamine that triggers euphoria as well as slowing down central nervous system activity, reducing heart rate and breathing. The half-life for heroin in the body is just a few minutes, which means that half of the drug has already broken down into other substances within a few minutes of taking it.
Although heroin in its original form doesn’t actually last that long in the body, it is more potent than morphine because it is able to get into the brain more quickly than morphine can. Once in the brain it breaks down rapidly, but this quick action is one reason that heroin is so addictive. The effects of heroin can be felt within a few seconds of injecting it and within just a couple of minutes of snorting it. The quick break down to morphine makes the high quick, intense, and short-lived.
Morphine is not the only metabolite, or breakdown product of heroin. There are several other products that last longer in the body than heroin or morphine. These, including a compound known as 6-acetylmorphine, can be detected much later than the original drug. This particular metabolite has a half-life closer to 30 minutes. Drug tests for heroin rely on the persistence of metabolites, particularly in urine. The tests detect these in order to determine someone has used the drug, and this can be done up to three days after the last use.
