Painkillers are less effective in men than women

A new study at the State University of New York has found out why the effectiveness of some painkillers is different between women and men.

The spinal cord of female laboratory animals was found to contain almost five times more kappa-mu heterodimer - a complex of mu-opioid and kappa-opioid receptor - than the spinal cord of male animals.

Narcotic analgesics decrease pain by activating mu, delta, and kappa opiate receptors - the three main types of opioid receptor in the brain and spinal cord, which are located on nerves that transmit painful

The study further suggests that kappa-mu opioid receptor heterodimers could function as a molecular switch that shifts the action of kappa-opioid receptors and endogenous chemicals that act on them from pain promoting to pain alleviating.