Sex differences in salivary cortisol levels following naltrexone administration

Effects of endogenous opioid peptide blockade by naltrexone on salivary cortisol levels were examined in healthy men (n = 8) and women (n = 6). Participants received naltrexone (100 mg) during one laboratory session and a placebo pill during another session. Drug order was counterbalanced across participants. Saliva samples were collected 24 hr after each pill was administered. Among women, salivary cortisol levels significantly increased following naltrexone administration compared with a placebo pill. Naltrexone administration did not alter salivary cortisol levels in men. Results suggest sex differences in neuroendocrine sensitivity to opioid blockade, a finding that may hold significance with regard to the treatment of alcohol addiction with naltrexone.