Possible Interaction: Melatonin and Propranolol

“These data show that only the specifically beta-blocking (S)-enantiomers of propranolol and atenolol decrease the nocturnal production of melatonin whereas the non-beta-blocking (R)-enantiomers have no effect.”

“ Propranolol caused a dose-dependent decrease in melatonin levels in both the dark and the light.”

“The hypothesis is based mainly on the following facts: (1) melatonin is well known to exert an inhibitory effect on gonadotropin secretion; (2) … dramatically increases the inhibitory effect of exogenous melatonin on gonadotropin-releasing hormone-induced gonadotropin secretion in female rats; (4) the administration of propranolol in … melatonin and, ….”

“Nighttime elevations of melatonin in cerebrospinal fluid were also suppressed by propranolol and light.”

“ Propranolol , owing to its lipophilicity, has the ability to cross the bloodbrain barrier and interfere with the melatonin secretion potentially leading to sleep disturbances.2 An additional potential mechanism could be increased wakefulness due to lower blood sugar levels.”

“ Propranolol did not cause any change in E2 secretion, and when given with Me , it only partially blocked but could not entirely prevent E2 output.”

“ Melatonin stimulated progesterone secretion and, like adrenaline, this stimulation was prevented by propranolol.”

“ Melatonin and prolactin levels in serum decreased noticeably with propranolol treatment.”

“Patients with alcoholism, migraine, postoperative pinealoma, panhypopituitarism, hereditary dystonia and schizophrenics on propranolol exhibited a decreased amplitude of their diurnal rhythm of melatonin.”

“Isoproterenol administration (2 microg/g body wt) at … +/- 40 pM to 1,298 +/- 160 pM, whereas propranolol (… melatonin secretion from 1,270 +/- 128 pM to 395 +/- 66 pM. The rise of pineal and plasma … after dark onset, respectively, preceding the onset in dams by 3 and 4 h, respectively.”