Naltrexone dampens ethanol-induced cardiovascular and hypothalamic- pituitary-adrenal axis activation.

Alcohol ingestion activates the autonomic nervous system and the hypothalamic-pituitary-adrenal axis. This study examined naltrexone effects on alcohol-induced increases in physiological responses and their association with alcohol liking. Using a within-subjects design, heavy drinking men (N = 19) were maintained on each of three naltrexone doses (0, 50, and 100 mg, p.o.) over an 8-day inpatient stay. Within each naltrexone dose, subjects had three alcohol challenge sessions (none, moderate, high) in random order. Autonomic, subjective and endocrine measurements were collected regularly prior to and following alcohol administration. High-dose alcohol ingestion increased heart rate, diastolic blood pressure, skin temperature, ACTH, cortisol and liking of drink effects; responses following the moderate alcohol dose were less consistent. Naltrexone significantly dampened alcohol-induced increases in heart rate, diastolic blood pressure, hormone levels and subjective liking of drink effects. This dampening of cardiovascular and hormonal responses may contribute to the therapeutic effectiveness of naltrexone for reducing alcohol liking and decreasing relapse in alcohol-dependent persons.