Safety and tolerability of chronic intranasal oxytocin in older men: results from a randomized controlled trial

RATIONALE: Most studies evaluating the safety and tolerability of intranasal oxytocin (OT) have not reported consistent adverse events (AEs), but they have largely focused on young men and single-dose administration. Thus, it is unclear whether these findings translate to older individuals and with longer administration periods. OBJECTIVE: Extending previous work, this study investigated the safety and tolerability of chronic intranasal OT in generally healthy older men. METHODS: Data were from a randomized, placebo (P)-controlled, double-blind clinical trial evaluating the effects of 4 weeks of self-administered intranasal OT (24 IU twice daily) in older adults with no major physical or cognitive impairments. Heart rate, blood pressure, urine osmolality, and serum metabolic biomarkers were obtained before and at the end of the intervention. AEs were collected during the first 3 weeks and 1 week after cessation of treatment. RESULTS: Of 103 participants recruited, 95 were randomized and received the intervention (OT = 49, P = 46). OT had no significant impact on cardiovascular, urine, or serum measures. The AEs reported for both treatments were generally mild and few in number, though one participant assigned to OT and two assigned to P dropped out due to AEs. Relative to P, OT did not significantly increase the likelihood of reporting AEs, nor the number or severity of AEs reported. CONCLUSION: Chronic intranasal OT appears safe and well-tolerated in generally healthy older men. These findings provide support for continued human research on potential benefits of chronic OT in older adult populations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00213-021-05862-3.