Background: Chronic opioid use leads to physical dependence and ultimately to opioid use disorder. Abrupt discontinuation from opioids results in opioid withdrawal syndrome. Lofexidine, a central alpha-2 adrenergic agonist has been shown to mitigate symptoms of opioid withdrawal in adult patients. This work examines the safety and efficacy of lofexidine from two pooled phase 3 studies.
Methods: The data used in this analysis come from two phase 3 placebo-controlled, double-blind studies which evaluated withdrawal symptoms after abrupt discontinuation from short-acting opioids (heroin or opioid analgesics). The studies included subjects who were opioid-dependent and ≥18 years old. One of the two studies evaluated two dosages of lofexidine while the other had one lofexidine group. The pooled database consisted of 586 subjects who were randomized to lofexidine and 281 subjects to placebo. Efficacy was evaluated based on the Short Opiate Withdrawal Scale of Gossop (SOWS-Gossop). Higher SOWS-Gossop scores indicate more severe withdrawal symptoms. Adverse event information was collected during the trials and was used to evaluate safety and tolerability.
Results: The LS means for SOWS-G score over Days 1-7 was lower in both lofexidine dose groups compared with placebo (P <0.05). Patients on lofexidine stayed in treatment approximately two days longer compared to placebo. Hypotension, orthostatic hypotension, bradycardia, dizziness, somnolence, dry mouth and sedation were the most common adverse events.
Conclusions: These data suggest that lofexidine is effective at mitigating opioid withdrawal symptoms. Lofexidine was well tolerated with an adverse event profile that is measurable and manageable.