Naltrexone: uses, appearance and warnings

Naltrexone Hydrochloride Tablets, USP are indicated in the treatment of alcohol dependence and for the blockade of the effects of exogenously administered opioids. Naltrexone Hydrochloride Tablets, USP have not been shown to provide any therapeutic benefit except as part of an appropriate plan of management for the addictions.

Naltrexone Hydrochloride Tablets, USP 50 mg are available as a yellow film coated capsule-shaped tablet with a convex surface, debossed with a number “50” and a full bisect in between the 5 and 0 on one side and “1170” on the other side. Bottles of 30……………NDC 0406-1170-03 Bottles of 100…………..NDC 0406-1170-01 Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Dispense in a tight container. © 2026 Par Health, Inc. or one of its affiliates. Manufactured for: SpecGx LLC Webster Groves, MO 63119 USA Revised: 05/2026 Par Health™

Naltrexone hydrochloride is contraindicated in: 1. Patients receiving opioid analgesics. 2. Patients currently dependent on opioids, including those currently maintained on opiate agonists (e.g., methadone) or partial agonists (e.g., buprenorphine). 3. Patients in acute opioid withdrawal (see WARNINGS ). 4. Any individual who has failed the naloxone challenge test or who has a positive urine screen for opioids. 5. Any individual with a history of sensitivity to naltrexone hydrochloride or any other components of this product. It is not known if there is any cross-sensitivity with naloxone or the phenanthrene containing opioids.

Vulnerability to Opioid Overdose After opioid detoxification, patients are likely to have reduced tolerance to opioids. As the blockade of exogenous opioids provided by naltrexone hydrochloride wanes and eventually dissipates completely, patients who have been treated with naltrexone hydrochloride may respond to lower doses of opioids than previously used, just as they would shortly after completing detoxification. This could result in potentially life-threatening opioid intoxication (respiratory compromise or arrest, circulatory collapse, etc.) if the patient uses previously tolerated doses of opioids. Cases of opioid overdose with fatal outcomes have been reported in patients after discontinuing treatment. Patients should be alerted that they may be more sensitive to opioids, even at lower doses, after naltrexone hydrochloride treatment is discontinued. It is important that patients inform family members, and the people closest to the patient of this increased sensitivity to opioids and the risk of overdose (see PRECAUTIONS, Information for Patients ). There is also the possibility that a patient who is treated with naltrexone hydrochloride could overcome the opioid blockade effect of naltrexone hydrochloride. Although naltrexone hydrochloride is a potent antagonist, the blockade produced by naltrexone hydrochloride is surmountable. The plasma concentration of exogenous opioids attained immediately following their acute administration may be sufficient to overcome the competitive receptor blockade. This poses a potential risk to individuals who attempt, on their own, to overcome the blockade by administering large amounts of exogenous opioids. Any attempt by a patient to overcome the antagonism by taking opioids is especially dangerous and may lead to life-threatening opioid intoxication or fatal overdose. Patients should be told of the serious consequences of trying to overcome the opioid blockade (see PRECAUTIONS, Information for Patients ). Patient Access to an Opioid Overdose Reversal Agent for the Emergency Treatment of Opioid Overdose When initiating and renewing treatment with naltrexone hydrochloride, inform patients and caregivers about opioid overdose reversal agents (e.g., naloxone, nalmefene) and discuss the importance of having access to an opioid overdose reversal agent. Because of the risks for opioid overdose described above, strongly consider recommending or prescribing an opioid overdose reversal agent for the emergency treatment of an opioid overdose, both when initiating and renewing treatment with naltrexone hydrochloride. Discuss the options for obtaining an opioid overdose reversal agent (e.g., prescription, over-the-counter (some products), or as part of a community-based program). There are important differences among the opioid overdose reversal agents, such as route of administration, product strength, approved patient age range, and pharmacokinetics. Be familiar with these differences, as outlined in the approved labeling for those products, prior to recommending or prescribing such an agent. Educate patients and caregivers on how to recognize the signs and symptoms of an opioid overdose and how to use an opioid overdose reversal agent for the emergency treatment of opioid overdose. Emphasize the importance of calling 911 or getting emergency medical help in all cases of known or suspected opioid overdose, even if an opioid overdose reversal agent is administered. Precipitated Opioid Withdrawal The symptoms of spontaneous opioid withdrawal (which are associated with the discontinuation of opioid in a dependent individual) are uncomfortable, but they are not generally believed to be severe or necessitate hospitalization. However, when withdrawal is precipitated abruptly by the administration of an opioid antagonist to an opioid-dependent patient, the resulting withdrawal syndrome can be severe enough to require hospitalization. Symptoms of withdrawal have usually appeared within five minutes of ingestion of naltrexone hydrochloride and have lasted for up to 48 hours. Mental status changes including confusion, somnolence and visual hallucinations have occurred. Significant fluid losses from vomiting and diarrhea have required intravenous fluid administration. Review of postmarketing cases of precipitated opioid withdrawal in association with naltrexone treatment has identified cases with symptoms of withdrawal severe enough to require hospital admission, and in some cases, management in the intensive care unit. To prevent occurrence of precipitated withdrawal in patients dependent on opioids, or exacerbation of a pre-existing subclinical withdrawal syndrome, opioid-dependent patients, including those being treated for alcohol dependence, should be opioid-free (including tramadol) before starting naltrexone hydrochloride treatment. An opioid-free interval of a minimum of 7 to 10 days is recommended for patients previously dependent on short-acting opioids. Patients transitioning from buprenorphine or methadone may be vulnerable to precipitation of withdrawal symptoms for as long as two weeks. If a more rapid transition from agonist to antagonist therapy is deemed necessary and appropriate by the healthcare provider, monitor the patient closely in an appropriate medical setting where precipitated withdrawal can be managed. In every case, healthcare providers should always be prepared to manage withdrawal symptomatically with non-opioid medications because there is no completely reliable method for determining whether a patient has had an adequate opioid-free period. A naloxone challenge test may be helpful; however, a few case reports have indicated that patients may experience precipitated withdrawal despite having a negative urine toxicology screen or tolerating a naloxone challenge test (usually in the setting of transitioning from buprenorphine treatment). …

During two randomized, double-blind placebo-controlled 12-week trials to evaluate the efficacy of naltrexone hydrochloride as an adjunctive treatment of alcohol dependence, most patients tolerated naltrexone hydrochloride well. In these studies, a total of 93 patients received naltrexone hydrochloride at a dose of 50 mg once daily. Five of these patients discontinued naltrexone hydrochloride because of nausea. No serious adverse events were reported during these two trials. …

Studies to evaluate possible interactions between naltrexone hydrochloride and drugs other than opiates have not been performed. Consequently, caution is advised if the concomitant administration of naltrexone hydrochloride and other drugs is required. The safety and efficacy of concomitant use of naltrexone hydrochloride and disulfiram is unknown, and the concomitant use of two potentially hepatotoxic medications is not ordinarily recommended unless the probable benefits outweigh the known risks. Lethargy and somnolence have been reported following doses of naltrexone hydrochloride and thioridazine. Patients taking naltrexone hydrochloride may not benefit from opioid containing medicines, such as cough and cold preparations, antidiarrheal preparations, and opioid analgesics. …