NALOREX 50mg Film-Coated Tablets

Naltrexone hydrochloride 50 mg per tablet.

Pale yellow, film coated, capsule-shaped tablet debossed on one side with 'R11' and scored and debossed with '50' on the other side.

Nalorex is indicated as an adjunctive prophylactic therapy in the maintenance of detoxified, formerly opioid-dependent patients.

Route of administration - oral.

Nalorex treatment should be initiated in a drug addiction centre and supervised by suitably qualified physicians.

The initial dose of Nalorex should be 25 mg (half a tablet) followed by 50 mg (one tablet) daily.

A three-times-a-week dosing schedule may be considered if it is likely to result in better compliance e.g. 100 mg on Monday, 100 mg on Wednesday and 150 mg on Friday.

Treatment with Nalorex should be considered only in patients who have remained opioid-free for a minimum of 7-10 days.

Narcan® (Naloxone hydrochloride) challenge is recommended to minimise the chance of a prolonged withdrawal syndrome precipitated by Nalorex (see also Warnings).

As Nalorex is an adjunctive therapy and full recovery from opioid dependence is variable, no standard duration of treatment can be recommended; an initial period of three months should be considered. However, prolonged administration may be necessary.

Use in Children

Safe use in children has not been established.

Use in Elderly

There is no experience of use in the elderly.

Nalorex should not be given to patients with acute hepatitis or liver failure.

Nalorex should not be given to patients currently dependent on opioids since an acute withdrawal syndrome may ensue.

Nalorex should not be used in conjunction with an opioid-containing medication.

Nalorex should not be given to patients who are hypersensitive to it.

It is not uncommon for opioid abusing individuals to have impaired liver function.

Liver function test abnormalities have been reported in obese and elderly patients taking naltrexone who have no history of drug abuse. Liver function tests should be carried out both before and during treatment.

Since NALOREX is extensively metabolised by the liver and excreted predominantly in the urine, caution should be observed in administering the drug to patients with impaired hepatic or renal function. Liver function tests should be carried out both before and during treatment.

A withdrawal syndrome may be precipitated by NALOREX in opioid dependent patients; signs and symptoms may develop within 5 minutes and last up to 48 hours. Treatment should be symptomatic and may include opioid administration.

Narcan (Naloxone Hydrochloride) challenge is recommended to screen for presence of opioid use; a withdrawal syndrome precipitated by Narcan will be of shorter duration than one precipitated by Nalorex.

The recommended procedure is as follows:

If doubt exists that the patient is opioid-free, the challenge may be repeated with a Narcan dose of 1.6 mg.

If there is no evidence of a reaction, Nalorex administration may be initiated with 25 mg by mouth (half a tablet).

Concomitant administration of Nalorex with an opioid-containing medication should be avoided. Patients should be warned that attempts to overcome the blockade may result in acute opioid intoxication which may be life threatening. In an emergency requiring opioid analgesia an increased dose of opioid may be required to control pain. The patient should be closely monitored for evidence of respiratory depression or other adverse symptoms and signs.

Animal studies do not suggest a teratogenic effect. Because of absence of documented clinical experience Nalorex should only be given to pregnant or breast-feeding women when, in the judgement of the attending physician, the potential benefits outweigh the possible risks.

Nalorex may impair the mental and/or physical abilities required for performance of potentially hazardous tasks such as driving a car or operating machinery.

The following adverse reactions have been reported before and during naltrexone medication:

Occasional liver function abnormalities have also been reported. One case of reversible idiopathic thrombocytopenic purpura has occurred in a patient taking Nalorex.

There is no clinical experience with NALOREX overdose in patients. There was no evidence of toxicity in volunteers receiving 800 mg/day for seven days, however, in case of overdose, patients should be monitored and treated symptomatically in a closely supervised environment.

Naltrexone is a specific, high affinity, long acting competitive antagonist at opioid receptors. It has negligible opioid agonist activity. Tolerance does not develop with prolonged use.

Naltrexone is rapidly absorbed after oral administration. It is metabolised by the liver and excreted primarily in the urine, less than 5% is excreted in the faeces. Naltrexone has an elimination half-life of four hours. The major metabolite 6-beta-naltrexol has an elimination half-life of 12.9 hours.

Nalorex is well established in medical use. Preclinical data is broadly consistent with clinical experience.

Not applicable

36 months

Do not store above 25°C. .

White opaque PVC/PE/Aclar blister or white opaque PVC/Aclar/PVC blister with aluminium foil in packs of 28 tablets.

Not applicable.

PL 11184/0104

31 July 1992 / 10 October 2005

August 2009