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Drug Details

NALOREX

• Drug Class Description
  Narcotic antagonists.
• Generic Name
  Naltrexone
• Presentation
  Pale yellow, film coated, capsule-shaped tablet debossed on one side with 'R11' and scored and debossed with '50' on the other side.
• Description
  Naltrexone hydrochloride 50 mg per tablet.
• Indications
  Nalorex is indicated as an adjunctive prophylactic therapy in the maintenance of detoxified, formerly opioid-dependent patients.
• Adult Dosage
  

  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.

• Child Dosage
  

  Safe use in children has not been established.

• Elderly Dosage
  

  There is no experience of use in the elderly

• Contra Indications
  

  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.

• Special Precautions
  

  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:

  -	i.v. injection of 0.2 mg Narcan
  -	if after 30 seconds no adverse reactions occur, a further i.v. injection of 0.6 mg Narcan may be administered
  -	continue to observe the patient for withdrawal effects for a further 30 minutes.

  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).

• Interactions
  

  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.

• Adverse Drug Reactions
  

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

  	an incidence of more than 10% in detoxified opioid abusers:difficulty sleeping, anxiety, nervousness, abdominal pain/cramps, nausea and/or vomiting, low energy, joint and muscle pain, and headache;
  	an incidence of less than 10%: loss of appetite, diarrhoea, constipation, increased thirst, increased energy, feeling down, irritability, dizziness, skin rash, delayed ejaculation, decreased potency, chills, chest pain, increased sweating and increased lacrimation.

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