Search The Medical Knowledge Base
Drug Details
Opizone 50mg film-coated Tablets
- Presentation
Film-coated tablet. Capsule shaped, beige film-coated tablets with a break-score on each side. The tablet can be divided into equal halves. - Description
Each film-coated tablet contains 50 mg naltrexone hydrochloride. - Indications
For use as an additional therapy within a comprehensive treatment program including psychological guidance for detoxified patients who have been opioid-dependent.
- Adult Dosage
Opizone treatment should be initiated and supervised by suitable qualified physicians.
Use in adults
The recommended initial dose of naltrexone hydrochloride is 25 mg (half a tablet) followed by 50 mg per day (one tablet).
The dosage-regimen can be modified in order to improve compliance to a three-times-a-week dosing schedule as follows: administration of 2 tablets (= 100 mg naltrexone hydrochloride) on Monday and on Wednesday and 3 tablets (= 150 mg naltrexone hydrochloride) on Friday.
A missed dose can be managed by providing 1 tablet per day till the next regular dosage-administration.
Opizone administered to opioid-dependent persons can cause life-threatening withdrawal symptoms. Patients suspected of using or being addicted to opioids must undergo a naloxone provocation test, unless it can be verified that the patient has not taken any opioids for 7-10 days (urine test) prior to the initiation of treatment with naltrexone.
As Opizone is an adjunctive therapy and the full recovery process in opioid-dependent patients is individually variable, no standard duration of treatment can be stated; an initial period of three months should be considered. However, prolonged administration may be necessary.
- Child Dosage
Use in children and adolescents
Opizone is not recommended for use in children and adolescents below 18 due to a lack of data on safety and efficacy.
- Elderly Dosage
Use in elderly
The experience in elderly patients is limited.
- Contra Indications
- Hypersensitivity to naltrexone hydrochloride or to any of the excipients
- Acute hepatitis
- Severe hepatic impairment
- Severe renal impairment
- Opioid addicted patients with a current abuse of opioids since an acute withdrawal syndrome may ensue.
- Positive screening result for opioids or after failure of the naloxone provocation test.
- Special Precautions
In accordance to national guidance the therapy should be initiated and supervised by a physician experienced in treatment of opioid-addicted patients.
High dose opioid intake, concomitant with Opizone treatment, can lead to life-threatening opioid poisoning from respiratory and circulatory impairment.
Should Opizone be used in opioid-dependent patients a withdrawal syndrome may occur rapidly: the first symptoms can occur within 5 minutes, the last after 48 hours. The treatment of withdrawal symptoms is symptomatic.
Patients must be warned against the concomitant use of opioids (e.g. opioids in cough medication, opioids in symptomatic medication for the treatment of common colds, or opioids contained in anti diarrhoeal agents, etc.) during Opizone treatment.
During treatment with Opizone, painful conditions should be treated with non-opioid analgesia only.
If a patient needs opioid treatment, e.g. opioid analgesia or anaesthesia in emergency situations, the opioid dose needed to achieve the desired therapeutic effect may be larger than normal. In these cases, respiratory depression and circulatory effects will be more profound and longer lasting. Symptoms related to release of histamine (diaphoresis, itching and other skin and mucocutaneous manifestations) can also be manifested more easily. The patient requires specific attention and care in these situations.
Patients suspected of using or being addicted to opioids must undergo a naloxone provocation test, unless it can be verified that the patient has not taken any opioids for 7-10 days (urine test) prior to the initiation of treatment with naltrexone.
A withdrawal syndrome precipitated by naloxone will be of shorter duration than withdrawal precipitated by naltrexone.
The recommended procedure is as follows:
Intravenous provocation
- Intravenous injection of 0.2 mg naloxone
- If after 30 seconds no adverse reactions occur, a further i.v. injection of 0.6 mg naloxone may be administered.
The patient should be observed continuously for 30 minutes for any detectable sign of withdrawal symptoms.
If any symptoms of withdrawal occur Opizone-therapy must not be undertaken. If the test-result is negative the treatment can be initiated. If any doubt exists that the patient is opioid-free, the challenge may be repeated with the dosage of 1.6 mg. If no reaction occurs after this, 25 mg of naltrexone hydrochloride can be administered to the patient.
A naloxone hydrochloride provocation test should not be made in patients with clinically prominent withdrawal symptoms nor in any case of a positive urine test for opioids.
Patients should be warned that large doses of opioids to overcome the blockade may after the cessation of the Opizone result in an acute opioid overdose, with possible fatal outcome.
Patients might be more sensitive to opioid containing medicines after treatment with Opizone.
Naltrexone hydrochloride is extensively metabolised by the liver and excreted predominantly in the urine. Therefore, caution should be observed in administering the medicinal product to patients with impaired hepatic or renal function. Liver function tests should be carried out both before and during treatment.
Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
- Interactions
Presently, clinical experience and experimental data on the effect of naltrexone on the pharmacokinetics of other substances are limited. Concomitant treatment with naltrexone and other medicinal products should be conducted with caution and should be followed carefully.
No interaction studies have been performed.
In vitro studies have shown that neither naltrexone nor its main metabolite 6-ß-naltrexol is metabolised via human CYP450 enzymes. Therefore it is unlikely that the pharmacokinetics of naltrexone is affected by cytochrome P450 enzyme inhibiting drugs.
One case of lethargy and somnolence has been reported after concomitant use of naltrexone and thioridazine.
Until now no interaction between cocaine and naltrexone hydrochloride has been described.
There are no known interactions between naltrexone and alcohol.
- Adverse Drug Reactions
The following undesirable effects are ranked according to system organ class and to their frequency:
Very common (
1/10)Common (
1/100 to < 1/10)Uncommon (
1/1.000 to < 1/100)Rare (
1/10.000 to < 1/1.000)Very rare (< 1/10.000)
MedDRA system organ class Symptom Very common Nervous system disorder Headache Sleep disorders Restlessness Nervousness Gastrointestinal disorder Abdominal pain Abdominal cramps Nausea Inclination to vomit Musculoskeletal and connective tissue disorders Joint and muscle pain General disorder and administration site conditions Feebleness Common Nervous system disorders Thirst Dizziness Shivering Increased transpiration Vertigo Eye disorders Increased lacrimation Respiratory, thoracic and mediastinal disorder Pain in the chest Gastrointestinal disorders Diarrhoea Constipation Renal and urinary disorders Urine retention Skin and subcutaneous tissue disorder Rash General disorders and administration site conditions Lack of appetite Reproductive system and breast disorders Delayed ejaculation Decreased potency Psychiatric disorders Anxiety Increased energy Despondency Irritability Mood swings Rare Nervous system disorders Speech disorder Gastrointestinal disorders Hepatic disorders Psychiatric disorders Depression Suicidal ideation Attempted suicide Very rare Blood and lymphatic system disorders Idiopathic thrombocytopenic purpurea Nervous system disorders Tremor Skin and subcutaneous tissue disorders Exanthema Psychiatric disorders Agitation Euphoria Hallucination