Naltrexone

Combinations where caution is advised: concomitant use of naltrexone with barbiturates, benzodiazepines, anxiolytics other than benzodiazepines (e.g. meprobamate), hypnotics, sedative antidepressants (amitriptyline, doxepin, mianserin, trimipramine), sedative antihistamines H₁ and neuroleptics (droperidol) may be considered with caution.

Data from a safety and tolerability study of co-administration of naltrexone with acamprosate in non-treatment seeking, alcohol dependent individuals showed that naltrexone administration significantly increased the acamprosate plasma level.

There are no clinical data on naltrexone use in pregnancy. Data from animal studies have shown reproductive toxicity. The data are insufficient to establish clinical relevance. The potential risk for humans is unknown. Naltrexone should only be given to pregnant women when, in the judgement of the attending physician, the potential benefits outweigh the possible risk.

The use of naltrexone in pregnant alcoholic patients receiving long-term treatment with opiates or substitution treatment with opiates or in pregnant patients who are opioid-dependent, creates a risk of acute withdrawal syndrome which could have serious consequences for the mother and the fetus. Naltrexone administration must be suspended if opiate analgesics are prescribed.

There are no clinical data on naltrexone use in lactation. It is unknown whether naltrexone or 6-beta-naltexol is excreted in human breast milk. Breast feeding is not recommended during naltrexone treatment.

Naltrexone may influence psychological and physical abilities and, therefore, conduction of potentially dangerous tasks like driving vehicles or using machines should be avoided.

The following undesirable effects are classified according to system organ class and frequency: Very common (1/10), Common (1/100 to 1/10), Uncommon (1/1000 to 1/100), Rare (1/10000 to 1/1000), Very rare (1/10000), Not known (cannot be estimated from the available data).

The side effects observed with naltrexone appear to be similar in both alcoholics and patients dependent on opioids. Serious adverse reactions are unusual.

Infections and infestations

Uncommon: oral herpes, tinea pedis

Blood and lymphatic system disorders

Uncommon: lymphadenopathy

Rare: idiopathic thrombocytopenic purpura

Metabolism and nutrition disorders

Common: decrease of appetite

Psychiatric disorders

Very common: nervousness, anxiety, insomnia

Common: irritability, affective disorder

Uncommon: hallucination, confusion, despondency, depression, paranoia, disorientation, nightmares, agitation, libido disorder, abnormal dreams

Rare: suicidal ideation, attempted suicide

Nervous system disorders

Very common: headache, restlessness

Common: dizziness

Uncommon: tremor, somnolence

Eye disorders

Common: increased lacrimation

Uncommon: blurred vision, irritation and swelling of the eye, photophobia, eye pain or tiredness, colour asthenopia

Ear and labyrinth disorders

Uncommon: ear discomfort, ear pain, tinnitus, vertigo

Cardiac disorders

Common: tachycardia, heart palpitation, anomalies in the ECG

Vascular disorders

Uncommon: blood pressure changes, flushing

Respiratory, thoracic and mediastinal disorders

Common: pain in the chest

Uncommon: nasal congestion, nasal discomfort, rhinorrhoea, sneezing, oropharyngeal disorders, increased sputum, sinus disorders, dyspnoea, dysphonia, coughing, yawning

Gastrointestinal disorders

Very common: abdominal pain, nausea, emesis

Common: diarrhoea, constipation

Uncommon: flatulence, haemorrhoids, ulcus, mouth dryness

Hepatobiliary disorders

Uncommon: hepatic disorders, increased bilirubin levels, hepatitis (During treatment, increase of transaminases is possible. After discontinuing the intake of naltrexone, transaminases decrease to the original levels within some weeks.)

Skin and subcutaneous tissue disorders

Common: rash

Uncommon: seborrhea, pruritus, acne, alopecia

Musculoskeletal and connective tissue disorders

Very common: arthralgia and myalgia

Uncommon: groin pain

Very rare: rhabdomyolysis

Renal and urinary disorders

Uncommon: pollakisuria, dysuria

Reproductive system and breast disorders

Common: delayed ejaculation, erectile dysfunction, libido disorders

General disorders and administration site conditions

Very common: asthenia

Common: thirst, increased energy, chills, hyperhidrosis

Uncommon: increased appetite, weight loss, weight gain, fever, pain, sensation of cold in extremities, hot flushes