Suicidal ideation, suicidal behaviour and depression
Suicidal ideation and behaviour have been reported in patients treated with antiepileptic agents for various indications. A meta-analysis of randomised placebo controlled trials of antiepileptic drugs has also shown a small increased risk of suicidal ideation and behaviour. The mechanism of action regarding this risk is not known and the available data do not exclude the possibility of an increased risk for clonazepam.
Therefore patients should be monitored for signs of suicidal ideation and behaviours and appropriate treatment should be considered. Patients (and caregivers of patients) should seek medical advice if signs of suicidal ideation or behaviour emerge. Patients with a history of depression and/or suicide attempts should be kept under close supervision.
CNS
Clonazepam may be used only with particular caution in patients with spinal or cerebellar ataxia.
Concomitant use with alcohol/CNS depressants
The concomitant use of clonazepam with alcoholic beverages and/or CNS depressants should be avoided. Such concomitant use has the potential to increase the clinical effects of clonazepam, including severe sedation, clinically relevant respiratory and/or cardiovascular depression (see section 4.5).
Amnesia
Anterograde amnesia may occur with the use of benzodiazepines at therapeutic doses and the risk increases with higher doses.
Myasthenia gravis
Particular caution should be exercised when administering clonazepam to patients with myasthenia gravis due to the additional risk for muscle weakness and respiratory depression.
Psychiatric and "paradoxical" reactions
During treatment with benzodiazepines, paradoxical reactions such as restlessness, agitation, irritability, aggression, anxiety, delusions, anger, nightmares, hallucinations, psychosis, inappropriate behavior, and other behavioral disorders have been reported (see section 4.8). Paradoxical reactions may be a class effect of benzoidazepines. If this occurs during treatment with Clonazepam, gradual discontinuation of treatment should be considered (see Discontinuation of treatment or dose reduction). Paradoxical reactions are more common in children and the elderly.
Paediatric population
Due to the presence of ethanol, benzyl alcohol and propylene glycol in the formulation, this medicinal product is not indicated for use in infants and in children under 12 years (see section 4.3).
Respiratory disorders
The dosage of clonazepam must be carefully adjusted to individual requirements in patients with pre-existing disease of the respiratory system (e.g. chronic obstructive pulmonary disease). Effects on the respiratory system may be aggravated by pre-existing airways obstruction or brain damage or if other medications which depress respiration have been given. As a rule, this effect can be avoided by careful adjustment of the dose to individual requirements.
Responsiveness
Like all drugs of this type, Clonazepam may, depending on dosage, method of administration and individual susceptibility, modify the patient's reactions (e.g. driving ability, behaviour in traffic) (see section 4.7).
As a general rule, epileptic patients are not allowed to drive. Even when the condition is adequately controlled on clonazepam, it should be remembered that any increase in dosage or alteration in timing of administration may modify the patient's reactions, depending on individual susceptibility. See also section 4.7.
Concomitant anti-epileptic treatment
The dosage of clonazepam must be carefully adjusted to individual requirements in patients undergoing treatment with other centrally acting medications or anticonvulsant (antiepileptic) agents (see section 4.5).
Interruption of treatment or dose reduction
Administration of anticonvulsants, including clonazepam, must not be abruptly interrupted because of the risk of precipitating status epilepticus. If the attending physician decides for the need for dose reduction or discontinuation, this has to be done gradually. In such cases a combination with other antiepileptics is recommended.
Intravenous administration
A vein of acceptable diameter should be selected for intravenous administration. The injection must be administered very slowly, under constant monitoring of EEG, respiration and blood pressure. Rapid injection or insufficient diameter of the vein are associated with the risk of thrombophlebitis that can lead to thrombosis. Respiratory depression may occur, particularly following intravenous administration of clonazepam.
In adults and adolescents, the injection rate should not exceed 0.25-0.5 mg (0.5-1 ml of prepared solution) per minute (see section 4.2). Adverse effects involving the nervous and muscular system including fatigue, are quite frequent and usually transient. They generally disappear spontaneously in the course of treatment or with dose reduction. These effects can be partially prevented by increasing the dose slowly at the start of treatment (see section 4.8).
Porphyria
Clonazepam may trigger attacks of porphyria. Therefore in patients with porphyria, clonazepam should be used with care.
History of drug abuse and dependence
Use of benzodiazepines may lead to the development of physical and psychological dependence (see section 4.8). In particular long-term or high-dose treatment may lead to reversible disorders such as dysarthria, reduced coordination of movements and gait disorder (ataxia), nystagmus and vision disorders (diplopia). Anterograde amnesia may occur using benzodiazepines at therapeutic dosages, the risk increases at higher dosages. Amnestic effects may be associated with inappropriate behaviour. With certain forms of epilepsy, an increase in the frequency of seizures (see section 4.8) during long-term treatment is possible.
The risk of dependence and/or abuse increases with dose and duration of treatment. It is also higher in patients with a prior history of alcohol and/or drug abuse.
Once physical dependence has developed, abrupt termination of treatment will be accompanied by withdrawal symptoms. During long-term treatment, withdrawal symptoms may develop after a lengthy period of use, especially with high doses or if the daily dose is reduced rapidly or abruptly discontinued. The symptoms include tremor, sweating, agitation, sleep disturbances and anxiety, headaches, muscle pain, extreme anxiety, tension, restlessness, confusion, irritability and epileptic seizures which may be associated with the underlying disease.
In severe cases the following symptoms may occur: derealisation, depersonalisation, hyperacusis, numbness and tingling of the extremities, hypersensitivity to light, noise and physical contact or hallucinations. Since the risk of withdrawal symptoms is greater after abrupt discontinuation of treatment, abrupt withdrawal of the drug should therefore be avoided and treatment - even if only of short duration - should be terminated by gradually reducing the daily dose. The risk of withdrawal symptoms is increased when benzodiazepines are administered together with day-time sedatives (crossed tolerance).
Elderly
Special caution should be exercised in elderly patients in the titration phase of treatment with clonazepam. Benzodiazepine pharmacologic effects appear to be greater in elderly patients. This could give rise to increased musclerelaxant effects (which could result in falls and fractures), increased cardiorespiratory effects and stronger adverse cognitive and sedative effects as compared to younger patients.
Hepatic impairment
Benzodiazepines can induce hepatic encephalopathy in patients with severe hepatic impairment. Therefore, caution and lowest possible dose should be used in treatment of patients with mild to moderate hepatic impairment (see section 4.2). Clonazepam is contraindicated in patients with severe hepatic impairment (see section 4.3).
History of alcohol or drug abuse
This medicine should be used with extreme caution in patients with a history of alcohol or drug abuse or in the event of acute intoxication with alcohol or drugs.
This medicinal product contains benzyl alcohol, ethanol and propylene glycol
Benzyl alcohol
This medicine contains 31 mg benzyl alcohol in each ampoule which is equivalent to 31 mg/ml.
Benzyl alcohol may cause allergic reactions.
Intravenous administration of benzyl alcohol has been associated with serious adverse events and death in neonates (“gasping syndrome”). The minimum amount of benzyl alcohol at which toxicity may occur is not known.
Increased risk due to accumulation in young children.
High volumes should be used with caution and only if necessary, especially in subjects with liver or kidney impairment, pregnant or breast-feeding women because of the risk of accumulation and toxicity (metabolic acidosis).
Ethanol
This medicine contains 80 % V/V ethanol (alcohol), ie up to 158 mg ethanol per dose, equivalent to 4 ml beer or 2 ml wine per dose.
A dose of 20 mg of this medicine administered to an adult weighing 70 kg would result in exposure to 45 mg/kg of ethanol which may cause a rise in blood alcohol concentration (BAC) of about 7.5 mg/100 ml (see Appendix 1 of report EMA/CHMP/43486/2018).
For comparison, for an adult drinking a glass of wine or 500 ml of beer, the BAC is likely to be about 50 mg/100 ml.
The amount of alcohol in this medicine is not likely to have an effect in adults and adolescents.
The alcohol in this medicine may alter the effects of other medicines. Co-administration with medicines containing e.g. propylene glycol or ethanol may lead to accumulation of ethanol and induce adverse effects in particular in young children with low or immature metabolic capacity.
If this medicine is given slowly over 2 hours, the effects of alcohol may be reduced.
Propylene glycol
This medicine contains 805 mg propylene glycol in each ampoule which is equivalent to 805 mg/ml.
Co-administration with any substrate for alcohol dehydrogenase such as ethanol may induce adverse effects in children less than 5 years old.
While propylene glycol has not been shown to cause reproductive or developmental toxicity in animals or humans, it may reach the foetus and was found in milk. As a consequence, administration of propylene glycol to pregnant or lactating patients should be considered on a case by case basis.
Medical monitoring is required in patients with impaired renal or hepatic functions because various adverse events attributed to propylene glycol have been reported such as renal dysfunction (acute tubular necrosis), acute renal failure and liver dysfunction.