Clonazepam is used for the treatment of panic disorder, with or without agoraphobia. Panic disorder involves sudden and unexpected panic attacks along with persistent concern about having more attacks and worry about their consequences.

Clonazepam is also indicated as a single therapy or as an add-on treatment for Lennox–Gastaut Syndrome (petit mal variant), akinetic and myoclonic seizures. It may also be used in patients with absence seizures (petit mal) who do not respond adequately to succinimides.

The long-term effectiveness of Clonazepam (beyond 9 weeks) has not been fully established in controlled clinical studies. Physicians prescribing it for extended use should regularly reassess its benefits for each individual patient.

Clonazepam has pharmacological actions typical of benzodiazepines, including anticonvulsant, sedative, muscle relaxant, and anxiolytic effects. Its central effects are produced by enhancing GABA-mediated neurotransmission at inhibitory synapses. Benzodiazepines increase the affinity of GABA receptors for the neurotransmitter, leading to greater chloride ion influx across the postsynaptic membrane and resulting in enhanced inhibitory effects.

Studies in animals also suggest that clonazepam may influence serotonin activity. Clinical and EEG findings in humans show that clonazepam can quickly suppress various types of abnormal electrical brain activity, including spike and wave discharges in absence seizures (petit mal), slow spike-wave patterns, generalized spike-wave discharges, and irregular spikes. Generalized EEG abnormalities tend to respond better than focal abnormalities, indicating clonazepam’s usefulness in both generalized and focal epilepsies.

Oral:

• Adults: The initial dose for adults with seizure disorders should not exceed 1.5 mg/day divided into three doses. Dosage may be increased in increments of 0.5 to 1 mg every 3 days until seizures are adequately controlled or side effects preclude any further increase. Maintenance dosage must be individualized for each patient depending upon response. Maximum recommended daily dose is 20 mg.
• The initial dose for adults with panic disorder is 0.25 mg given in two divided dose. An increase to the target dose for most patients of 1 mg/day may be made after 3 days.
• Pediatric Patients: In order to minimize drowsiness, the initial dose for infants and children (up to 10 years of age or 30 kg of body weight) should be between 0.01 and 0.03 mg/kg/day but not to exceed 0.05 mg/kg/day given in two or three divided doses.

Injection:

• Infants and children: half of a vial (0.5 mg) by slow IV injection or by IV infusion.
• Adults: 1 vial (1 mg) by slow IV injection or by IV infusion. This dose can be repeated as required (1–4 mg are usually sufficient to reverse the status). In adults, the rate of injection must not exceed 0.25 – 0.5 mg per minute (0.5–1.0 ml of the prepared solution) and a total dose of 10 mg should not be exceeded.

Clonazepam does not significantly affect the pharmacokinetics of phenytoin, carbamazepine, or phenobarbital. Its influence on the metabolism of other medications has not been fully studied.

Clonazepam should not be used in patients with a known hypersensitivity to benzodiazepines or in those with clinical or biochemical evidence of significant liver disease. It may be used cautiously in patients with open-angle glaucoma receiving proper treatment but is contraindicated in acute narrow-angle glaucoma.

The most common side effects of Clonazepam are related to central nervous system depression. Clinical experience shows that drowsiness occurs in about 50% of patients and ataxia in around 30%. These effects may decrease over time. Behavioral disturbances have been reported in approximately 25% of patients. Other possible effects include abnormal eye movements, aphonia, coma, tremor, vertigo, confusion, depression, amnesia, hallucinations, hysteria, increased libido, insomnia, psychosis, and palpitations.

Pregnancy: Preclinical studies suggest that clonazepam may carry a risk of causing congenital abnormalities. Epidemiological data indicate that anticonvulsant drugs may act as teratogens, although it is difficult to determine the exact cause of birth defects due to multiple contributing factors such as genetics or the underlying disease. Therefore, clonazepam should only be used during pregnancy if the expected benefit outweighs the potential risk to the fetus. Use of high doses in late pregnancy or during labor may cause irregular fetal heart rate, hypothermia, hypotonia, mild respiratory depression, and feeding difficulties in the newborn. Both abrupt discontinuation and continued use may worsen epilepsy. Withdrawal symptoms in newborns have occasionally been reported.

Nursing Mothers: Clonazepam passes into breast milk in small amounts. Mothers receiving this medication are generally advised not to breastfeed. If treatment is essential, breastfeeding should be discontinued.

In patients with multiple types of seizure disorders, Clonazepam may increase the frequency or trigger the onset of generalized tonic-clonic seizures. This may require adding appropriate anticonvulsants or adjusting their doses. Concurrent use with valproic acid may lead to absence status.

Pediatric Use: In infants and young children, Clonazepam may increase saliva and bronchial secretions. Careful monitoring is needed to maintain airway patency.

Geriatric Use: Elderly patients may experience stronger benzodiazepine effects compared to younger individuals, possibly due to age-related changes in drug-receptor interaction and organ function.

Renal Impairment: Kidney impairment does not significantly affect clonazepam pharmacokinetics, and dose adjustment is usually not required.

Hepatic Impairment: Plasma protein binding of clonazepam is altered in patients with liver cirrhosis. Although detailed studies are limited, evidence from related drugs suggests that clearance of unbound clonazepam may be reduced in such conditions.

Symptoms: Benzodiazepines commonly cause drowsiness, ataxia, dysarthria, and nystagmus. Overdose of clonazepam is rarely life-threatening when taken alone, but it may result in areflexia, apnoea, hypotension, cardiorespiratory depression, and coma. If these occur, they usually last for several hours but may persist longer and become cyclical, especially in elderly patients. Increased seizure frequency may be seen in patients taking higher-than-recommended doses. Respiratory depression from benzodiazepines can be more severe in patients with respiratory disease. These drugs may also enhance the effects of other central nervous system depressants, including alcohol.

Treatment: Monitor vital signs and provide supportive care according to the patient’s clinical condition. Patients may require symptomatic treatment for cardiorespiratory or central nervous system effects. Further absorption should be prevented using appropriate methods, such as administering activated charcoal within 1–2 hours. If charcoal is used, airway protection is essential in drowsy patients. In mixed overdose cases, gastric lavage may be considered, although it is not routinely recommended. In severe central nervous system depression, consider using flumazenil (a benzodiazepine antagonist). However, it should be used cautiously in patients taking drugs that lower seizure threshold (e.g., tricyclic antidepressants). Refer to prescribing information for proper use of flumazenil.

Adjunct anti-epileptic drugs, Benzodiazepine hypnotics

Store in a cool, dry place away from light and heat. Keep out of reach of children.