Clonazepam is a high-potency, long-acting benzodiazepine derivative primarily used as an anticonvulsant and anxiolytic. It acts as a positive allosteric modulator at the GABA-A receptor, enhancing inhibitory neurotransmission in the central nervous system. The 0.25mg strength is a low-dose formulation, often used for initiation of therapy, in elderly patients, or for managing panic disorder.
Adult: Epilepsy: Initial: 0.5 mg at night, increased by 0.5 mg every 3 days. Maintenance: 1-4 mg/day in divided doses. Panic Disorder: Initial: 0.25 mg twice daily. Increase to 1 mg/day after 3 days. Target: 1-2 mg/day in divided doses. Max: 4 mg/day.
Note: Take with or without food. Swallow tablet whole with water. For panic disorder, divided doses (BID/TID) are common. For epilepsy, can be given as a single dose at bedtime or in divided doses. Do not crush or chew. Avoid grapefruit juice.
Clonazepam potentiates the effects of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system. It binds to a specific site (the benzodiazepine site) on the GABA-A receptor complex, which is a ligand-gated chloride channel. This binding increases the frequency of chloride channel opening events in response to GABA, leading to hyperpolarization of the neuronal membrane and reduced neuronal excitability.
Pregnancy: Pregnancy Category D (US FDA). Evidence of human fetal risk. Benzodiazepines cross the placenta. Associated with neonatal flaccidity, respiratory problems, and withdrawal symptoms. Use only if potential benefit justifies the risk. Avoid especially in first trimester and near term.
Driving: STRONGLY DISCOURAGED. Causes drowsiness, dizziness, and impaired coordination, reaction time, and vision. Effect may persist into the next day.
| Alcohol | Profound additive CNS and respiratory depression. | Major |
| Opioids (e.g., Codeine, Tramadol) | Increased risk of profound sedation, respiratory depression, coma, and death. | Major |
| Other CNS Depressants (Antipsychotics, Antihistamines, Barbiturates) | Additive sedation and impaired psychomotor performance. | Major |
| CYP3A4 Inhibitors (e.g., Ketoconazole, Itraconazole, Clarithromycin, Ritonavir) | Increase clonazepam levels, increasing toxicity risk. | Moderate |
| CYP3A4 Inducers (e.g., Carbamazepine, Phenytoin, Rifampicin, St. John's Wort) | Decrease clonazepam levels, reducing efficacy. | Moderate |
| Sodium Valproate/Valproic Acid | May potentiate absence seizures; complex interaction. | Moderate |
| Probenecid | May delay clonazepam metabolism. | Minor |