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Clonazepam

Brands and Forms

  • Klonopin
    • tablet: 0.5mg, 1mg, 2mg
    • orally disintegrating tablet: 0.125mg, 0.25mg, 0.5mg, 1mg, 2mg
  • Rivotril
    • tablet: 0.5mg, 1mg, 2mg

Uses of Clonazepam

Clonazepam is used to treat states of anxiety, restlessness, agitation, and insomnia that can occur in a variety of psychiatric conditions, especially Anxiety Disorders. It cen be effective as monotherapy (ie. it can be used on its own without other medications) for Generalized Anxiety Disorder, Panic Disorder and Social Phobia, though in clinical practice it is more common for Clonazepam to be used in combination with other medications, and mainly in instances where extra help is needed to control symptoms of anxiety, restlessness, agitation, and insomnia.

In general medicine, Clonazepam is also used for treating seizure disorders and for inducing sedation during surgical procedures.

How Clonazepam Works

Clonazepam is a benzodiazepine. It enhances the effects of GABA in the central nervous system by binding to GABA-A channels and making these channels more receptive to the actions of the brain's naturally occurring GABA.

Clonazepam tends to produce a clinical effect lasting about 4-8 hours.

Cautions when Using Clonazepam

Regular Clonazepam use over a period of a few weeks can lead to tolerance, dependence and abuse. Ideally, this medication should be avoided in individuals with histories of substance abuse, or else used only with very close monitoring by the prescribing physician.

Caution should be used when Clonazepam is taken by elderly individuals, as this medication can cause memory and concentration difficulties as well as confusion in these individuals, and also make them more prone to falls.

Stopping Clonazepam abruptly after long-term regular use can lead to serious and potentially life-threatening withdrawal symptoms.

Clonazepam should not be used by individuals with obstructive sleep apnea, especially if positive airway pressure (C-PAP) treatments are not being used, as this could lead to prolonged periods of apnea. Use with caution in individuals with other kinds of respiratory disease.

Clonazepam should not be combined with alcohol due to the risk of excessive CNS depression.

People should not drive or operate heavy machinery while taking Clonazepam.

Clonazepam should not be used by individuals with narrow angle-closure glaucoma or severe liver disease.

Dosing of Clonazepam

When used on an as-needed basis for episodic symptoms of anxiety, restlessness, agitation or insomnia, the recommended starting dose of Clonazepam is 0.25-0.5mg. Higher doses should be used only if it is found that the initial dose is not effective. At any dose, this medication can be expected to produce its effects within 30min and to last for 4-8 hours.

When used to control symptoms of anxiety or restlessness throughout the day, the recommended starting dose is 0.5-1mg/day, given in divided doses twice daily. Depending on the clinical effects, the dose can be increased by as much as 1mg/day every 3 days. Usually 2mg/day is required, but in some cases as much as 4mg/day may be needed.

When wanted to stop Clonazepam after it has been used regularly for a prolonged period, the dose should be tapered gradually over a period of a few weeks so as to prevent the occurence of withdrawal symptoms.

When wanting to switch Clonazepam to a different benzodiazepine, please refer to the Benzodiazepine Equivalency Table for information on dose conversion.

Onset of action

Therapeutic effects are immediate.

Kidney impairment

Lower dose and use with caution.

Liver impairment

Lower dose and use with caution.

Side-effects of Clonazepam

Below is a list of most of the reported side-effects of Clonazepam. Most of these side-effects occur in only a minority of individuals, and many also resolve with time while the medication is continued.

Cardiovascular: tachycardia; hypotension; palpitations.

Central Nervous System: drowsiness; fatigue/tiredness; sedation; memory impairment; cognitive impairment; light-headedness; decreased libido; dysarthria; confusional state; abnormal coordination; unsteadiness; disturbed attention; disorientation, paresthesia; dyskinesia; talkativeness; abnormal dreams; lethargy; hypesthesia; hypersomnia; malaise; weakness; headache; dizziness; tremor; insomnia; nightmares.

Dermatologic: rash.

Eyes, Ears, Nose and Throat: pharyngitis; blurred vision; hearing disturbances.

Gastrointestinal: constipation; diarrhea; dry mouth; coated tongue; excessive salivation; nausea; loss of appetite; vomiting; elevated liver enzymes; liver impairment (rare).

Genitourinary: abnormal menstruation; colpitis; impotence; urinary frequency; delayed ejaculation; urinary retention; enuresis; painful urination.

Hematologic: blood dyscrasias (including agranulocytosis, anemia, thrombocytopenia, leukopenia, neutropenia).

Psychiatric: depressed mood; apathy; disinhibitted behavior; dissociative symptoms; irritability (usually from withdrawal); anxiety (usually from withdrawal); restlessness (usually from withdrawal); mania (very rare); psychosis (very rare).

Respiratory: upper respiratory tract infection; sinusitis; rhinitis; coughing; respiratory depression.

Common side-effects of Clonazepam

Somnolence, dizziness, unsteadiness, imparied coordination, slowed thinking and reaction time.

Rare but serious side-effects of note of Clonazepam

  • Liver damage can occur in very rare cases.
  • Blood dyscrasias (including agranulocytosis, anemia, thrombocytopenia, leukopenia, neutropenia) can occur very rarely.
  • See cautions above.

Clonazepam withdrawal

Individuals who take Clonazepam regularly over a period of a few weeks are at risk of developing a withdrawal syndrome if they stop the medication abruptly. The severity of the withdrawal symptoms will be proportional to the size of the Clonazepam dose that was being used on a regular basis. With heavy use, most of the following symptoms could occur:

In the first stages of this syndrome, the individual will experience tremors, autonomic hyperactivity (sweating, fever, elevated blood pressure, rapid heart rate), anxiety, agitation, nausea, vomiting, and insomnia.

If left untreated, the next symptoms to appear are confusion and disorientation, hallucinations (mainly visual ones, but also auditory, tactile and olfactory) and delusions.

Seizures and cardiovascular collapse can then ensue, and are the most concerning symptoms.

This syndrome is considered a medical emergency. The main treatment is to restart the Clonazepam at the most recent dose, or to switch it to the equivalent of another longer-acting benzodiazepine such as Diazepam.

To prevent this syndrome, the dose of the medication should be reduced gradually over a period of a few weeks. If withdrawal symptoms make even a gradual taper difficult, it would be recommended to switch to a longer-acting benzodiazepine such as Diazepam, which would then be tapered gradually.

Clonazepam overdose

Somnolence, confusion, impaired coordination, diminished reflexes, coma. Can be fatal in very rare cases.

Clonazepam and pregnancy

Category D: benzodiazepines such as Clonazepam have been associated with a risk of less than 1% of causing cleft lip or palette to the fetus when used in pregnancy [ref]. A fetus exposed to benzodiazepines in utero is also at risk for developing a withdrawal syndrome shortly after birth, which would require medical treatment.

Clonazepam should only be used in pregnancy if clearly needed and if benefits outweigh potential risks. However, because the effects of Diazepam in pregnancy have been more closely studied, it would be prudent to use Diazepam if a benzodiazepines is required during pregnancy [ref].

Medical Monitoring for Clonazepam

Individuals taking Clonazepam over prolonged periods of time should have their liver functions and complete blood counts measured periodically.

Drug Interactions with Clonazepam

  • Clonazepam should not be combined with alcohol due to the risk of excessive CNS depression.
  • Use caution when combining Clonazepam with other medications that can cause sedation or CNS depression.
  • The effects of Clonazepam can be intensified by Cimetidine, disulfiram, and oral contraceptives
  • Clonazepam blood concentrations can be decreased by Carbamazepine, Phenytoin and Rifampin.
  • Clonazepam can increase blood concentrations of Digoxin.