Clonazepam is in a group of drugs called benzodiazepines. Clonazepam affects chemicals in the brain that may become unbalanced and cause anxiety. Clonazepam is used to treat seizure disorders or panic disorder. Clonazepam may also be used for other purposes not listed in this medication guide.
Clonazepam is a benzodiazepine drug having anxiolytic, anticonvulsant, muscle relaxant, and hypnotic properties. Clonazepam has an unusually long half-life of 18-50 hours, making it generally considered to be among the long-acting benzodiazepines. Clonazepam is a chlorinated derivative of nitrazepam and therefore a chloro-nitrobenzodiazepine.
Benzodiazepines such as clonazepam have a fast onset of action and high effectiveness rate and low toxicity in overdose but have drawbacks due to adverse reactions including paradoxical effects, drowsiness, and cognitive impairment. Cognitive impairments can persist for at least six months after withdrawal of clonazepam; it is unclear whether full recovery of memory functions occurs. Other long-term effects of benzodiazepines include tolerance, benzodiazepine dependence, and benzodiazepine withdrawal syndrome, which occurs in a third of people treated with clonazepam for longer than four weeks.
Clonazepam is classified as a high potency benzodiazepine and is sometimes used as a second-line treatment of epilepsy. Clonazepam, like other benzodiazepines, while being a first-line treatment for acute seizures, is not suitable for the long-term treatment of seizures due to the development of tolerance to the anticonvulsant effects. The benzodiazepine clorazepate may be preferred over clonazepam due to a slower onset of tolerance and availability in slow-release formulation to counter fluctuations in blood levels. Clonazepam is also used for the treatment of panic disorder. The pharmacological property of clonazepam as with other benzodiazepines is the enhancement of the neurotransmitter GABA via modulation of the GABAA receptor.
Clonazepam may be prescribed for the following:
Epilepsy
Anxiety disorders
Panic disorder
Initial treatment of mania or acute psychosis together with firstline drugs such as lithium, haloperidol or risperidone
For the management of the visual effects of HPPD
Hyperekplexia
Many forms of parasomnia are sometimes treated with clonazepam. Restless legs syndrome can be treated using clonazepam as a third line treatment option as the use of clonazepam is still investigational. Bruxism also responds to clonazepam in the short-term Rapid eye movement behavior disorder responds well to low doses of clonazepam.
The treatment of acute and chronic akathisia induced by neuroleptics also called antipsychotics.
Spasticity related to amyotrophic lateral sclerosis
The effectiveness of clonazepam in the short-term treatment of panic disorder has been demonstrated in controlled clinical trials. Some long-term trials have suggested a benefit of clonazepam for up to three years without the development of tolerance but these trials were not placebo controlled. Clonazepam is also effective in the management of acute mania.
Clonazepam is sometimes used for certain rare childhood epilepsies and for refractory epilepsies; however, long-term prophylactic treatment of epilepsy has considerable limitations, the most notable ones being the loss of antiepileptic effects due to tolerance, which renders the drug ineffective with long term use which is why clonazepam and benzodiazepines as a class are, in general, to be prescribed only for the acute management of epilepsies. However, a subgroup of people with treatment resistant epilepsy may benefit from long-term use of clonazepam; the benzodiazepine clorazepate may be preferred however, due to its slower onset of tolerance.
Clonazepam or diazepam has been found to be effective in the acute control of nonconvulsive status epilepticus. However, the benefits tended to be transient in many of the patients, and the addition of phenytoin for lasting control was required in these patients.
In general, clonazepam has been found to be ineffective in the control of infantile spasms.
Clonazepam is less effective and potent as an anticonvulsant in bringing infantile seizures under control compared with nitrazepam in the treatment of West syndrome, which is an age-dependent epilepsy affecting the very young. However, as with other epilepsies treated with benzodiazepines, long-term therapy becomes ineffective with prolonged therapy, and the side effects of hypotonia and drowsiness are troublesome with clonazepam therapy; other antiepileptic agents are, therefore, recommended for long-term therapy, possibly Corticotropin (ACTH) or vigabatrin. Furthermore, clonazepam is not recommended for widespread use in the management of seizures related to West syndrome.
Clonazepam has shown itself to be highly effective as a short-term (3 weeks) adjunct to SSRI treatment in obsessive-compulsive disorder and clinical depression in reducing SSRI side effects with the combination being superior to SSRI treatment alone in a study funded by the manufacturers of clonazepam, Hoffman LaRoche Inc.
Side effects that you should report to your doctor or health care professional as soon as possible:
allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
changes in vision
confusion
depression
hallucinations
mood changes, excitability or aggressive behavior
movement difficulty, staggering or jerky movements
muscle cramps, weakness
tremors
unusual eye movements
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
constipation or diarrhea
difficulty sleeping, nightmares
dizziness, drowsiness
headache
increased saliva from your mouth
nausea, vomiting
This list may not describe all possible side effects. Call your doctor for medical advice about side effects.
You must not use Clonazepam during pregnancy or if you are trying to become pregnant due to possible harm to the unborn baby and interference with normal labor/delivery.
Talk to your doctor or healthcare provider before using this drug. Clonazepam is excreted into human milk in small amounts. No adverse effects have been reported in nursing infants, but experience is quite limited. The American Academy of Pediatrics has no position on the use of clonazepam during breast-feeding but describes other benzodiazepines as drugs "whose effect on nursing infants is unknown but may be of concern".
Cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for depression or anxiety can add to sleepiness caused by clonazepam. Tell your doctor if you regularly use any of these medicines, or any other seizure medications or benzodiazepines.
Also tell your doctor if you are using any of the following drugs:
propantheline (Pro-Banthine);
an antibiotic such as clarithromycin (Biaxin), dalfopristin/quinupristin (Synercid), erythromycin (E.E.S., EryPed, Ery-Tab, Erythrocin, Pediazole), or telithromycin (Ketek);
an antifungal medicine such as fluconazole (Diflucan), itraconazole (Sporanox), ketoconazole (Nizoral), or voriconazole (Vfend);
an antidepressant such as amitriptyline (Elavil, Vanatrip, Limbitrol), doxepin (Sinequan), nefazodone, nortriptyline (Pamelor), and others;
a barbiturate such as butabarbital (Butisol), secobarbital (Seconal), pentobarbital (Nembutal), or phenobarbital (Solfoton);
an MAO inhibitor such as furazolidone (Furoxone), isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam, Zelapar), or tranylcypromine (Parnate); or
medicines to treat psychiatric disorders, such as chlorpromazine (Thorazine), droperidol (Inapsine), haloperidol (Haldol), mesoridazine (Serentil), pimozide (Orap), thioridazine (Mellaril), or thiothixene (Navane).
This list is not complete and other drugs may interact with clonazepam. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.
Usual Clonazepam Adult Dose for Seizure Prophylaxis:
Initial dose: 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 until side effects preclude any further increase.
Maintenance dose: Individualized for each patient depending upon response.
Maximum Daily Dose: 20 mg.
Usual Adult Clonazepam Dose for Bipolar Disorder:
Initial dose: 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 until side effects preclude any further increase.
Maintenance dose: Individualized for each patient depending upon response.
Maximum Daily Dose: 20 mg.
Usual Adult Clonazepam Dose for Panic Disorder:
Initial dose: 0.25 mg bid.
Maintenance dose: An increase to the target dose for most patients of 1 mg/day may be made after 3 days.
The dose may be increased in increments of 0.125 to 0.25 mg bid every 3 days until panic disorder is controlled or until side effects make further increases undesired. To reduce the inconvenience of somnolence, administration of one dose at bedtime may be desirable.
Maximum Dose: 4 mg/day
Treatment should be discontinued gradually, with a decrease of 0.125 mg bid every 3 days, until the drug is completely withdrawn.
Usual Pediatric Clonazepam Dose for Seizure Prophylaxis:
<= 10 years or < 30 kg of body weight:
Initial Dose: Orally:
In order to minimize drowsiness, the initial dose 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.
Dosage should be increased by no more than 0.25 to 0.5 mg every third day until a daily maintenance dose of 0.1 to 0.2 mg/kg of body weight has been reached, unless seizures are controlled or side effects preclude further increase. Whenever possible, the daily dose should be divided into three equal doses. If doses are not equally divided, the largest dose should be given before retiring.
>10 years and >30 kg of body weight:
The initial dose 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 until side effects preclude any further increase.
The maintenance dosage should be individualized for each patient depending upon response.
Maximum Daily Dose: 20 mg.