Clonazepam
From Freepedia
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Image:Clonazepam.jpg | |
| 5-(2-chlorophenyl)-1,3-dihydro- 7-nitro-2H-1,4-benzodiazepine-2-one | |
| CAS number 1622-61-3 | ATC code N03AE01 |
| Chemical formula | C15H10ClN3O3 |
| Molecular weight | 315.715 |
| Bioavailability | 90% |
| Metabolism | Hepatic |
| Elimination half-life | 30-40 hours |
| Excretion | Renal |
| Pregnancy category | D |
| Legal status | Schedule IV Drug |
| Routes of administration | Intravenous, tablets 0.5 mcg, 1 mcg, and 2 mcg |
Clonazepam (marketed by Roche under the trade-name Klonopin® in the United States and Rivotril® in Canada and Europe) is an anticonvulsant sedative-hypnotic anxiolytic (anti-anxiety drug), and a member of the benzodiazepine class of drugs. Like other benzodiazepines, Clonazepam is believed to act by simulating the action of GABA on the central nervous system. Because of strong anxiolytic properties and euphoriant side-effects it is said to be among the class of 'high potent' benzodiazepines with a higher risk of abuse, missuse and dependence than other benzodiazepines. The sedative effects of Clonazepam are relatively weak, compared to its strong anxiolytic and anticonvulsant effectivity. Two hundred and fifty micrograms (0.25mg) are equivalent to 5mg Diazepam.
Clonazepam was approved in the United States as a generic medication in 1997 and is now manufactured and marketed by several companies.
Contents |
Common uses
Clonazepam is used as a treatment, but not a cure for the conditions below.
- seizures, epilepsy
- anxiety disorder and panic disorder
- restless leg syndrome (RLS)
- inital treatment of mania together with firstline-drugs like Lithium, Valproate or neuroleptics
- hallucinogen persisting perception disorder (unlicenced use, efficacy reported in case reports)
- night terrors
Treamtment of insomnia with Clonazepam is uncommon, because the sedative effects of Clonazepam are relatively weak. Better alterntives are e.g. Zopiclon, Zolpidem or Diazepam.
Contraindications
All general contraindications to benzodiazepines apply. These are:
absolute
- myasthenia gravis
- acute intoxications with alcohol, narcotics, and psychoactive drugs
- ataxia
- severe respiratory insufficience
- severe liver insufficience (drug elimination is greatly decreased)
- attacks of apnea during sleep
special caution needed
- children and aldolescents (< 18 yrs. of age) : treatment usually not indicated, except treatment of epilepsy, and pre-/postoperative treatment; extended clinical experience in this group of age is lacking! Try pschyotherapeutic methods first!
- patients with a history of drug- or alcohol misuse or dependence : monitor these patients closely!
- i.v.-injections in hypotensive patients or those in shock
Side Effects
Because Clonazepam can impair both mental and motor function, those taking it are typically advised to use caution when operating machinery, motor vehicles, or engaging in hazardous occupations requiring mental alertness.
- drowsiness
- depression
- impaired motor function / coordination
- impaired balance
- dizziness
- nervousness
- anterograde amnesia (especially pronounced in higher doses)
It should be noted that up to 30% treated on a long-term basis develop a form of dependence known as 'low-dose-dependence', i.e. these patients do not need increasing doses to experience the feeling of 'well-beeing' caused by the drug.
Use of alcohol or other tranqulizing medication while taking Clonazepam is known to intensify its effects.
Dosage recommendations
In cases of status epilepticus 1mg is given slowly i.v., if seizures persist additional doses of 1mg may be given in intervals of 10 to 20 minutes.
In the long-term treatment of epilepsy it is particular useful in treating children and aldolescents with some petit-mal forms. But also adults may respond well. N.B. Up to 30% of epileptic patients develop serious tolerance to the anticonvulsive actions, requirering upward dose adjustments or gradual withdrawal of the drug. Oral doses in epilepsy may vary depending upon the severity of case and the weight of the patient from 1mg to 20mg in long-term therapy. Intial doses should be low and be increased gradually.
Other indications:
- anxiety and panic disorders: 1 to 10mg daily in divided doses
- RLS : bedtime dose of 1-2mg
- mania : initially high daily doses of up to 20mg in divided doses are needed
Taking clonazepam
Clonazepam may cause both psychological and physical dependence. As a result, persons with a history of substance abuse are advised to discuss this with the prescribing physician prior to starting the medication.
Discontinuation effects
People who have been taking Clonazepam for longer than 1-2 weeks may experience withdrawal symptoms which are similar to those experienced when barbiturates are stopped. For persons taking Clonazepam longer than 1-2 weeks, discontinuation should be done under the supervision of a medical professional. To minimize withdrawal effects, the dose should be gradually lowered over time.
Dose Forms
- tablets 0.5, 1.0, and 2mg
- liquid concentrate (2.5mg per ml)
- injection concentrate (1mg)
Overdose
A person who has consumed too much Clonazepam will have the following symptoms: difficulty staying awake, mental confusion, coma, and diminished reflexes. Overdose of Clonazepam constitutes a medical emergency and requires the immediate attention of emergency medical personnel. Its antidote is flumazenil.
External links
- FDA prescribing insert: http://www.fda.gov/cder/foi/label/2001/17533s31lbl.PDF
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