clonazepam (Klonopin)
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Introduction
Tradename: Klonopin. DEA-controlled substance: class 4.
Indications
- absence (petit mal) seizures
- atypical absence seizures (Lennox-Gastaut)
- akinetic seizures
- myoclonic seizures
- neuralgia
- acute manic episodes
- restless legs syndrome
- multifocal tic disorder
- muscle spasms
- panic disorder
- rapid eye movement sleep behavioral disorder
- akasthisia[7]
- essential tremor[7]
Dosage
Tabs: 0.5, 1, 2 mg.
Pharmacokinetics
- well absorbed after oral administration
- onset of action 20-60 minutes
- duration of action 12 hours
- metabolized extensively by liver;
- metabolite 7-aminoclonazepam is active, but NOT an efficient anticonvulsant
- 1/2life 35 hours[5]
elimination via liver
elimination via kidney
1/2life = 20-60 hours
protein binding = 86 %
Adverse effects
- common (> 10%)
- drowsiness, fatigue, impaired coordination, ataxia, light- headedness, memory impairment, insomnia, dysarthria, anxiety, decreased libido, depression, headache, dry mouth, constipation, diarrhea, decreased salivation, nausea/vomiting, tachycardia, chest pain, blurred vision, sweating, rash, increased or decreased appetite
- less common (1-10%)
- uncommon (< 1%)
- menstrual irregularities, blood dyscrasias, reflex slowing, drug dependence
- other[5]
- drug adverse effects of anticonvulsants
- drug adverse effects of benzodiazepines
- drug adverse effects of psychotropic agents
- drug adverse effects of sedatives
Drug interactions
- may precipitate absence status if given with valproic acid
- disulfiram, nefazodone, fluoxetine, fluvoxamine, cimetidine, estrogens, erythromycin & grapefruit juice increase serum levels of clonazepam
- clonazepam may increase effects of CNS depressants
- phenytoin, phenobarbital, carbamazepine & rifampin increase metabolism of clonazepam
- flumazenil antagonizes effects of benzodiazepines
- drug interaction(s) anticonvulsants with anti-bacterial agents
- drug interaction(s) anticonvulsants with statins
- drug interaction(s) of methadone in combination with benzodiazepines
- drug interaction(s) of benzodiazepines with antidepressants
- drug interaction(s) of benzodiazepines with thiazide diuretics
- drug interaction(s) of antipsycotics with benzodiazepines
- drug interaction(s) of antidepressants with benzodiazepines
- drug interaction(s) of beta-adrenergic receptor antagonists with benzodiazepines
- drug interaction(s) of beta-adrenergic receptor antagonists (except atenolol) with benzodiazepines
- drug interaction(s) of alcoholic beverage with benzodiazepines
- drug interaction(s) of benzodiazepine with opiates
Laboratory
- specimen:
- methods: HPLC, GLC, RIA
- labs with loincs
- interferences:
- chlordiazepoxide may interfere with analysis by GLC
Mechanism of action
- potentiates inhibitory activity of GABA in the motor cortex
- increases neuronal membrane permeability to chloride
More general terms
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 701.
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 555
- ↑ Clinical Guide to Laboratory Tests, 3rd edition, NW Tietz ed, WB Saunders, Philadelphia, 1995
- ↑ 5.0 5.1 5.2 Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ 7.0 7.1 7.2 Deprecated Reference