Clonazepam

Class: Benzodiazepines
VA Class: CN400
CAS Number: 1622-61-3
Brands: Klonopin

REMS:

FDA approved a REMS for clonazepam to ensure that the benefits of a drug outweigh the risks. The REMS may apply to one or more preparations of clonazepam and consists of the following: medication guide. See the FDA REMS page () or the ASHP REMS Resource Center ().

Introduction

Benzodiazepine; anticonvulsant, sedative, and anxiolytic.^{1 b}

Uses for Clonazepam

Seizure Disorders

Prophylactic management of Lennox-Gastaut syndrome and akinetic and myoclonic seizures.^{1 b d}

Management of absence seizures in patients unresponsive to succinimides.^{1 b d}

Some evidence of success in the management of refractory seizures†, including partial seizures with complex symptomatology and other partial seizures and some cases of infantile spasms†.^{b d}

Useful in some patients with tonic-clonic seizures†.^{b d}

Panic Disorder

Treatment of panic disorder with or without agoraphobia.^{1 3}

Catatonia

Also has been used for treatment of acute catatonic reactions†, whether associated with schizophrenia or other conditions.

Akathisia

May be helpful in patients experiencing akathisia† while receiving antipsychotic drugs (e.g., for management of schizophrenia).

Clonazepam Dosage and Administration

General

• 
  

  Adjust dosage carefully and slowly according to individual requirements and response.^b

  
  


• 
  

  Withdraw clonazepam slowly; avoid abrupt discontinuance, especially during long-term, high-dose therapy, to avoid precipitating seizures, status epilepticus, or withdrawal symptoms.^b During withdrawal of clonazepam in patients with seizure disorders, simultaneous substitution of another anticonvulsant may be indicated.^b

  
  

Administration

Oral Administration

Administer orally as conventional or orally disintegrating tablets.^a

Administer in 3 equally divided doses for the treatment of seizure disorders; if doses are not equally divided, give the largest dose at bedtime.^{1 b}

Administer in 2 equally divided doses for the management of panic disorder; alternatively, administer the entire dosage at bedtime to reduce the inconvenience of somnolence.^{1 b}

Conventional Tablets

Swallow tablet whole with water.^a

Orally Disintegrating Tablets

Just prior to administration, remove blister from aluminum pouch; with dry hands, peel open blister package, place orally disintegrating tablet in mouth to dissolve, and swallow with or without water.^a

Dosage

Pediatric Patients

Seizure Disorders

Oral

Infants and children <10 years of age or weighing <30 kg: Initially, 0.01–0.03 mg/kg daily; initial dosage should not exceed 0.05 mg/kg daily given in 2 or 3 divided doses.¹

Increase dosage by no more than 0.5 mg every third day until seizure control is achieved with minimal adverse effects.¹ Maintenance dosage of 0.1–0.2 mg/kg daily.¹

Children ≥10 years of age or weighing ≥30 kg: Initial dosage should not exceed 1.5 mg daily given in 3 divided doses.^{1 e}

Increase dosage in increments of 0.5–1 mg every third day (up to a maximum dosage of 20 mg daily) until seizure control is achieved with minimal adverse effects.^{1 e}

Adults

Seizure Disorders

Oral

Initial dosage should not exceed 1.5 mg daily given in 3 divided doses.^{1 b} Increase dosage in increments of 0.5–1 mg every third day (up to a maximum dosage of 20 mg daily) until seizure control is achieved with minimal adverse effects.^{1 b}

Panic Disorder

Oral

Initially, 0.25 mg twice daily.¹ After 3 days, increase dosage to usual maintenance dosage of 1 mg daily.¹

Some clinicians recommend dosages of 1–2 mg daily.³ Certain patients may benefit from dosages up to 4 mg daily.¹ In such cases, increase dosage by 0.125–0.25 mg twice daily every 3 days until panic disorder is controlled with minimal adverse effects.¹

Discontinue therapy gradually by decreasing the dosage in increments of 0.125 mg twice daily every 3 days until the drug is completely withdrawn.¹

Prescribing Limits

Pediatric Patients

Seizure Disorders

Oral

Maximum 0.2 mg/kg daily.^b

Adults

Seizure Disorders

Oral

Maximum 20 mg daily.¹

Panic Disorder

Oral

Maximum 4 mg daily.¹

Special Populations

Geriatric Patients

Initiate therapy at low dosage and observe closely.^a

Cautions for Clonazepam

Contraindications

• 
  

  Known hypersensitivity to clonazepam or other benzodiazepines.¹

  
  


• 
  

  Clinical or biochemical evidence of substantial hepatic impairment.¹

  
  


• 
  

  Manufacturer states that clonazepam is contraindicated in patients with acute angle-closure glaucoma but may be administered to patients with open-angle glaucoma who are receiving appropriate therapy;¹ however, clinical rationale for this contraindication has been questioned.^c

  
  

Warnings/Precautions

Warnings

CNS Effects

Performance of activities requiring mental alertness and physical coordination may be impaired.¹

Concurrent use of other CNS depressants may potentiate CNS depression.¹ (See Specific Drugs under Interactions.)

Withdrawal Effects

Abrupt discontinuance may result in symptoms of withdrawal (similar to barbiturates or alcohol).^{1 8} Symptoms may be relieved by tapering the dosage.¹

General Precautions

Seizure Disorders

May increase the incidence or precipitate the onset of generalized tonic-clonic seizures in patients with multiple types of seizure disorders.¹ Consider addition of appropriate anticonvulsants or an increase in their dosages.¹

Abrupt withdrawal, particularly in patients receiving long-term, high-dose therapy, may result in status epilepticus.¹

Concomitant use with valproic acid may produce absence status.¹

Laboratory Testing

Perform blood counts and liver function tests periodically during long-term therapy.¹

Hypersalivation

May increase salivation; use with caution in patients who have difficulty tolerating or clearing secretions.¹

Respiratory Effects

Possible hypersalivation and respiratory depression in patients with chronic respiratory disease; use with caution in such patients.^{1 b}

Abuse Potential

Psychologic and physical dependence may occur following prolonged use.¹

Patients with a history of drug or alcohol dependence or abuse are at risk of habituation or dependence; use only with careful surveillance in such patients.¹

Suicide

Use with caution in depressed patients; potential for suicidal tendencies.^c Prescribe drug in the smallest feasible quantity.^c

Psychiatric Indications

Do not use in patients with depressive neuroses or psychotic reactions in which anxiety is not prominent.^c

Specific Populations

Pregnancy

Category D.¹

Lactation

Distributed into milk;^c discontinue nursing or the drug.¹

Pediatric Use

Effects of long-term administration on physical and mental development have not been established.^{1 b} Administer to children with seizure disorders only if potential benefits outweigh possible risks.^{1 b}

Safety and efficacy for treatment of panic disorder not established in children <18 years of age;¹ however, clonazepam has been effective in a limited number of adolescents with panic disorder.²²

Geriatric Use

Insufficient experience from clinical studies to determine whether patients ≥65 years of age respond differently than younger adults.^a Other clinical experience has not identified age-related differences in responses. Potential increased sensitivity (increased risk of oversedation and confusion) to sedatives.^a

Select dosage carefully, generally initiating therapy at low dosage; observe closely.^a Consider the increased incidence of hepatic and renal impairment, decreased cardiac function, and concomitant disease and drug therapy in the geriatric population.^a May be useful to assess hepatic and/or renal function when selecting dosage.^a

Hepatic Impairment

Prolonged elimination.^{1 c} Contraindicated in patients with clinical or biochemical evidence of substantial liver disease.¹

Renal Impairment

Elimination of metabolites may be decreased; use with caution.¹

Common Adverse Effects

Sedation/drowsiness, ataxia/hypotonia, behavioral disturbances (principally in children) including aggressiveness, irritability, agitation, hyperkinesis.^b

Interactions for Clonazepam

Metabolized by CYP enzymes, including CYP3A.¹

Drugs Affecting or Affected by Hepatic Microsomal Enzymes

Potential pharmacokinetic interaction (altered plasma concentrations of clonazepam) with CYP inducers or inhibitors.¹

No evidence that clonazepam induces metabolism of other drugs.^a

Specific Drugs

Drug	Interaction	Comments
Antifungal agents, azole-type (e.g., itraconazole, ketoconazole)	Possible increase in plasma clonazepam concentrationsa	Use with caution1
Carbamazepine	Decreased plasma clonazepam concentrations; carbamazepine pharmacokinetics not affecteda
CNS depressants (e.g., opiates or other analgesics, barbiturates, sedatives, anticonvulsants, alcohol)	Additive CNS effects1 b	Use caution to avoid overdosageb
Disulfiram	Possible increase in plasma clonazepam concentrations	Reduce clonazepam dosage as necessary
Fluoxetine	Clonazepam pharmacokinetics not affecteda
Phenobarbital	Decreased plasma clonazepam concentrations; phenobarbital pharmacokinetics not affecteda
Phenytoin	Decreased plasma clonazepam concentrations; phenytoin pharmacokinetics not affecteda
Propantheline	Possible decrease in plasma clonazepam concentrationsa

Clonazepam Pharmacokinetics

Absorption

Bioavailability

Rapidly and completely absorbed following oral administration, with peak concentrations achieved within 1–4 hours.¹ Absolute bioavailability is approximately 90%.¹

Onset

Anticonvulsant action occurs within 20–60 minutes following oral administration.^b

Duration

Duration of anticonvulsant action is 6–8 hours in infants and young children and up to 12 hours in adults.^b

Distribution

Extent

Apparently crosses the blood-brain barrier and the placenta.^b

Plasma Protein Binding

Approximately 85%.¹

Elimination

Metabolism

Extensively metabolized in the liver to several metabolites.^b

Elimination Route

Excreted in urine (<2% as unchanged drug).^{b 1}

Half-life

18–50 hours.^{1 b c}

Stability

Storage

Oral

Conventional or Orally Disintegrating Tablets

25°C (may be exposed to 15–30°C).^a

Actions

• 
  

  Exact mechanism of anticonvulsant, sedative, and antipanic effects is unknown;¹ however, mechanism appears to be related to the drug’s ability to enhance the activity of GABA, the principal inhibitory neurotransmitter in the CNS.^{1 b}

  
  

Advice to Patients

• 
  

  Importance of taking only as prescribed; do not increase dosage or duration of therapy unless otherwise instructed by a clinician.¹

  
  


• 
  

  Importance of not abruptly discontinuing therapy; consult clinician about discontinuing use.¹

  
  


• 
  

  Potential for psychologic or physiologic dependence.¹

  
  


• 
  

  Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, and concomitant illnesses, particularly depression.¹

  
  


• 
  

  Importance of avoiding alcohol-containing beverages or products.¹

  
  


• 
  

  Potential for drug to impair mental alertness or physical coordination; avoid driving or operating machinery until effects on individual are known.¹

  
  


• 
  

  Importance of informing clinicians of any behavioral or mental changes, memory impairment, tolerance, or dependence/withdrawal symptoms.^c

  
  


• 
  

  Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.¹

  
  


• 
  

  Importance of informing patients of other important precautionary information.¹ (See Cautions.)

  
  

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Subject to control under the Federal Controlled Substances Act of 1970 as a schedule IV (C-IV) drug.¹

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Clonazepam

Routes	Dosage Forms	Strengths	Brand Names	Manufacturer
Oral	Tablets	0.5 mg*	Klonopin (C-IV; scored)	Roche
		1 mg*	Klonopin (C-IV)	Roche
		2 mg*	Klonopin (C-IV)	Roche
	Tablets, orally disintegrating	0.125 mg*	Klonopin Wafers (C-IV; with parabens)	Roche
		0.25 mg*	Klonopin Wafers (C-IV; with parabens)	Roche
		0.5 mg*	Klonopin Wafers (C-IV; with parabens)	Roche
		1 mg*	Klonopin Wafers (C-IV; with parabens)	Roche
		2 mg*	Klonopin Wafers (C-IV; with parabens)	Roche

Comparative Pricing

This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 10/2011. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.

ClonazePAM 0.5MG Tablets (ACTAVIS ELIZABETH): 30/$13.99 or 90/$26.99

ClonazePAM 1MG Tablets (ACTAVIS ELIZABETH): 30/$11.99 or 90/$26.99

ClonazePAM 2MG Tablets (SANDOZ): 30/$12.99 or 90/$23.99

ClonazePAM ODT 0.125MG Dispersible Tablets (PAR): 60/$69.99 or 180/$189.98

ClonazePAM ODT 0.25MG Dispersible Tablets (PAR): 60/$72.99 or 180/$207.98

ClonazePAM ODT 0.5MG Dispersible Tablets (PAR): 60/$70.99 or 180/$199.95

ClonazePAM ODT 1MG Dispersible Tablets (PAR): 60/$79.99 or 180/$215.97

ClonazePAM ODT 2MG Dispersible Tablets (PAR): 60/$105.99 or 180/$309.97

KlonoPIN 0.5MG Tablets (GENENTECH): 30/$57.99 or 90/$159.97

KlonoPIN 1MG Tablets (GENENTECH): 30/$63.99 or 90/$185.97

KlonoPIN 2MG Tablets (GENENTECH): 30/$89.99 or 90/$257.98

Disclaimer

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. and Drugs.com represent that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. and Drugs.com make no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. and Drugs.com do not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS Drug Information. © Copyright, 1959-2011, Selected Revisions October 27, 2011. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

† Use is not currently included in the labeling approved by the US Food and Drug Administration.

References

Only references cited for selected revisions after 1984 are available electronically.

1. Roche Laboratories Inc. Klonopin (clonazepam) tablets prescribing information. Nutley, NJ; 1997 Oct.

2. American Psychiatric Association. Diagnostic and statistical manual of mental disorders: DSM-IV™. 4th ed. Washington, DC: American Psychiatric Association; 1994:393-444.

3. Rosenbaum JF, Moroz G, Bowden CL for the Clonazepam Panic Disorder Dose-Response Group. Clonazepam in the treatment of panic disorder with or without agoraphobia: a dose-response study of efficacy, safety, and discontinuance. J Clin Psychopharmacol. 1997; 17:390-400. [IDIS 393807] [PubMed 9315990]

4. Moroz G, Rosenbaum JF. Clonazepam efficacy in the treatment of panic disorder: results of a multicenter placebo-controlled trial. Data on file. Hoffmann-La Roche Inc., Nutley, NJ.

5. Oehrberg S, Christiansen PE, Behnke K et al. Paroxetine in the treatment of panic disorder: a randomised, double-blind, placebo-controlled study. Br J Psychiatry. 1995; 167:374-9. [IDIS 355124] [PubMed 7496647]

6. Westenberg HG. Developments in the drug treatment of panic disorder: what is the place of the selective serotonin reuptake inhibitors? J Affect Dis. 1996; 40:85-93.

7. deh Boer JA. Pharmacotherapy of panic disorder: differential efficacy from a clinical standpoint. J Clin Psychiatry. 1998; 59:30-6; discussion 37-8.

8. Treatment of panic disorder. NIH Consensus Statement Online 1991 Sep 25-27; 9(2):1-24.

9. Reviewers’ comments (personal observations) on sertraline hydrochloride 28:16.04.

10. Davidson JR. The long-term treatment of panic disorder. J Clin Psychiatry. 1998; 59(Suppl. 8):17-23. [IDIS 408262] [PubMed 9707158]

11. Baldwin DS, Birtwistle J. The side effect burden associated with drug treatment of panic disorder. J Clin Psychiatry. 1998; 59(Suppl. 8):39-46. [IDIS 408265] [PubMed 9707161]

12. Gorman JM. The use of newer antidepressants for panic disorder. J Clin Psychiatry. 1997; 58(Suppl. 14):54-9. [IDIS 398618] [PubMed 9418747]

13. Sheehan DV, Harnett-Sheehan K. The role of SSRIs in panic disorder. J Clin Psychiatry. 1996; 57(Suppl. 10):51-60. [IDIS 377784] [PubMed 8917132]

14. Lecrubier Y, Bakker A, Dunbar G et al. A comparison of paroxetine, clomipramine and placebo in the treatment of panic disorder: Collaborative Paroxetine Panic Study Investigators. Acta Psychiatr Scand. 1997; 95:145-52. [PubMed 9065680]

15. Worthington JJ III, Pollack MH, Otto MW et al. Long-term experience with clonazepam in patients with a primary diagnosis of panic disorder. Psychopharmacol Bull. 1998; 34:199-205. [PubMed 9641001]

16. Sheehan DV. Benzodiazepines in panic disorder and agoraphobia. J Affect Disord. 1987; 13:169-81. [PubMed 2890678]

17. Nagy LM, Krystal JH, Woods SW et al. Clinical and medication outcome after short-term alprazolam and behavioral group treatment of panic disorder. Arch Gen Psychiatry. 1989; 46:993-9. [IDIS 260713] [PubMed 2818144]

18. Davidson JR. Use of benzodiazepines in panic disorder. J Clin Psychiatry. 1997; 58(Suppl. 2):26-31. [IDIS 383686] [PubMed 9078991]

19. Lecrubier Y, Judge R for Collaborative Paroxetine Panic Study Investigators. Long-term evaluation of paroxetine, clomipramine and placebo in panic disorder. Acta Psychiatr Scand. 1997; 95:153-60. [PubMed 9065681]

20. Pollack MH, Otto MW, Tesar GE et al. Long-term outcome after acute treatment with alprazolam or clonazepam for panic disorder. J Clin Psychopharmacol. 1993; 13:257-63. [IDIS 317412] [PubMed 8376613]

21. Burrows GD, Judd FK, Norman TR. Long-term drug treatment of panic disorder. J Psychiatr Res. 1993; 27(Suppl. 1):111-25. [PubMed 7908330]

22. Kutcher SP, MacKenzie S. Successful clonazepam treatment of adolescents with panic disorder. J Clin Psychopharmacol. 1988; 8:299-301. Letter. [IDIS 245601] [PubMed 3209726]

a. Roche Laboratories Inc. Klonopin (clonazepam) tablets and Klonopin Wafers (clonazepam) orally disintegrating tablets prescribing information. Nutley, NJ; 2001 Jul.

b. AHFS drug information 2003. McEvoy GK, ed. Clonazepam. Bethesda, MD: American Society of Hospital Pharmacists; 2003:2106-9.

c. AHFS drug information 2003. McEvoy GK, ed. Benzodiazepine general statement. Bethesda, MD: American Society of Hospital Pharmacists; 2003:2353-60.

d. AHFS drug information 2003. McEvoy GK, ed. Anticonvulsants general statement. Bethesda, MD: American Society of Hospital Pharmacists; 2003:2097-102.

e. Gunn VL, Nechyba C, eds. The Harriet Lane handbook: a manual for pediatric house officers. 16th ed. Philadelphia, PA: Mosby; 2002:643-4.

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