Clonazepam

Introduction

Clonazepam is a long-acting benzodiazepine with marked antiepileptic properties. It is used to prevent and treat seizures, panic disorder, and the movement disorder known as akathisia. It is taken by mouth. Effects begin within one hour and last between 6 and 12 hours.

Pronunciation

Clopidogrel 75mg

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Clonazepam Tablet 0.5 mg	CLON01	DDA
Clonazepam Tablet 2 mg	CLON02	DDA

Mechanism of Action

• Clonazepam is a benzodiazepine.
• Gama-Aminobutyric acid (GABA) is an inhibitory neurotransmitter, acting on the GABA receptors in the central nervous system (CNS), thus inhibiting the nerve impulses.
• It acts on the benzodiazepine receptors in the brain and the spinal cord. Benzodiazepine receptors in the CNS are linked with GABA receptors as a complex.
• Clonazepam by binding to the benzodiazepine receptors results in activation of the GABA-benzodiazepine receptor complex, resulting in inhibition of nerve impulses, overall depression of brain and spinal cord.
• Thus Clonazepam use helps to promote muscle relaxation, reduce anxiety, control of convulsions and promote sleep.

Dosage

Epilepsy and myoclonus

By mouth ADULT: Initially 1 mg at night for 4 nights, Dose to be increased over 2 to 4 weeks usual dose 4 to 8 mg daily, adjusted according to response ELDERLY: initially 500 micrograms at night for 4 nights dose to be increased over 2 – 4 weeks, usual dose 4 – 8 mg daily, adjusted according to response ADMINISTRATION IN CHILDREN The following usual maintenance doses according to age: 1 to 5 years: 1 to 3 mg daily in 3 divided doses 5 to 12 years: 3 to 6 mg daily in 3 divided doses Older children may be given the usual adult dose

Side Effects

Sedative drugs, including alprazolam, have been associated with an increased risk of death.

Possible side effects include:

Very common (>10% of incidence) or Common (1-10% of incidence)	Amnesia and concentration problems Ataxia (especially in the elderly) Confusion (especially in the elderly) Drowsiness Dizziness Muscle weakness
Infrequent (0.1 -1% of incidence)	Dysarthria Increased frequency of seizures Personality changes Behavioral disturbances
Rare (<0.1% of incidence)	Dysarthria Blood disorders Jaundice Respiratory depression hypersensitivity reactions paradoxical reactions suicidal ideation visual disturbances on long-term treatment

Overdosage can produce CNS depression and coma.

Paradoxical reactions

Although unusual, the following paradoxical reactions have been shown to occur:

• aggression
• mania, agitation, and restlessness
• rage
• twitches and tremor

Pharmacokinetics

Oral bioavailability	Clonazepam is well absorbed after oral doses.
Onset of action	Peak plasma concentrations occur between 1 and 4 hours of a dose.
Metabolism	Clonazepam is metabolized in the liver
Elimination half-life	Clonazepam is eliminated in the urine. Its elimination half-life ranges from about 20 to 40 hours, and occasionally more.