Clonazepam
Clonazepam(中文:氯硝西泮) 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[edit]
Clonazepam 0.5mg[edit]
Drug Names[edit]
| 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[edit]
- 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[edit]
| Epilepsy and myoclonus | By mouth
ADULT:
ELDERLY:
ADMINISTRATION IN CHILDREN The following usual maintenance doses according to age:
|
|---|
Side Effects[edit]
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) |
|
|---|---|
| Infrequent (0.1 -1% of incidence) |
|
| Rare (<0.1% of incidence) |
|
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[edit]
| 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. |
Drug Management[edit]
Monitoring[edit]
- changes in mood, the development or worsening depression, and/or any thoughts or behaviour of suicide.
- Blood pressure and respiratory rate should be monitored
- An increased risk of falls and fractures in elderly, so fall prevention is needed
- Some patients develop blood dyscrasias, and have raised liver enzymes, so periodic blood counts and liver function tests are recommended
Dependence and Withdrawal[edit]
- One-third of individuals treated with benzodiazepines for longer than 4 weeks develop a dependence on the drug and experience a withdrawal syndrome upon dose reduction.
- Tolerance develops to the anticonvulsant effects of clonazepam.
- Clonazepam should therefore be withdrawn by tapering the dose to minimize occurrence of withdrawal symptoms.
Drug interaction[edit]
- Enhanced sedation effects may occur if clonazepam is given with other drugs that have CNS-depressant properties; these include alcohol, antidepressants, sedative antihistamines, antipsychotics, and opioid analgesics.
- Clonazepam decreases the level of carbamazepine, and likewise, clonazepam’s level is reduced by carbamazepine.
- Clonazepam may affects levels of phenytoin. In turn, phenytoin may lower clonazepam plasma levels by increasing the speed if clonazepam clearance by about 50% and decreasing its half-life by 31%.
- Antifungals, such as ketoconazole, may inhibit the metabolism of clonazepam, and increase its side-effect.
Caution[edit]
- particular care in pregnancy,
- elderly, due to increased susceptibility to side-effects, especially loss of coordination and drowsiness
- people with history of alcohol dependence or abuse
- people with history of drug dependence or abuse
- people with psychiatric disorders
- avoid prolonged use and abrupt withdrawal thereafter
Contra-indications[edit]
Bromazepam is contraindicated in patients with:
- severe hepatic impairment
- sleep apnoea syndrome
- chronic obstructive airways disease (COPD) with incipient respiratory failure
- Myasthenia gravis
- Acute narrow-angle glaucoma
- Chronic schizophrenia
Hepatic impairment[edit]
- Start with smaller initial doses or reduce dose.
- Can precipitate coma.
Renal impairment[edit]
- Start with small doses in severe impairment.
Pregnancy[edit]
Possible adverse effects of use of benzodiazepines such as clonazepam during pregnancy include: miscarriage, malformation, intrauterine growth retardation, and function deficits.
Breast-feeding[edit]
Use during breast feeding is not recommended.
Driving and skilled tasks[edit]
May impair judgment and increase reaction time, and so affect ability to drive or operate machinery. Patients should be warned not to operate dangerous machinery or motor vehicles until it is known that they do not become drowsy from clonazepam therapy.
FAQ[edit]
How should I take the tablet?[edit]
If you get nauseous after taking clonazepam on an empty stomach, try taking it with food.
What should I avoid while taking?[edit]
Do not eat grapefruit or drink grapefruit juice.
Do not drink any alcohol while taking clonazepam.
What happen if I overdose?[edit]
Contact your primary care doctor. If emergency situation, call 999
What happen if I miss a dose?[edit]
Take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
