Levetiracetam

Anticonvulsant

Levetiracetam (中文: 左乙拉西坦)is an anticonvulsant medication used to treat epilepsy. It is taken either by mouth as an immediate or extended release formulation or by injection into a vein.

Drug Names

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Levetiracetam tablet 500mg	LEVE01	P1S1S3
Levetriacetam infusion 100mg/ml 5 ml	LEVE05	P1S1S3

Mechanism of Action

Anticonvulsant medication. It inhibits presynaptic calcium channels, reducing neurotransmitter release. This is believed to impede impulse conduction across synapses.

Dosage

Monotherapy of focal seizures	By mouth, or by intravenous infusion ADULT and CHILD over 16 years: Initially 250 mg once daily increased after 1-2 weeks to 250 mg twice daily; thereafter Increased according to response in steps of 250 mg twice daily every 2 weeks Max. 1.5 g twice daily
Adjunctive therapy of focal seizures	By mouth CHILD 1-5 months Initially 7 mg/kg once daily, then Increased in steps of up to 7 mg/kg twice daily every 2 weeks Max. per dose 21 mg/kg twice daily CHILD 6 months – 17 years (body-weight up to 50 kg): Initially 10 mg/kg once daily, then Increased in steps of up to 10 mg/kg twice daily every 2 weeks Max. per dose 30 mg/kg twice daily CHILD 12-17 years (body-weight 50 kg and above): Initially 250 mg twice daily, then Increased in steps of 500 mg twice daily every 2-4 weeks Max. per dose 1.5 g twice daily ADULT: Initially 250 mg twice daily, then Increased in steps of 500 mg twice daily increased every 2-4 weeks Max. per dose 1.5 g twice daily By intravenous infusion CHILD 4-17 years (body-weight up to 50 kg): Initially 10 mg.kg once daily, then increased in steps of up to 10 mg/kg twice daily every 2 weeks Max. per dose 30 mg/kg twice daily CHILD 12-17 years (body-weight 50 kg and above): Initially 250 mg twice daily, then Increased in steps of 500 mg twice daily every 2 weeks Max. per dose 1.5 g twice daily ADULT: Initially 250 mg twice daily, then Increased in steps of 500 mg twice daily every 2-4 weeks Max. per dose 1.5 g twice daily
Adjunctive therapy of myoclonic seizures and tonic-clonic seizures	By mouth, or by intravenous infusion CHILD 12-17 years (body-weight up to 50 kg): Initially 10 mg/kg once daily, then Increased in steps of up to 10 mg/kg twice daily every 2 weeks Max. per dose 30 mg/kg twice daily CHILD 12-17 years (body-weight 50 kg or above): Initially 250 mg twice daily, then Increased in steps of 500 mg twice daily every 2 weeks Max. per dose 1.5 g twice daily ADULT: Initially 250 mg twice daily, then Increased in steps of 500 mg twice daily every 2-4 weeks Max. per dose 1.5 g twice daily

A modified-release preparation is available for once-daily dosing as an adjunct in the treatment of focal seizures in patients aged 16 years and over. As with other antiepileptics, withdrawal of levetiracetam therapy or transition to or from another type of antiepileptic therapy should be made gradually to avoid precipitating an increase in the frequency of seizures. It is recommended:

• Those weighing more than 50 kg, the dose reduction of 1 g every 2 to 4 weeks;
• Those weighing less than 50 kg, the dose reduction should not exceed 20 mg/kg every 2 weeks.

Adverse drug reactions associated with the use of levetiracetam include:

Very common (>10% incidence)	Dizziness drowsiness weakness somnolence
Common (1-10% incidence)	Ataxia Gl effects include abdominal pain, anorexia, diarrhoea, dyspepsia, nausea, vomiting Insomnia Irritability tremor
Rare (<0.1% of incidence)	Agrtanulocytosis, causing increased vulmerability to infection. Choreoathetosis Hepatitis, hepatic failure Hyponatraemia Pancreatitis Stevens-Johnson syndrome Toxic epidermal necrosis

In a study, the incidence of decreased bone mineral density of patients on levetiracetam was significantly higher than those for other epileptic medications.

Pharmacokinetics

Oral bioavailability	Levetiracetam is readily absorbed after oral doses.
Onset of action	Peak plasma concentrations occur within 1.3 hours of oral doses and steady state after 2 days.
Metabolism	It is not extensively metabolized in the liver
Elimination half-life	It is excreted almost entirely in urine. The mean elimination half-life is about 7 hours.

Drug Management

Monitoring

• Liver and kidney function tests to monitor side effects
• changes in mood, the development or worsening depression, and/or any thoughts or behaviour of suicide.

Drug interaction

No significant pharmacokinetic interactions were observed between levetiracetam and concomitant medications. However, levetiracetam possibly increases risk of CARBAMAZEPINE toxicity.

Caution

• Avoid abrupt withdrawal (taper off over 2 weeks or longer) unless serious skin reaction occurs
• Use with care in patients with osteoporosis
• Dose adjustments for patients with hepatic impairment and renal impairment

Hepatic impairment

Halve dose in severe hepatic impairment if creatinine clearance less than 60 mL/minute.

Renal impairment

• Maximum 2 g daily if creatinine clearance 50 - 80 mL/minute.
• Maximum 1.5 g daily if creatinine clearance 30 – 49 mL/minute.
• Maximum 1 g if creatinine clearance less than 30 mL/minute
• Patients receiving dialysis may be given a loading dose of 750 mg when starting levetiracetam followed by doses of 0.5 to 1 g once daily; a supplemental dose of 250 to 500 mg is recommended after dialysis

Pregnancy

Women of child-bearing potential should discuss with a specialist the impact of both epilepsy, and its treatment, on the outcome of pregnancy. There is an increased risk of teratogenicity associated with the use of antiepileptic drug (especially if used during the first trimester)

Breast-feeding

Use during breast feeding is not recommended.

Epilepsy and driving

Driving by patients with epilepsy is generally regulated. Also, antiepileptic drugs may produce CNS-related adverse effects, including dizziness and drowsiness, that could impair a patient’s ability to drive a vehicle or operate machinery, particularly during the initial stages of therapy.

FAQ

How should I take the tablet?

You can take levetiracetam with or without food. If you take it twice day, try to space your doses evenly through the day – for example, first thing in the morning and in the evening. Swallow tablet whole with a drink of water. Do not chew them.

What should I avoid while using?

Avoid abruptly discontinue the medication. Avoid alcohol

What happen if I overdose?

Contact your primary care doctor. If emergency situation, call 999

What happen if I miss a dose?

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.