Sodium Valproate

Sodium valproate(中文: 丙戊酸鈉) or valproic acid is an anticonvulsant medication used primarily in the treatment of epilepsy. It has been used both alone and as an add-on therapy for absence seizures, partial seizures, and generalized tonic-clonic seizures. It's also used to prevent migraine headaches and help with manic episodes in bipolar disorder.

Drug Names

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Sodium valproate Solution	VALP03	P1S1S3
Enteric-coated tablet	VALP02	P1S1S3
CR tablet 200 mg	VALP06	P1S1S3
CR tablet 300 mg	VALP07	P1S1S3
CR tablet 500 mg	VALP05	P1S1S3

Mechanism of Action

Anticonvulsant medication. It blocks voltage-gated sodium channels and increased brain levels of gamma-aminobutyric acid.

Dosage

1. Epilepsy

Oral: Initially 600 mg daily in 1-2 divided doses increase in steps of 150 -300 mg every 3 days maintenance 1-2g daily, maximum 2.5g daily

Administration in child:

Child 1 month-11 years: initially 10-15 mg/kg daily in 1-2 divided doses, (max per dose 600mg.) maintenance 25-30mg/kg daily in 2 divided doses, doses up to 60mg/kg daily may be used. Monitor hematological parameters if dose exceed 40mg/kg

Child 12-17 years: initially 600 mg daily in 1-2 divided doses increase in steps of 150 -300 mg every 3 days maintenance 1-2g daily, maximum 2.5g daily

2. Migraine prophylaxis:

Oral: initially 200mg twice daily, increased if needed to 1.2-2.5g daily in divided dose.

3. Mania

Initially 750mg daily in 1-2 divided doses, usually dose 1-2g daily in 1-2 divided doses. Carefully monitor if dose exceed 45mg/kg

Side Effects

Common side effects include: Aggression behaviour, anaemia, confusion, convulsion, deafness, diarrhoea, extrapyramidal disorder, gastric irritation, haemorrhage, headache,hyponatremia , memory impairment, menstrual disturbance, nausea, nystagmus, sedation, stupor, thrombocytopenia, transient hair loss, tremor, weight gain.

More serious side effect include:

• Acute hepatic failure.
• Acute pancreatitis.

Discontinue immediately if persistent vomiting and abdominal pain, anorexia, jaundice, oedema, malaise, or loss of seizures control.

Pharmacokinetics

Oral bioavailability	Sodium valproate is rapidly absorbed from the gastrointestinal tract
Onset of action	Peak concentrations being attained 1 to 2 hours after administration
Metabolism	Peak concentrations being attained 1 to 2 hours after administration
Elimination half-life	Elimination half-life approximately 9-16 hours

Drug Management

Monitoring:

• Monitor liver function before therapy and during the first 6 month of treatment, espesically patient with risk.
• Measure full blood count including platelet to make sure no potential bleeding risk.

Drug interaction:

Drugs given with sodium valproate	Potential Effect
Aspirin	Enhance sodium valproate effect
Antibiotics: Erythromycin Carbapenems	May increase plasma valproate concentration.
Antidepressant	Combine may cause lower seizure threshold.
Anticoagulants: coumarins (warfarin)	Sodium valproate possibly increase the anticoagulant function of warfarin.
Other anticonvulsant	Carbamazepine reduces the plasma concentration of sodium valproate, also the plasma concentration of the active metabolite of carbamazepine increased. Sodium valproate increases other anti-epileptic plasma concentration.
Anxiolytics: Clonazepam midazolam	Carbamazepine reduces their plasma concentration
Antipsychotics Clozapine Olanzapine	Increase or decreased clozapine plasma concentration Increase the risk of side effect including neutropinea when combining with olanzapine
Oestrogens	Reduced plasma valproate concentration
Bupropion	Inhibit the metabolism of Bupropion (increase plasma concentration)

Caution

• Systemic lupus erythematosus

Contraindications

• Severe hepatic dysfunction (family history or personal)
• Known mitochondrial disorder.
• Acute porphyria

Hepatic impairment Avoid if possible

Renal impairment Reduce dose

Pregnancy sodium valproate is associated with congenital malformation and neurodevelopmental effects, avoid unless there was no other safer alternative.

Breast-feeding Use during breast feeding is not recommended.

Warning:

1. This medicine may make you sleepy. If this happens, do not drive, use tools or machines

2. Do not stop taking this medicine unless your doctor tells you to stop

FAQ

How should I take the tablet?

Donepezil tablet and orodispersible tablet should be taken orally at bedtime, or as directed by the doctor. The orodispersible tablet should be placed on the tongue and allowed to disperse before swallowing with or without water. Both formulations can be taken with or without food.

What should I avoid while taking?

Avoid abruptly discontinue the medication.

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.