In this article, we will discuss Anticonvulsants-Dosage (Part-VII). So, let’s get started.
Valproate sodium Initial dose 10-15 mg/kg/day q 8-12 hr oral, can increase up to maximum of 60 mg/kg/day (increments of 5-10 mg/kg/day at weekly intervals). Therapeutic level 50-100 mg/L. In status epilepticus, 20 mg/kg loading dose followed by 5-10 mg/kg dose q 8 hr. Infuse over one hour up to a maximum of 20 mg/min.
Adult dose: 600 mg daily in 2 divided doses, increase by 200 mg at weekly intervals. The usual adult dose is 1-2 g daily up to a maximum of 5 g.
Indication: Broad spectrum for majority of epilepsies, e.g.generalized tonic-clonic partial seizures, absence attacks, myoclonic, atonic, frequent febrile seizures, Lennox-Gastaut syndrome, West syndrome and juvenile myoclonic epilepsy.
C/I: Active liver disease, urea cycle disorders.
Side Effects: Hepatic and renal dysfunction, “Reye-like” syndrome,
bleeding, alopecia, excessive weight gain, aggravation of polycystic ovarian disease, and false positive urine sugar test.
(Encorate chrono, epilex chrono, manoval, magprol CR, torvate chrono tab 200 mg; valparin chrono, cinaval chrono tabs 200 mg, 300 mg, 400 mg, 500 mg; valprol CR 200 mg, 300 mg, 500 mg; syrup valparin, epilex 200 mg per 5 ml; injection encorate 100 mg/ml for IV infusion as 5 ml vial).
Vigabatrin It is a structural analogue of gamma-aminobutyric acid (GABA) which irreversibly inhibits the enzyme GABA transaminase. Initial dose 50-150 mg/kg/day. The dose is gradually increased by 30 mg/kg every 5 days. Stop if there is no response in 2 weeks.
Adult dose: 10 g daily q 12 hr. Increase gradually at weekly interval up to 3.0 g per day q 12 hr.
Indication: Add-on drug for resistant partial seizures, infantile spasms especially due to tuberous sclerosis and Lennox-Gastaut syndrome. It can be combined with valproate and IVIG. May be used as a first-line drug for infantile spasms along with steroids.
Side Effects: Weight gain, hyperkinesia, visual field defects and retinopathy
(Sabril and vegarin tab 500 mg).
Zonisamide 4-8 mg/kg/day q 12 hr. Avoid below 16 years.
Adult dose: 50 mg daily q 12 hr. Increase by 50 mg/day at weekly intervals. Usual dose is 200-600 mg/day q 12 hr.
Indication: Add-on therapy for partial and tonic-clonic seizures, atypical absences, Lennox-Gastaut syndrome and juvenile myodonic epilepsy.
(Zonisep caps 25 mg, 50 mg; zonegram tabs 25 mg, 100 mg; zonit, zonimid, zonicare tabs 50 mg, 100 mg)