Continued...

New Derivatives or formulations of First line ASDs

Zonisamide: It was recently approved in US for adjunctive treatment of partial seizures although it has been used in Japan for more than a decade now. Chemically it is a sulphonamide. It inhibits a particular voltage activated calcium channel known as T current. It also inhibits sodium channel. It is well absorbed and metabolized by acetylation and glucuronidation. Zonisamide extensively binds to erythrocytes, resulting in an eight-fold higher concentration of zonisamide in red blood cells (RBC) than in plasma. Zonisamide is easy to titrate and has a short latency of onset, thereby making it an attractive therapeutic alternative. It is excreted through kidneys. Its important adverse effect is development of renal calculi (19). But various studies in Japan have confirmed its efficacy and safety (20). It has been found efficacious in refractory partial epilepsy (21).

Table 2: Clinical Uses of Second Generation Anti-seizure drugs in Pediatric Practice

Drug	Acts on	Indications	Dose
Felbamate	NMDA & GABA	Adjunctive therapy for partial seizures with or without generalization. Adjunctive therapy for partial and generalized seizures associated with Lennox-Gastaut syndrome	Start with 15mg/mg/day and increase up to 45mg/kg/day or seizure control is achieved
Gabapentin	GABA	Adjunctive treatment of partial seizures with or without generalization in patients older than 12 years	25-40 mg/kg/day and given in divided doses (three times a day).
Lamotrigine	Sodium Channel	Partial epilepsy, Add-on treatment of generalized seizures in Lennox-Gastaut syndrome, Childhood and Juvenile absence, Juvenile myoclonic epilepsy	Start with 0.3mg/kg/day. Increase 0.3 mg/kg weekly to up to 4.5-7 mg/kg/day or seizure control is achieved
Topiramate	Sodium Channel	Adjunctive therapy for partial and generalized seizures in adult and pediatric patients older than 2 years of age. Adjunctive therapy for Lennox-Gastaut syndrome and infantile spasms, Juvenile myoclonic epilepsy	Start with 1-3 mg/kg/day and increase 1-3 mg/kg weekly up to 5-9 mg/kg/day in two divided doses or seizure control is achieved
Tiagabine	GAT1/GABA	Refractory partial epilepsy in children above 12 years of age	Start with 4 mg daily and increase 4 mg weekly to reach a maximum dose of 32 mg daily or seizure control is achieved
Levetiracetam	Not Known	Partial seizures with or without generalization. Adjunctive therapy for Juvenile myoclonic epilepsy	Start with 20 mg/kg in two divided doses and increase 20 mg/kg every 2 weekly up to 60 mg/kg/day or seizure control is achieved
Vigabatrin	GABA	Refractory partial seizures, Infantile spasms	40 mg/kg/day, increasing to 80 to 100 mg/kg/day or seizure control is achieved
Zonisamide	Ca2+ (T Current)	Adjunctive treatment of partial seizures in patients older than 16 years	Start with 100 mg/day and increase 100 mg every 2 weeks up to 400 mg/day or seizure control is achieved