Stiripentol

Stiripentol (marketed as Diacomit by Laboratoires BIOCODEX) is an anticonvulsant drug used in the treatment of epilepsy. It is unrelated to other anticonvulsants and belongs to the group of aromatic allylic alcohols.

Mechanism of action
As with most anticonvulsants, the precise mechanism is unknown. It has been shown to have anticonvulsant effects on its own. It can prevent the reuptake of GABA and inhibit its metabolism.

It also improves the effectiveness of many other anticonvulsants, possibly due to it inhibiting certain enzymes. This slows the drug's metabolism, increasing blood plasma levels.

E.U.

 * December 2001 - Treatment of severe myoclonic epilepsy in infancy (SMEI). EU orphan designation number EU/3/01/071.

Stiripentol has very limited availability.

Indications and usage
It is indicated as an adjunctive therapy with sodium valproate and clobazam for treating severe myoclonic epilepsy in infancy (SMEI, also know as Dravet's syndrome). Children with SMEI develop often intractable seizures during their first year of life and mental retardation follows. Small-scale trials have show remarkably high response rates, with a significant minority of those treated becoming seizure free.

In addition, it may be used to treat refractory childhood epilepsy in conjunction with carbamazepine. It appears to be less effective in adolescents and adults.

Dosing
Stiripentol is available as a gelatine capsule (250mg, 500mg) and as a sachet of powder to make a drinkable suspension (250mg, 500mg).

Initial dose is 50 mg/kg per day. This may be increased up to 100 mg/kg per day, with a maximum of 4g. The dose to be divided into two or three with meals. The does of other anticonvulsants may have to be reduced (possibly up to 50%).

Side effects
Side effects are largely due to the increase in plasma concentrations of other anticonvulsants and can be reduced by lowering the does of those drugs. Nausea and vomiting are particularly noted when used in combination with sodium valproate.

Drug interactions
Stiripentol inhibits several cytochrome P450 isoenzymes and so interacts with many anticonvulsants and other medicines. This is both a strength and weakness. It appears to increase the potency of phenobarbital, primidone, phenytoin, carbamazepine, clobazam and diazepam. For example, blood levels of carbamazepine can be maintained whist reducing the dose by 50%.