Primidone Nicotinamide

Drugs that may affect primidone include acetazolamide, carbamazepine, hydantoins, isoniazid, nicotinamide, and succinimides. 

Nicotinamide Carbamazepine Primidone Risk of toxicity of the object drugs Inhibition of metabolism of the object drugs... 

Increased effects (P450 3A4 inhibitors) cimetidine, danazol, diltiazem, erythromycin, troleandomycin, clarithromycin, fluoxetine, isoniazid, niacinamide, nicotinamide, propoxyphene, ketoconazole, itraconazole, verapamil,and valproate Decreased effects (P450 3A4 inducers) cisplatin, doxorubicin, felbamate, rifampin, phenobarbital, phenytoin, primidone, theophylline... 

Nicotinamide Deer, metabolism of primidone Corticosteroids Deer, corticosteroids... 

Primidone use Is associated with decreases In CBZ, lamotrigine, valproate, tiagabine, and zonisamide serum levels. Primidone levels are increased by nicotinamide and Isonlazid. Hydantoins increase the plasma concentrations of primidone, phenobarbital, and PEMA. CBZ Increases levels of phenobarbital derived from primidone. Primidone levels are decreased by succinimides, CBZ, and acetazolamide. 

High daily doses of pyridoxine can cause 35% reductions in phenytoin levels and 50% reductions in phenobarbital levels in some patients. Some evidence suggests that high doses of nicotinamide reduce the conversion of primidone to phenobarbital, and increase carbamazepine levels. 

Nicotinamide 41 to 178 mg/kg daily increased the levels of primidone and deereased the levels of primidone-derived phenobarbital in 3 ehil-dren. Although two of the children had refractory seizures, seizure frequency decreased while on nicotinamide. Two of the ehildren on carbamazepine had increases in their carbamazepine levels. ... 

Bourgeois BF, Dodson WE, FerrendeUi JA. Interactions between primidone, carbamazepine, and nicotinamide. Neurology p982) 32,1122-26. 

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