A case report, and an animal study, indicate that an antiepileptic Ayurvedic herbal preparation, SRC (Shankhapushpi), can markedly reduce
serum phenytoin levels, leading to an increased seizure frequency if the
phenytoin dosage is not raised. SRC is a syrup prepared from Convolvulus pluricaulis leaves, Nardostachys jatamansi rhizomes, Onosma bracteatum leaves and flowers, and the whole plant of Centella asiatica, Nepeta hindostana and Nepeta elliptica.
Shankhapushpi (SRC) is given because it has some antiepileptic activity but there is little point in combining it with
phenytoin if the outcome is a fall in
serum phenytoin levels, accompanied by an increase in seizure frequency. For this reason concurrent use should be avoided. It would seem prudent to be similarly cautious with the use of fosphenytoin, a prodrug of
phenytoin.