Shankhapushpi Phenytoin

Two patients stabilized on a phenytoin regimen suffered a loss of seizure control after taking shankhapushpi, an Ayurvedic antiepileptic medicine, three times a day. There was also a significant decrease in serum phenytoin concentration from 9.6 to 5.1mg/L. To investigate the possible mechanisms, multiple doses of shankhapushpi were administered to rats and resulted in decreased plasma phenytoin concentrations, whereas single-dose administration was reported to interfere with the antiplatelet effect of phenytoin, thereby implying both a pharmacokinetic and pharmacodynamic basis for the interaction (73). 

Dandekar UP, Chandra RS, Dalvi SS, et al. Analysis of clinically important interaction between phenytoin and shankhapushpi, an ayurvedic preparation. J Ethnopharmacol 1992 35 285-288. 

Decreased concentrations of phenytoin is seen when it is combined with the Ayurvedic syrup shankhapushpi. 

Dandekar, U., Chandra, R., Dalvi, S., Joshi, M., Gokhale, P., Sharma, A., Shah, P., and Kshirsagar, N. 1992. Analysis of a clinically important interaction between phenytoin and Shankhapushpi, an Ayurvedic preparation. J. Ethnopharmacol. 35, 285-288. 

Multiple coadministered doses (but not single doses) decreased plasma phenytoin concentrations single doses decreased the antiepileptic effect of phenytoin Shankhapushpi is used to treat seizures... 

A case report, and an animal study, indicate that an antiepileptic Ayurvedic herbal preparation, Shankhapushpi (SRC), can markedly reduce plasma phenytoin levels, leading to an increased seizure frequency. 

An epileptic man taking phenobarbital 120 mg daily and phenytoin 500 mg daily developed an increase in seizure frequency when Shankhapushpi (SRC) three times a day was given. His plasma phenytoin levels were found to have fallen from 18.2 to 9.3 micrograms/mL, whereas his phenobarbital levels were little changed. When the SRC was stopped the phenytoin plasma levels rose to 30.3 micrograms/mL, and toxicity was seen. A reduction in the dose of phenytoin to 400 mg daily resulted in levels of 16.2 micrograms/mL. Another possible case has also been reported. ... 

Information about this interaction appears to be limited to these reports. Shankhapushpi (SRC) is given because it has some antiepileptic activity (demonstrated in animal studies ), but there is little point in combining it with phenytoin if the outcome is a fall in plasma phenytoin levels, accompanied by an increase in seizure frequency. For this reason concurrent use should be avoided. SRC is a syrup prepared from Convolvuluspluricaulis leaves, Nardostachysjatamansi rhizomes, Onosma bracteatum leaves and flowers and the whole plant of Centella asiatica, Nepeta hindostana and Nepeta elliptica The first two of these plants appear to contain compounds with antiepileptic activity. ... 

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