Published 24 September 2009, doi:10.1136/bmj.b3751
Cite this as: BMJ 2009;339:b3751

Practice

Drug point

Chitosan may decrease serum valproate and increase the risk of seizure reappearance

Pasquale Striano, consultant1, Federico Zara, consultant1, Carlo Minetti, professor of paediatric sciences1, Salvatore Striano, professor of neurology2

1 Unit of Muscular and Neurodegenerative Diseases, "G Gaslini" Institute, University of Genova, Genova, 2 Epilepsy Center, Department of Neurological Sciences, Federico II University, Napoli, Italy

Correspondence to: Dr Pasquale Striano, Unit of Muscular and Neurodegenerative Diseases, "G Gaslini" Institute, Largo Gaslini 5, 16147-Genova, Italy pstriano@email.it

The first 150 words of the full text of this article appear below.

We report two cases of probable interaction between the commonly used anticonvulsant valproate and chitosan, a substance available worldwide to help weight loss.

A 35 year old woman with idiopathic generalised epilepsy, who had not had seizures for three years while taking valproate (500 mg twice/day; 52 µg/ml) and phenobarbital (75 mg/day), had the sudden reappearance of myoclonic jerks, absences, and a tonic-clonic seizure a few days after a dietary supplementation with chitosan (500 mg twice/day) for weight loss. She denied changing her diet and consuming other drugs or natural substances. Seizures remitted after chitosan was stopped. Three months later she restarted chitosan and within five days she had daily absences, myoclonus, and generalised abnormalities on electroencephalogram. Serum concentrations of valproate were undetectable despite regular intake of the drug, whereas phenobarbital remained at therapeutic concentration (20 µg/ml). Chitosan was discontinued. Seizures remitted and valproate concentration returned to baseline levels (50 . . . [Full text of this article]


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