Monthly Case

Cannabis in epilepsy | 5-2017

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A 27-year-old female patient suffers for 12 years from epilepsy with yearly one to two „smaller“ seizures with impaired consciousnes for 30-40 sec. (complex partial seizures) and former „bigger“ seizures with loss of consciousness (generalized tonic clonic seizures). The cause of epilepsy is unknown, thus we made the diagnosis of cryptogenic focal epilepsy. The patient is administered two anticonvulsants, levetiracetam at 2,000 mg and oxcarbazepine at 1,200 mg daily. Except some slight tiredness and subjective concentration deficits, the combination therapy is well tolerated.

For some years, the patient asks if her epilepsy can also be treated with cannabis, she had read about that in the newspapers. Indeed, since spring 2017 in Germany cannabis can be prescribed for multiple chronic disorders, if other treatments were unsuccessful and if the treating physicians thinks that cannabis is a reasonable next treatment option. The insurance companies are compelled to pay for cannabis treatment.

The problem is that we currently do not have evidence that cannabis works in epilepsy. So far, the derivate cannabidiol has mostly been administered to patients (children and adolescents) with severe, special forms of epilepsy. A clinical trial from the US on 200 mostly young patients has demonstrated that cannabidiol reduces seizure frequency by one third.

This study had two flaws. At first, there was no blinded control group receiving placebo (in intractable epilepsies, the placebo effect results in reduction in seizure frequency in the first months in 15-20% of cases). Second, 50% of patients were co-administered clobazam and 30% valproic acid. In both substances, cannabidiol results in a significant increase in serum concentration. Thus, one can not rule out that reduction of seizure frequency with cannabidiol is mainly explained by placebo effect and/or a pharmacokinetic effect.

Against this background, we currently do not recommend treatment with cannabidiol in epilepsy. We also refer to the critical comment by the Germany Society for Epileptology (in German).

Currently, in the US and probably soon in Germany placebo-controlled, double-blinded clincial trials on cannabidiol in epilepsy will be performed. If proven efficacious, cannabidiol – as a number of other anticonvulsant drugs – may be recommended to our patient.

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