May cause weed attacks

Does cannabis work reliably against epilepsy?

MANNHEIM. Examples like that of little Charlotte Figgs give hope to critically ill epilepsy patients: the girl developed her first seizures at the age of three months, and by the age of three she suffered up to 300 grand mal seizures per week, reports the news channel CNN.

The doctors diagnosed Dravet syndrome. No therapy helped, brain development came to a standstill, and the girl was on the verge of death. In desperation, the parents tried a cannabis oil with little psychoactive THC but a lot of cannabidiol.

For the first time, the child stayed seizure-free for over a week. Charlotte can now lead an almost normal life with one or two mostly nocturnal seizures a month.

Both pro- and anticonvulsant effects

No wonder some epilepsy forums are promoting cannabis as a natural anticonvulsant. At the DGN congress in Mannheim, however, Professor Heidrun Potschka warned against the uncontrolled intake of phytocannabinoids: These have both pro- and anticonvulsive effects.

There are reports of epilepsy sufferers who repeatedly suffered seizures after jointing. Cannabis is more of a double-edged sword, explained the pharmacologist from the LMU Munich.

After all, the function of the cannabinoid receptors in the brain has been well studied. The presynaptic CB1 receptor slows down overactive synapses via a feedback loop: If too much transmitter is released, the postsynaptic releases endocannabinoids that dock on the CB1 receptor. This then throttles the transmitter production.

However, this happens with both excitatory and inhibitory connections. Whether a joint with the intoxicating CB1 agonist THC has a pro-convulsive or anti-convulsive effect depends on the current status of the brain, said Potschka.

Can cannabinoids reduce seizures quickly?

After all, cannabinoids could end seizures faster. This has been confirmed in animal models and the mechanism is also plausible: the active ingredients switch off overactive synapses during an attack.

This could possibly explain the effects in Dravet's syndrome, which also makes cannabinoids interesting for the treatment of status epilepticus.

However, cannabidiol (CBD) is therapeutically more important than the intoxicating THC. This substance does not make you feel elated and does not only work through the CB1 receptor. However, according to Potschka, little is known about the exact mode of action of CBD.

Researchers were able to demonstrate a certain anticonvulsant effect in animal models. The active ingredient is currently being clinically tested for Dravet and Lennox-Gastaut syndromes.

"More like the principle of hope"

In a study with 162 refractory epilepsy patients, the frequency of seizures was reduced by 37% using CBD. However, the examination was not blinded, which greatly limits its informative value, according to Potschka.

It should also be noted that there is a high potential for interaction: CBD inhibits various cytochrome P450 enzymes, especially CYP2C and CYP3A. As a result, increased serum levels and side effects are observed with clobazam treatment.

The pharmacologist suspects that some of the described successes with CBD are ultimately based on increased clobazam levels. "So one cannot speak of a rational therapy with cannabinoids, but rather of the principle of hope," she said.