The Canadian Epilepsy Alliance says an ongoing shortage of an epilepsy medication is leaving some patients worried they鈥檒l start to have seizures again if they switch to an alternative.

The shortage of Teva-clobazam, which began last May, is expected to last until April next year, according to Health Canada鈥檚 drug shortages website.

The alliance represents epilepsy organizations across the country and says patients are scrambling to find doses at different pharmacies.

Another version of the drug, Apo-clobazam, is available but experts say some people can鈥檛 take the medications interchangeably without risking breakthrough seizures.

Dr. Eduard Bercovici, a Toronto neurologist specializing in epilepsy, says drug shortages can be 鈥渄evastating鈥� for people relying on them to prevent seizures.

The reason for the Teva-clobazam shortage is listed as 鈥渄isruption of the manufacture of the drug.鈥�

The manufacturer, Teva Canada, has not responded to an email The Canadian Press sent Wednesday asking for more details.

鈥淥ne of the main issues with epilepsy is that it is an unpredictable, unprovoked condition and someone who is well controlled and is taking their medication on a regular basis is going to find it very nerve-racking 鈥� to know that they may have a seizure with missing medications,鈥� Bercovici said in an interview.

Teva-Clobazam and Apo-Clobazam, manufactured by Apotex, are benzodiazepines that are basically the same, he said.

But for reasons that aren鈥檛 clear, Bercovici said, some people with epilepsy are 鈥渧ery sensitive鈥� and have adverse side effects, including a return of seizures, if they switch between the two versions.

He said that sensitivity can happen with either medication, noting he has many patients who take the Apotex version.

Rev. John Dickinson, a 90-year-old living in Kitchener, Ont., is one of the people who can鈥檛 switch between the two and needs the Teva version, his daughter Rebecca Roland said.

Dickinson is a 鈥渧ery healthy, very active鈥� senior whose only health issue is epilepsy that started after a workplace head injury in the 1980s, said Roland, who also lives in Kitchener.

He was on a brand-name version of clobazam for decades, which controlled his seizures well, she said.

When his drug benefit program told him to switch to a generic version about a decade ago, Dickinson was put on Apo-clobazambut it didn鈥檛 control his seizures during the night, she said.

Within a week, his doctor switched him to Teva-clobazam and he hasn鈥檛 had any issues with seizures since, Roland said.

鈥淚t鈥檚 really been a lifesaver for him,鈥� she said.

But in August, Dickinson鈥檚 pharmacy told them they were out of the drug because of the ongoing shortage.

Since then, Roland and other family members have been calling pharmacies around Ontario and driving hundreds of kilometres 鈥� from St. Catharines to Bracebridge 鈥攖o find whatever doses of Teva-clobazam they can get.

鈥滻f you can find a pharmacy that has it, they only have a little bit,鈥� she said.

When they learned the shortage was going to extend into next April, Dickinson and Roland became worried they wouldn鈥檛 be able to keep finding doses and went to his neurologist.

鈥漌e were really hoping that there would be an alternate solution to the situation,鈥� Roland said.

But there wasn鈥檛 鈥� except to switch him to the Apotex version of clobazam.

鈥淭he neurologist said, 鈥榳ell, switch him to the Apo and then if he has a seizure come and see me,鈥欌�� Roland said.

But she worries that at 90 years of age, switching medications is too high a risk for her father to take.

鈥淗e says, 鈥榃ell If I have to switch, you know, can you phone me every morning just to make sure I wake up?鈥欌�� Roland said.

鈥淚 think that鈥檚 pretty heartbreaking.鈥�

According to the Canadian Epilepsy Alliance, about 260,000 Canadians have epilepsy.

Laura Dickson, president of the alliance, said that switching people off of medications that are working for them during a shortage is 鈥渁 safety issue.鈥�

鈥淧eople that are stabilized on antiseizure medications get their driver鈥檚 licenses back and are able to drive,鈥� said Dickson, who is also executive director of the Epilepsy Association of Calgary.

鈥淭hey also hold jobs where they鈥檙e required to obviously perform on a day-to-day basis 鈥� so when these shortages occur, people can experience breakthrough seizures impacting various aspects of their lives.鈥�