With two popular depression medications in short supply, mental health experts say prescribing generic replacements or different drugs can lead to relapse and a new set of side effects.

Certain formulations of Wellbutrin (bupropion) and venlafaxine — sold under the brand name Effexor, among others — are not available throughout the country.

It's a "big problem," according to Dr. Pierre Blier, who treats patients at The Royal Ottawa Mental Health Centre and is director of mood disorder research at The Royal's Institute of Mental Health Research.

Because of the shortage he was forced to prescribe a fast-release version of Wellbutrin, which has caused serious side effects in some of his patients

"Often we see a relapse or a return of their symptoms," he said.

'Rebound anxieties'

Over the last few months, Blier has also had to switch patients taking Effexor to a generic brand.

"Sometimes if [the patients] are switched to generic brands, it's as if they weren't taking any active ingredient," he said.

Other patients have described what Blier called discontinuation symptoms, including "rebound anxieties or a sensation like electrical shocks," he said.

Vanier pharmacist Phil Emberley said he's worried because many of his customers take Effexor or Wellbutrin.

The pharmacy he works at, Pharmasave Respect Rx on Selkirk Avenue, has a close working relationship with Recovery Ottawa, an addiction treatment centre.

Dr. Pierre Blier, director of mood disorder research at The Royal's Institute of Mental Health Research, calls the shortages of several antidepressants 'a big problem.' (supplied )

"I see it as being quite problematic because for patients that are stabilized on an anti-depressant, it's very challenging to have to switch them to another medication that isn't as effective or may come with additional side effects they haven't experienced before," Emberley said.

People taking medications for mental illness are especially vulnerable, he argued.

"You don't want to create any more anxiety in the patient," he said.

"There is a certain degree of, for lack of a better word, experimentation, to find the certain drug to treat their anxiety or depression, so you don't want to constantly change this."

Shortages ongoing

Drug shortages are nothing new in Canada. Over the last few years there have been short supplies of blood pressure medications and some anesthetic drugs used during surgery.

Last summer, a critical shortage of EpiPens — which many people with life-threatening allergies depend on to stop an anaphylactic reaction — raised serious concerns.

In Canada it's mandatory for drug manufacturers to report anticipated and actual shortages to a national website Health Canada oversees.

The shortage of various formulations of Wellbutrin — which is primarily used to treat depression but also seasonal affective disorder — has been ongoing since September 2018.

The current shortfall is with Wellbutrin SR, which releases slowly.

According to Arthur Shannon, a spokesperson for Wellbutrin manufacturer Bausch Health, it's due to a shortage of an active ingredient in the drug that's supplied by another company.

Bausch can't say when Wellbutrin SR will be available again, Shannon said.

Sandoz Canada, one of the manufacturers of venlafaxine, said it doubled its sales of the drug last month and it's now completely out of some formulations of venlafaxine and in limited supply of others.