Elmiron, a medication prescribed for bladder issues that has been linked to a unique form of macular degeneration causing vision loss, continues to rank among the top publicly funded non-patented drugs in Canada, according to a government report on public drug plan expenditures published earlier this year.
The latest edition of Canada's "Annual Public Drug Plan Expenditure Report"1 covering 2020/21 ranked Elmiron among the top single-source non-patented medicines in Canada by drug cost.
The popularity of the drug has held year-over-year as compared to 2019/20, despite the drug having been the subject of a Health Canada advisory in December 2020 due to cases of a novel eye disease being reported in patients, which can result in permanent harm to vision.
Elmiron is a drug prescribed for a chronic bladder condition: interstitial cystitis
Elmiron (pentosan polysulfate sodium) was first marketed in Canada beginning in the 1990s as a form of initial and maintenance treatment for interstitial cystitis.
Interstitial cystitis is a chronic condition that causes pressure and severe pain in the bladder, which affects hundreds of thousands of Canadians, predominantly women. Elmiron, whose active ingredient is "pentosan polysulfate sodium" aka "pentosan polysulfate," is an oral medication specifically approved to treat this condition. Generic versions are not available.
For many years while the drug was available in Canada, the product monograph contained no warnings or precautions regarding any risk of potential vision issues associated with the drug.
Health Canada warned doctors of the link between Elmiron and a unique eye disease
In September 2019, more than two decades after the drug first entered the Canadian market, the manufacturer Janssen Inc. changed the drug's product monograph to add a warning section about cases of a unique form of maculopathy (i.e., macular degeneration) being reported in patients.
In October 2020, Janssen updated the drug's monograph again to add a "black box" warning – the most serious type of pharmaceutical warning – to notify patients about the unique eye disease "pigmentary maculopathy" and to encourage users to get regular retinal exams for early detection.
Health Canada subsequently published an advisory for doctors in December 2020, notifying them that Elmiron was linked to cases of pigmentary maculopathy and that the disease may result in a permanent decrease or loss of central vision. The "Health Professional Risk Communication" added that the drug was now contraindicated in patients with any history of macular pathology and urged doctors to counsel patients to report any changes in their vision.
Despite the vision risks, Elmiron remains among the top publicly funded drugs in Canada
In spite of the Health Canada advisory and new "black box warning" for Elmiron which both came in 2020, Elmiron still ranked among the most popular single-source non-patented medicines in Canada by drug cost for the 2020/21 reporting period according to the latest CompassRx: Annual Public Drug Plan Expenditure Report.
The 8th edition of CompassRx, published in January 2023, notes that the public drug plans across Canada's provinces and territories spent over $3.6 million in public funds to subsidize Elmiron prescriptions for Canadians in 2020/21.
CompassRx: is an annual Patented Medicine Prices Review Board (PMPRB) publication that explores trends in prescription drug expenditures in Canadian public drug plans. The PMPRB is a federal regulatory and reporting agency, whose mandate includes reporting on pharmaceutical trends of medicines, including those involving single-source non-patented medicines.
Single-source non-patented medicines are brand-name drugs for which a patent has expired but generic alternatives have not entered the market to compete for sales. Elmiron – the only approved medicine in Canada with pentosan polysulfate as its active ingredient – has placed among the top non-patented single-source drugs in Canada for many years. Elmiron's 22nd ranking among non-patented single-source drugs in 2020/21 was near identical to its rankings in 2019/202 (21st), 2018/193 (21st), and 2017/184 (22nd).
The continued widespread prescribing of Elmiron documented in the current CompassRx report is notable as it occurred despite the 2020 communications to doctors and patients about the risks of vision harms linked to the drug. Given the continued popularity of Elmiron, it's possible that the warnings about vision loss may not effectively reach patients and doctors, and many Canadians may continue to use Elmiron unaware of the potential risk of permanent harm to their eyes.
Footnotes
4. http://www.pmprb-cepmb.gc.ca/view.asp?ccid=1474⟨=en
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