Summary Safety Review - Strontium - Risk of Heart and Circulatory Side Effects

October 22, 2015

Product

Oral natural health products containing strontium

Potential Safety Issue

Serious heart and circulatory side effects

Key Messages

  • Strontium is a naturally occurring mineral available as an ingredient in over-the-counter (OTC) natural health products. It is sold in various salt forms and can be used to help support bone health.
  • As a result of a European Medicines Agency's safety review (EMA) on the prescription dose of the ranelate form of strontium (strontium ranelate), Health Canada conducted a review of strontium. The EMA safety review found that the dose of 680 mg per day was beneficial for severe osteoporosis, but that it should not be used in patients who have pre-existing heart or circulatory problems.
  • Health Canada's review did not find information available on cardiovascular risk with the strontium ranelate form at doses less than 680 mg strontium per day, or with other non-ranelate forms of strontium at any dose. While uncertainties remain, Health Canada is taking a precautionary approach and recommending updates to the labels of products containing strontium, including informing consumers not to use these products if they have pre-existing heart or circulatory problems, such as heart attack, stroke or blood clot.

Overview

The European Medicines Agency completed a safety review of strontium ranelate, a drug available by prescription only in Europe at a dose of 680 mg per day and used to treat osteoporosis that is considered severe due to the high risk of fracture. Analysis demonstrated that the increased risk of heart and circulatory effects was only significant in patients with a current or past history of heart and circulatory problems. Health Canada started its safety review because the risk of heart and circulatory side effects is a serious health issue, and because strontium is found in licensed natural health products as strontium salts, including strontium citrate, strontium lactate, and strontium gluconate.

Use in Canada

  • In Canada, strontium is a mineral and classified as a natural health product ingredient. It is found in licensed natural health products in various salt forms, including strontium citrate, strontium lactate, and strontium gluconate.
  • At the time of the review, Health Canada had licensed 30 natural health products containing strontium (included in oral multi-ingredient products and in toothpastes). Of these, 16 provided daily doses of elemental strontium ranging from 4 mg up to 682 mg, in the forms of strontium citrate, strontium lactate, or strontium gluconate.

Safety Review Findings

  • There were no CanadianFootnote a or international reports of heart or circulatory side effects associated with the strontium salt forms licensed in Canada, including strontium citrate, strontium lactate, and strontium gluconate, at the time of the review.
  • Health Canada's review determined that strontium is the only component of strontium salt combinations that plays an active role in the body, while the salt parts like ranelate, lactate, citrate, and gluconate help with absorption of the strontium. There is not enough information available to compare how the different strontium salt combinations are absorbed in the body or the safety risk of heart or circulatory side effects with low dose strontium.
  • Health Canada's review did not find information available on cardiovascular risk with the strontium ranelate form at doses less than 680 mg/ day, or with other non-ranelate forms of strontium at any dose. While uncertainties remain, Health Canada is taking a precautionary approach and considers that strontium, regardless of the form it comes in, may have a potential risk of cardiovascular side effects in people who are already at risk.

Conclusions and Actions

  • Although available evidence for heart and circulatory side effects involved strontium ranelate taken at 680 mg per day only, a risk at lower doses of strontium ranelate and with other strontium salt combinations could not be ruled out.
  • While uncertainties remain, Health Canada is taking a precautionary approach and recommending that licence holders of those products providing adults with more than 4 mg of elemental strontium per day update the labelling to inform consumers not to use these products if they have, or are at high risk for heart disease, circulatory problems, or blood clots.
  • Health Canada has issued an Information Update to inform Canadians about the label revisions and potential risk of cardiovascular side effects.
  • Health Canada will continue to monitor safety information involving all salt forms of strontium, as it does for all health products on the Canadian market, and will take additional actions, if warranted.

Additional Information

The analysis that contributed to this safety review included scientific and medical literature, Canadian and international reports of side effects, and what is known about the use of this strontium both in Canada and internationally.

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