Health Canada and makers of domperidone, approved for use in Canada to treat symptoms caused by some stomach and intestinal problems and some Parkinson's drugs, are advising that the drug has been associated with serious heart problems that could result in death.

The new safety information was posted Wednesday on Health Canada's website by the health products and food branch, which notifies health professionals, consumers and other interested parties about any safety or public health issues.

Breastfeeding mothers have been warned by the FDA against taking domperidone to increase milk production. (IStock)

Domperidone, which goes by a number of names, including domperidome maleate, is manufactured by about a dozen pharmaceutical companies. In Canada, it's approved to treat symptoms of slowed stomach emptying caused by some stomach problems such as gastritis or gastroparesis, and to prevent nausea and vomiting caused by some Parkinson's drug treatments.

Domperidone also has been used by breastfeeding women to increase milk production, but neither Canada nor the U.S. has authorized the drug's use for that purpose.

'Off-label' use of drugs up to individual doctors

Health Canada told CBC News in an email on Thursday that it is aware domperidone has been prescribed to stimulate milk production, and that such "off-label" use "falls within the practice of medicine, which is regulated provincially and territorially by the various professional colleges."

Current domperidone drug labels advise that nursing is not recommended for women taking domperidone unless the expected benefits outweigh any potential risk, the email said.

Health Canada also said it has not received any adverse reaction reports of serious heart-related problems "in relation to the use of domperidone used to stimulate milk production in breastfeeding women."

In 2004, the U.S. Food and Drug Administration warned health-care professionals and breastfeeding women not to use domperidone to increase milk production, saying it is concerned with the potential public health risks associated with using the drug for a purpose not approved in the U.S. or any other country. The FDA said there were reports of cardiac arrhythmias, cardiac arrest and sudden death in patients receiving an IV form of the drug, and that that form was no longer being marketed.

Drug's use to aid breast milk production not authorized

Health Canada's safety notice says the risk of serious abnormal heart rhythms or sudden death from cardiac arrest may be higher in patients taking domperidone at doses greater than 30 milligrams a day, or in patients over age 60, based on results from recent studies in the Netherlands and Saskatchewan.

It recommends that:

• Domperidone be used at the lowest possible dose that is right for you, including if you are suffering from Parkinson's disease.
• If you have a heart with abnormal electrical activity (especially a condition called QT prolongation), a condition such as heart failure or low blood levels of potassium or magnesium, domperidone should be used with caution if it's taken with other drugs that can change the electrical activity of the heart.

Canadians urged to seek medical advice

Changes to the electrical activity of the heart can lead to serious abnormal heart rhythms that can be life-threatening, Health Canada says.

The safety alert urges anyone taking domperidone not to stop taking the drug or change the dose before consulting with their doctors, and to ask their health-care providers if they have been given the correct dose. However, anyone experiencing symptoms of abnormal heart rhythms such as heart palpitations, dizziness, fainting, or seizures should stop taking the medication and seek immediate medical attention.

Canadians should also alert their doctors about any heart problems they may have, or if they are on other medications or natural health products, or have had low blood levels of magnesium or potassium, before getting prescribed domperidone.

Health Canada and domperidone manufacturers are working to include the new safety information in the Canadian Product Monographs — reference documents for health-care professionals prescribing domperidone.