ADR that result in revision of patient information
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| Canada: Summary Safety Review: Olanzapine: Assessing the potential risks of syndrome of inappropriate secretion of antidiuretic hormone and hyponatremia |
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Health Canada announces that it reviewed the potential risks of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and hyponatremia with the use of olanzapine. The safety review was triggered by a safety report completed by a manufacturer of olanzapine-containing products on the risk of hyponatremia secondary to SIADH, which was prepared following the identification of a published case report during routine surveillance.
Olanzapine is a prescription drug authorized for sale in Canada for the treatment of schizophrenia and related psychotic disorders, and bipolar disorder. When administered intramuscularly, it may also be used for the rapid control of agitation in these patient populations.
Syndrome of inappropriate secretion of antidiuretic hormone is a condition in which the body makes too much antidiuretic hormone, a hormone that helps regulate the water balance in the body. Too much antidiuretic hormone causes more water to be held in the body and commonly leads to hyponatremia, which is low blood sodium levels.
Symptoms of hyponatremia include muscle cramps, tremor, headache, nausea, and vomiting. If blood sodium levels become too low or if sodium levels drop too quickly, symptoms may progress to seizures, coma and respiratory arrest (absence of breathing), with life-threatening or fatal consequences.
Health Canada reviewed the available information provided by manufacturers, and from searches of the Canada Vigilance database and the scientific literature. Health Canada reviewed 15 cases (1 Canadian and 14 international) of SIADH or hyponatremia in patients taking olanzapine. Twelve of those cases (1 Canadian) reported SIADH and 3 reported hyponatremia only. Of the 15 cases, 13 (11 SIADH [1 Canadian], 2 hyponatremia) were found to be possibly linked to the use of olanzapine and 2 (1 SIADH, 1 hyponatremia) could not be assessed due to missing or contradictory information. Overall, these cases provided limited evidence for a link between the use of olanzapine and the development of SIADH and hyponatremia due to the presence of confounders (other factors that may have contributed to the occurrence of SIADH or hyponatremia) and missing clinical information.
Health Canada also reviewed 30 articles published in the scientific literature that investigated or summarized existing evidence for the association between antipsychotics (including olanzapine) and the development of SIADH and hyponatremia. Due to study limitations, including the presence of confounders, there was limited evidence to support a link between the use of olanzapine and the development of SIADH and hyponatremia.
Health Canada’s review could not confirm a definitive link between the use of olanzapine and the development of SIADH and hyponatremia. However, a possible link could not be ruled out.
While a definitive link could not be confirmed, Health Canada’s review of the available information could not rule out a possible link between olanzapine and the risks of SIADH and hyponatremia. Despite the limited available evidence, the extensive use of olanzapine in Canada and vulnerability of the patient population who could be prescribed the drug warranted a precautionary approach for these risks. Health Canada will work with the manufacturers to update the CPM for all olanzapine-containing products to include the potential risks of SIADH and hyponatremia.
Please refer to the following website in Health Canada for details:
http://dhpp.hpfb-dgpsa.ca/review-documents/resource/SSR1725462803755
In Hong Kong, there are 44 registered pharmaceutical products containing olanzapine. All products are prescription-only medicines. So far, with regard to olanzapine, the Department of Health (DH) has received 25 cases of adverse drug reaction, but these cases were not related to SIADH and hyponatremia. In light of the above Health Canada’s announcement, letters to inform local healthcare professionals will be issued, and the matter will be discussed by the Registration Committee of the Pharmacy and Poisons Board.
Ends/Friday, Nov 1, 2024
Issued at HKT 18:00
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