Other safety alerts
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| The United States: Updated information about the drug interaction between methylene blue (methylthioninium chloride) and serotonergic psychiatric medications |
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Subsequent to previous safety communication posted on 26 July 2011, FDA is providing additional information about the reports of serotonin syndrome. Most cases from the FDA's Adverse Event Reporting System (AERS) of serotonin syndrome in patients given serotonergic psychiatric medications and methylene blue occurred in the context of parathyroid surgery, which involved the intravenous administration of methylene blue as a visualizing agent. Methylene blue doses ranged from 1 mg/kg to 8 mg/kg. Because methylene blue is not an FDA-approved drug at this time, and limited data exist regarding its use in various settings, it is not known whether there is a risk of serotonin syndrome in patients taking serotonergic psychiatric medications who are given methylene blue by other routes (e.g., orally or by local tissue injection) or at intravenous doses lower than 1 mg/kg. In addition, not all serotonergic psychiatric drugs have an equal capacity to cause serotonin syndrome with methylene blue. The cases of serotonin syndrome with methylene blue occurred in patients taking specific serotonergic psychiatric drugs, namely a selective serotonin reuptake inhibitor (SSRI), a serotonin norepinephrine reuptake inhibitor (SNRI), or clomipramine. It is unclear at this time whether intravenous methylene blue administration in patients receiving other psychiatric drugs with lesser degrees of serotonergic activity poses a comparable risk.
Please refer to the following website in FDA for details:
http://www.fda.gov/Drugs/DrugSafety/ucm276119.htm
In Hong Kong, Methylene Blue Inj (HK-59020) is registered by Sino-Asia Pharmaceutical Supplies Ltd. It is used in the treatment of methemoglobinemia. The news on the drug interaction with serotonin reuptake inhibitors has been released by Health Canada and was posted on the website of Pharmaceutical Service on 18 February 2011. A letter to inform healthcare professionals was issued on the same day and press release was issued on 21 February 2011. Previous safety communication of FDA was reported and posted on Drug Office website on 27 July 2011. A letter to inform healthcare professionals about the safety information was issued on the same day. The issue was discussed in the meeting of the Registration Committee of the Pharmacy and Poisons Board on 6 September 2011. The committee decided that the sales pack and/or package insert of pharmaceutical products containing methylene blue should include information about the potential drug interaction with serotonergic psychiatric medications as well as drug usage recommendations for emergency and non-emergency situations. Department of Health will keep vigilance against this issue.
Ends/ Friday, October 21, 2011
Issued at HKT 15:30
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