Other safety alerts
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| The United Kingdom: Xaqua (metolazone) 5mg tablets: exercise caution when switching patients between metolazone preparations |
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Medicines and Healthcare products Regulatory Agency (MHRA) announces that prescribers and dispensers should use caution if switching patients between different metolazone preparations as the rate and extent of absorption of metolazone are formulation dependent. This can impact the bioavailability of the product.
Healthcare professionals have expressed concerns to the MHRA with respect to switching patients between metolazone preparations due to potential differences in the bioavailability and dosing instructions between Xaqua and unlicensed imported metolazone preparations.
The MHRA sought independent advice from Expert Advisory Groups of the Commission on Human Medicines, which recommended that the Marketing Authorisation Holder for Xaqua circulate a letter to healthcare professionals to reinforce key messages about initiating metolazone treatment or switching to Xaqua. In addition, the product information for Xaqua has been updated to clarify that references to comparative bioavailability with other metolazone products relate specifically to Metenix (a formerly licenced product, which was withdrawn in the United Kingdom in Mar 2012 for commercial reasons) and not to any other metolazone preparations. Metenix is the only product for which there is comparative bioavailability data.
Specialists are advised to prescribe the licensed product Xaqua when initiating metolazone treatment rather than an unlicensed imported metolazone preparation. Currently, there is no national United Kingdom guidance on the use of metolazone. However, local guidance may be available in the form of shared care, prescribing and monitoring and/or clinical specialty guidelines. Individual patient factors should be considered before initiating metolazone treatment.
Specialists should manage the switching of patients already taking an unlicensed imported metolazone product to Xaqua. Individual patient factors should be considered. Arrangements for monitoring should be made on an individual basis after an assessment of the individual clinical risk. If switching to Xaqua is appropriate, the dose of metolazone provided as Xaqua may need to be adjusted to take account of individual patient factors, and the difference in bioavailability between Xaqua and the metolazone preparation being replaced (where that information is available). In the absence of comparative bioavailability data to inform a dose recommendation, an option may be to reduce the dose by half and/or adjust the frequency of dosing of Xaqua. The dose can then be titrated upwards under increased monitoring, if necessary. If switching is not considered clinically appropriate it should be highlighted to the patient precisely which metolazone preparation they are receiving (including manufacturer, brand name (if available) and dose). The prescription and supply of metolazone should be product-specific and documented clearly, especially for transfers of care.
Please refer to the following website in MHRA for details:
http://www.gov.uk/drug-safety-update/xaqua-metolazone-5mg-tablets-exercise-caution-when-switching-patients-between-metolazone-preparations
In Hong Kong, there is no registered pharmaceutical product containing metolazone.
Ends/Thursday, Jan 26, 2023
Issued at HKT 16:00
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