Azithromycin: Increased rate of relapses of haematological malignancies and mortality in haematopoietic stem cell transplantation (HSCT) patients treated with azithromycin

Pfizer Pte Ltd would like to inform healthcare professionals about the increased rate of relapses of haematological malignancies and mortality in Haematopoietic Stem Cell Transplantation (HSCT) patients treated with azithromycin. This was based on the results of a clinical trial, ALLOZITHRO, which detected an increased risk of haematological relapses in patients treated with azithromycin compared with placebo [adjusted Hazard Ratio (95% CI) = 1.6 (1.12-2.4)]. The clinical trial investigated long-term azithromycin exposure to prevent bronchiolitis obliterans syndrome (BOS) in patients who underwent allogeneic HSCT for haematological malignancy. While it was not clear how azithromycin could have contributed to the observed higher rate of haematological relapses in the study, it was concluded that long-term azithromycin exposure following HSCT may include risks which outweigh the anticipated benefits.  In Singapore, azithromycin is not approved for the prevention of BOS. Please refer to the letter for more details.

Only abstracts of the Dear Healthcare Professional Letters (DHCPL) are provided on this website. Details of these letters can be found in the MOH Alert System, which is accessible via the Health Professionals Portal (HPP), a one-stop portal for all healthcare professionals in Singapore. Dentists, medical doctors and pharmacists may access HPP at https://hpp.moh.gov.sg ↗ (opens in new tab) and follow the procedures below to access the MOH Alert system.

Step 1: Select your profession under ‘For Healthcare Professionals’.

Step 2: Click on ‘Useful links’.

Step 3: Click on ‘MOH Alert’ and log in via Singpass.

Step 4: Click on ‘Drug Alerts’ or ‘Med Device Alerts’ to view the DHCPLs.