Linezolid is a new drug registered in Singapore in October 2000. It is available in the oral and parenteral form. It is a synthetic antibacterial agent of the oxazolidinone class.

Pre-marketing clinical data have indicated myelosuppression as a possible rare side effect. Recent post-marketing experience in the USA have raised the need to highlight this adverse reaction to all end-users due to the spontaneous reports of myelosuppression received by both Pharmacia and the US Food Drug Administration (FDA).

To ensure the safety and well-being of patients who receive linezolid, the following safety information will be added to the warnings section and the adverse reaction of the product insert:

Warning: Myelosuppression (including anaemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported in patients receiving linezolid. In cases where the outcome is known, when linezolid was discontinued, the affected haematologic parameters have risen toward pretreatment levels. Complete blood counts should be monitored weekly in patients who receive linezolid, particularly in those who receive linezolid for longer than two weeks, those with pre-existing myelosuppression, those receiving concomitant drugs that produce bone marrow suppression, or those with a chronic infection who have received previous or concomitant antibiotic therapy. Discontinuation of therapy with linezolid should be considered in patients who develop or have worsening myelosuppression.

Post-marketing Experience: Myelosuppression (including anaemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported during post-marketing use of Zyvox® (see Warnings). These events have been chosen for inclusion due to either their seriousness, frequency of reporting, possible causal connection to Zyvox®, or a combination of these factors. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made and a causal relationship cannot be precisely established.