Vol.65 No.3 May 2017
Postmarketing surveillance of linezolid
1)Medical Affairs, Pfizer Essential Health, Pfizer Japan Inc., Shinjuku Bunka Quint Bldg., 3-22-7 Yoyogi, Shibuya-ku, Tokyo, Japan
2)Post Marketing Study Strategy and Management, Pfizer Japan Inc.
3)Japan Clinical Informatics & Innovation, Pfizer Japan Inc.
Abstract
Linezolid (Zyvox®) was approved for the additional indication of treatment of patients with linezolid-sensitive methicillin-resistant Staphylococcus aureus (MRSA) infection in April 2006. Subsequently, postmarketing surveillance of linezolid was conducted from August 2006 to March 2010, and the data of 978 patients were collected from 127 study sites. Data from 970 and 431 patients, respectively, were used to analyze the safety and efficacy of linezolid for the additional indication. The following results were obtained:
1) Adverse drug reactions were reported in 16.8% (163/970) of patients, which was lower than that reported at the time of the regulatory approval (55.00%). The most common adverse drug reactions were thrombopenia (78 patients), anaemia (31 patients), thrombocytopenia (26 patients), leukocytopenia (12 patients), bone-marrow dysfunction (8 patients), abnormality of hepatic function (6 patients), superinfection (5 patients), and diarrhoea (5 patients). Serious adverse drug reactions occurred in 50 patients (63 events); however, most of these events were clinically manageable, and in the patients in whom the events did not reverse or resolve, the primary disease/complications was considered to be responsible.
2) We focused on adverse drug reactions involving the hematopoietic system. Although the incidence of adverse drug reactions involving the hematopoietic system was not high, we consider that periodic examination of the blood is necessary for appropriate management of the adverse drug reactions according to the precautions listed in the approved labeling. The effects of age, body weight and duration of drug administration (total dose) on the safety were also investigated as investigation items of special interest. Since no new safety concerns were identified from these investigations, it was concluded that there was no need for the adoption of any additional safety measures.
3) Of the 431 patients included in the efficacy analysis, the drug was assessed as clinically effective in 90.5% (390/431). This percentage was higher than the percentage of 62.9% (39/62) in patients with MRSA infection reported at the time of the regulatory approval. The clinical efficacy and bacterial eradications rates were high (91.1% and 77.0%, respectively) in patients infected with S. aureus, which was the most commonly identified causative pathogen.
These results confirm the high clinical usefulness of linezolid even under actual usage conditions.
Key word
linezolid, postmarketing surveillance, safety, effectiveness, MRSA
Received
November 4, 2016
Accepted
December 22, 2016
Jpn. J. Chemother. 65 (3): 491-509, 2017
