Is Oseltamivir (Tamiflu®) Safe? Re-examining the Tamiflu 'Ado' from Japan

Etsuji Okamoto

Disclosures

Expert Rev Pharmacoeconomics Outcomes Res. 2010;10(1):17-24. 

In This Article

Spontaneous ADR Reporting in Japan

Japan's spontaneous ADR reporting comes from either doctors/pharmacists or manufacturers. However, the majority of reports are those from manufacturers and reports from doctors/pharmacists are much fewer (28,500 from manufacturers vs 3891 from doctors/pharmacists in 2007 according to the MHLW). Doctors/pharmacists has been required to report ADRs to the MHLW since July 2003 by the Pharmaceutical Affairs Act but their compliance is far from satisfactory in the absence of a penalty against the dereliction of reporting. Furthermore, doctors/pharmacists are required to report only when they consider that the adverse events are related to the drugs and are not required to report any adverse events observed in the course of treatment. Even if patients demonstrate abnormal behaviors after the treatment of influenza, doctors are not required to report it unless they consider them to be caused by drugs (judgments that prescribing doctors do not normally welcome). As the ADR reporting system relies heavily on their subjective judgment, it is inherently biased by media coverage. Just 10 days (23 March–2 April 2007) after the MHLW issued a warning against the use of oseltamivir for teenagers on 20 March 2007, which prompted active media coverage, as many as 11 ADR reports were submitted from doctors.[102]

Reporting from manufacturers also has limitations. Manufacturers only have an obligation to report ADRs related to their products. In view of the situation that many manufacturers supply similar drugs and administering multiple medication is a common practice in Japan, even manufacturers' reporting, although more numerous than doctors/pharmacists, cannot give a complete picture.

Adverse drug-reaction reporting is reviewed by the Pharmaceuticals and Medical Devices Agency (PMDA) but reported forms are usually kept confidential. In the course of the debate over the safety of oseltamivir, however, the MHLW disclosed graphic images of spontaneous reporting forms over the website together with the dockets of the drug safety panel of the Drug and Food Advisory Committee. Five meetings have been held for the drug safety panel since March 2007, when the MHLW issued the warning, the latest of which was held on 16 June 2009.[103] The enormous documents published over the web provide a rare glimpse of individual cases. The summary of the data is included in Table 1.

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