Analysis of Oseltamivir(Tamifluⓡ) Adverse Reactions Reported to Regional Pharmacovigilance Center of Ajou University Hospital

Abstract

Background : Oseltamivir is an antiviral agent for the treatment and prophylaxis against influenza (A or B). During the 2009 pandemic of the H1N1 influenza, the use of oseltamivir rapidly increased worldwide. Further, with the increasing use of this agent, the number of reported adverse drug reactions (ADRs) to this drug, also had been increased. Korean Food and Drug Administration (KFDA) promoted intensive monitoring of oseltamivir associated ADRs, from August 2009 to January 2010.

Method : Regional Pharmacovigilance Center of Ajou University Hospital participated in the KFDA program by collecting ADRs of oseltamivir. ADRs were collected both, by voluntary reports and tele-monitoring, from January 2009 to December 2010. This included the oseltamiviradverse reaction intensive monitoring period set by the KFDA. Severity and causality assessments were done by using WHO-UMC (Uppsala monitoring center) causality assessment system.

The ADRs were evaluated for the symptoms of the organ systems and the age groups. The relationship between the number of ADRs and the number of prescriptions was analyzed.

Results : A total of 359 cases were collected. Eleven cases with unknown age and gender were not included. Causality Assessment showed 17.0% ’probable’ and 80.8% ’possible’, with no ’certain’ cases. The most commonly reported events were gastrointestinal reactions (n=244, 59.7%), followed by neuropsychiatric cases (n=67, 16.4%). There were 24 (7.0%) serious adverse events (SAE).

The most frequent reports were in the age group of 1 to 11 (n=182, 2.8%), with the greatest number of prescriptions. A noteworthy finding was that the frequency of neuropsychiatric reactions was the highest in the adolescent group. There were rare cases of ADRs, such as nightmare, hallucination, and neuropsychiatric change.

Conclusions : The number of prescriptions and ADRs tends to increase in the younger age group. In causality assessment, there was more ’possible’ grade comparing to the other ADR data from Ajou Pharmacovigilance Center. Gastrointestinal adverse reactions are the most occurred ADRs. Neuropsychiatric adverse reaction occurred most in the adolescent group.