Oseltamivir adverse effects

The most frequently reported adverse effects of oseltamivir are nausea and vomiting. These events are usually mild to moderate, occur during the first 1 to 2 days of treatment, and can be lessened by taking the drug with food. Bronchitis, insomnia, and vertigo may also occur. 

Adverse Effects. Oral administration of oseltamivir can cause gastrointestinal disturbances such as nausea, vomiting, diarrhea, and abdominal cramps. Zanamivir, which is administered by inhalation, is associated with bronchospasm and reduced opening of the airway. The adverse effects of zanamivir can be quite severe in people with bronconstrictive disease (asthma, chronic obstructive pulmonary disease), and this drug should probably be avoided in these individuals. 

Oseltamivir is administered as an oral capsule and zanamivir by inhalation. Inhaled zanamivir has fewer adverse effects than oral oseltamivir, but there are concerns about its use in young and elderly patients, who are generally unable to achieve the inspiratory flow rate needed to ensure adequate lung deposition (2). Oral oseltamivir is more convenient and easier to administer, but needs to be given with food to lower the frequency of gastrointestinal adverse effects. 

Oseltamivir (GS4104) is an ester prodrug, whose active metabolite (GS4071) is a potent selective inhibitor of influenza virus neuraminidase, to which it is rapidly hydrolysed by hepatic carboxylesterases. The metabolite is then completely excreted by the kidneys by filtration and secretion. In animals oseltamivir had a wide safety margin, with no evidence of teratogenicity or adverse effects on fertility. Oseltamivir has also been studied in the treatment and prevention of influenza A and B, but published results are sparse. To date it has been well tolerated. Headache was the most frequent complaint and mild to moderate gastrointestinal adverse effects (nausea, diarrhea) have been described (3). 

In 730 residents of nursing homes who took oseltamivir prophylaxis for a median of 9 days (range 5-12), adverse effects were identified in 30 (4.1%), of whom 20 had one adverse effect and 10 had two (12). The most common adverse effects were diarrhea (n = 12), nausea or vomiting (n — 7), cough (n = 5), and confusion (n — 4). 

Adverse effects of neuraminidase inhibitors are bronchospasm with zanamivir, which is inhaled, and gastrointestinal disturbances with oseltamivir. 

The relation between oseltamivir and adverse behaviors was investigated in a large epidemiological study in Japan in the winter of 2006-2007 and the preliminary results were reported in Japanese oseltamivir had no adverse effects [256. However, the statistical analysis of the results has been criticized, and it has been suggested that a more appropriate analysis shows that the rate ratio of psychiatric adverse reactions to oseltamivir was 1.57 (95% Cl = 1.34, 1.83) [257. Two other studies have since been published. 

In a cross-sectional online survey of oseltamivir prophylaxis in 95 school children with confirmed influenza A (HlNl) in London in April-May 2009, only 48% of the primary schoolchildren completed a full course, compared with 76% of the secondary school children [260 ]. Mild neuropsychiatric adverse effects were reported by 18% of the children. 

Zanamivir was generally well tolerated in clinical trials (Fleming 2003). During treatment with oseltamivir, nausea and vomiting have been reported as side effects (Oxford 2005). A small number of severe adverse reactions in children, including neuropsychiatric events and skin hypersensitivity, have, however, been reported, primarily in Japan which has the highest use of oseltamivir (Li et al. 2007). 

Drug overdose The pattern of episodes of oseltamivir overdose as reported to Texas poison centers during 2000-2008 has been described [157 ]. Of 298 cases, 92% occurred in December-March (i.e. primarily during outbreaks of influenza), 77% involved patients aged 0-19 years, 73% resulted from therapeutic errors, 90% were managed on-site, and 80% had no effect. The most common adverse reactions were vomiting (7.5%), nausea (3.8%), and abdominal pain (3.8%). 

Strong M, Burrows J, Stedman E, Redgrave P. Adverse drug effects following oseltamivir mass treatment and prophylaxis in a school outbreak of 2009 pandemic influenza A(HINI) in June 2009, Sheffield, United Kingdom. Euro Surveill 2010 15(19) pii/19565. 

Psychiatric There is some controversy about the potential of oseltamivir to cause adverse neuropsychiatric effects, since concerns were raised about the risk of hallucinations, delirium, and abnormal activity [253, 254 ]. Even deaths have been reported [255. ... 

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