Tamiflu is the current standard treatment for patients with influenza. A recent study has presented results demonstrating that treatment with Tamiflu reduces the time to relief of flu symptoms, however, increases the occurrence of nausea and vomiting.
Tamiflu (Oseltamivir) is a neuraminidase inhibitor that blocks the activity of influenza virus enzymes. During the 2009 influenza pandemic, Tamiflu was used extensively, however there remains some debate over its effectiveness.
A recent meta-analysis reported in the Lancet has reviewed all available randomised clinical trials of Tamiflu in adults, including its side effects and potential complications. The primary outcome assessed by the study was the time until all symptoms subsided. The symptoms included in the study were: nasal congestion, sore throat, cough, aches and pains, fatigue, headaches, and chills/sweats.
In total, 9 trials were included in the analysis, with a total of 4328 influenza patients. The study found that Tamiflu reduced the time to alleviation of symptoms compared with the placebo group. The median time reported for symptoms to subside in the Tamiflu treatment group was 97.5 hours, compared with 122.7 hours in the placebo group. In addition, treatment with Tamiflu was shown to decrease the risk of lower respiratory tract complications, and reduced hospital admittance. There were no serious adverse events reported; however, Tamiflu did increase the risk of both nausea and vomiting. The authors reported that the estimated increases for nausea and vomiting (3.7% and 4.7%, respectively), are similar to what is seen with antimicrobial drugs.
There are several clinical trials currently recruiting participants for treatment with Tamiflu (oseltamivir), two of which are evaluating treatment in combination with other anti-viral drugs. The first study aims to assess the effectiveness of a combination of the anti-viral drugs; amantadine, Tamiflu, and ribavirin, compared with Tamiflu treatment alone. This study, conducted by National Institute of Allergy and Infectious Diseases (NIAID), will be carried out at 84 locations across the United States, Argentina, Australia, Mexico, and Thailand. Participants will be recruited if they are 18 years of age or older, and are at risk of complications from influenza. Participants will be randomly allocated to either take Tamiflu alone, or in combination with amantadine and ribavirin.
The second study assessing Tamiflu in combination is being conducted by Vertex Pharmaceuticals Incorporated, in collaboration with Janssen Pharmaceuticals, and is recruiting participants at 121 study locations across the United States and Puerto Rico. It is a phase 2 study that aims to determine the time to recovery from influenza when patients are treated with VX-787 both alone, and in combination with Tamiflu. Patients who present with flu-like symptoms (including fever, at least one respiratory symptom and at least one systemic symptom), will be recruited to participate in the study.
Dobson, J, Whitley, R.J, Pocock, S, Monto, A.S. “Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials” Lancet Available online 30 January 2015 doi:10.1016/S0140-6736(14)62449-1
Clinicaltrials.gov “Comparing the Efficacy, Safety, and Tolerability of Combination Antivirals (Amantadine, Ribavirin, Oseltamivir) Versus Oseltamivir for the Treatment of Influenza in Adults at Risk for Complications (IRC003)” Available from: https://www.clinicaltrials.gov/ct2/show/NCT01227967?term=tamiflu&recr=Open&no_unk=Y&rank=6 Last Accessed: Feb 19, 2015.
Clinicaltrials.gov “A Study of Acute Uncomplicated Seasonal Influenza A in Adult Subjects” Available from: https://www.clinicaltrials.gov/ct2/show/NCT02342249?term=tamiflu&recr=Open&no_unk=Y&rank=9 Last Accessed: Feb 19, 2015.
Image courtesy of David Castillo Dominici at FreeDigitalPhotos.net
Written by Deborah Tallarigo, PhD