Tuesday, February 16, 2010

Zanamivir (Relenza) for HINI flu!

Zanamivir (Relenza) is an antiviral drug which is available an inhaler. The product is used with a device called a diskhaler. Relenza is also used to treat swine flu. Like Tamiflu is it only effective when given in the first 48 hours after the symptoms occur. At this time the virus is multiplying fast and once the drug is taken within the first 48 hours, the virus growth can be controlled. For the acute infection, Relenza should be taken for 5 days.

In North America the majority of people who have been infected with HINI have been treated with Tamiflu. However, few individuals with kidney disease and women who are pregnant have been treated with Relenza.

So far the data on the effectiveness of Relenza are lacking. From the few studies that have looked at the effects on Relenza on seasonal flu, it appears that the drug is working fine.

Relenza does not cure HNI but helps to:

- Reduce the intensity of the illness
- Decrease the number of sick days by about 1 day
- May reduce chances of developing complications

In children the benefits of Relenza have not been established. One study did show that Relenza did not prevent children from getting complications like ear infections nor did it reduce the duration of infection.

Zanamivir does have a few side effects, the most common is diarrhea. Moreover, Relenza can also worsen wheezing in asthmatics and should be used with great caution in smokers and people with COPD. Other reported side effects of Relenza include mental confusion, lack of concentration or unusual behavior. It appears that these behavior problems disappear once the drug has been discontinued.

Does Oseltamivir (Tamiflu) work for HINI?

There is some evidence that Tamiflu reduces the chances of acquiring swine flu. However, to prevent swine flu one needs to take the drug for 10 days. The drug is available both as a capsule and a liquid. However, oseltamivir is not frequently used to prevent flu in healthy individuals. The drug is only used to prevent swine flu in high risk individuals who may be at risk for developing complications from the infection after being exposed to someone who definitely has been diagnosed with swine flu. There are some individuals like asthmatics or those with AIDS who can develop serious complications after acquiring swine flu and in only these individuals is Tamiflu given for prevention.

To date, there is no good evidence to show that anti viral drugs like Tamiflu can prevent the infection in the long run. For example, if you take Tamiflu for 10 days, no one knows how long its protective effects last. Unlike a vaccine, these drugs are prohibitively expensive and one needs to take repeated courses to prevent the virus from causing an infection.

Moreover, there is always the possibility that the virus may mutate and change its shape and no longer be sensitive to the drug. Already cases of the mutated swine flu virus have been reported and these strains are resistant to Tamiflu.

Like all drugs, developing resistance to Tamiflu is a major concern.

Finally, Tamiflu also has side effects like nausea, vomiting and diarrhea. Thus, long term use may make the individual more prone to drug induced complications.

End point: Tamiflu is not 100 percent effective in prevention of the swine flu. From the few studies published the drug may reduce your chances of acquiring swine flu by 50-70 percent. One should also remember that many studies on Tamiflu are being conducted by people who are being paid by the makers of the drug- so there is always a bias in reporting.