"I know each drug is designed differently but why is tamiflu resistant and Relenza isnt !!! Is Relenza inherently a better design hence the recent stockpile changes around the world. Does anyone know."
Are you implying revere completely glossed over the well documented differences in the way Tamiflu and Relenza bind in the "pocket" on the NA glycoprotein; fundamental to the understanding of antiviral drug resistance?
That would be admitting Relenza is inherently better.
Try reading here, it's old, but thanks to the usual bias in the media, it's still fresh,
Oseltamivir Resistance - Disabling Our Influenza Defenses by Anne Moscona, M.D. http://content.nejm.org/cgi/content/full/353/25/2633
There is no evidence of zanamivir resistance in viruses isolated from normal healthy patients after treatment with the drug. The only case of in vivo zanamivir resistance is that of an 18-month-old immunocompromised child, who acquired an influenza B virus infection and failed to respond to ribavirin treatment. The child was subsequently treated with zanamivir and after 12 days of treatment a virus containing an R152K NA mutation was isolated. This virus also contained a mutation in the HA protein, T198I, which had appeared prior to the NA mutation. In contrast, resistance to oseltamivir occurs in 1%-4% of adults and 4%-8% of the paediatric population.
Here's something no-one ever criticises Tamiflu for. It's all well and good that it is take orally, but IT CAN"T BE INJECTED.
"zanamivir is not used because it is an inhaler and patients in the recent Asian outbreak were too ill to inhale even though laboratory tests show it has some effects on H5N1. Manufacturers should think about producing an injectable form. Drugs that are administered intravenously can be better absorbed in patients who have stomach and acidity problems. We don't have to worry about absorption, injections take drugs right in. But if the patient takes them orally, maybe some amounts won't be absorbed or some may be destroyed by stomach acids. Intravenous zanamivir would also ensure faster onset, which would be critical in patients who are seriously ill. Orally taken drugs take 3-4 hours to reach maximum blood concentration and 3-4 hours is very critical in severe cases. But injectable zanamivir takes only 30 minutes to reach maximum blood concentration, this is a huge difference. With an intravenous antiviral, doctors can also vary the doses."
Q. So where's iv zanamivir? A. We don't need it because we worship the sun god Tamiflu... hang on, it's just gone supernova...what are we going to do n........
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