<s>[INST] context: ANTIVIRAL DRUGS: CLASSI FICATION 1.Anti-Herpes virus Idoxuridine, Acyclovir, Valacyclovir, Famciclovir, Ganciclovir*, Foscarnet* 2 Anti-Retrovirus (a) Nucleoside reverse transcriptase inhibitors (Nis): Zidovudine (AZT), Didanosine, Zalcitabine*, Stavudine, Lamivudine, Abacavir (b) Nonnucleoside reverse transcriptase inhibitors (NNis): Nevirapine, Eirenz, Delavirdine* (c) Protease inhibitors: Ritonavir, Indinavir, Nelfinavir, Saquinavir, Amprenavir*, Lopinavir 3.Anti influenza virus: Amantadine, Rimantadine*,oseltamivir 4. Nonselective antiviral drugs: Ribavirin, Lamivudine, Adefovir dipivoxil, Interferon alpha. * Not yet marketed in India. Oseltamivir (TAMIFLU): This recently developed antiinfluenza virus drug has a broader-spectrum activity covering influenza A (amantadine sensitive as well as resistant), influenza B and an-influenza (bird flu) H5Nl and other strains. It is an ester prodrug that is rapidly and nearly completely hydrolysed during absorption in intestine and by liver to the active form oseltamivir carboxylate. The active metabolite is not fuher metabolized and is excreted by the kidney with a tV! of 6--10 hours. It acts by inhibiting influenza virus neuraminidase enzyme which is needed for release of progeny virions from the infected cell. Spread of the virus in the body is thus checked. Oseltamivir is indicated both for prophylaxis as well as treatment of influenza A, B and bird flu. Staed at the onset of symptoms, it reduces the severity and durationof illness. However, considering the cost, and to preserve its efficacy, use should be restricted to high risk subjects. Dose: therapeutic 75 mg oral BD for 5 days; prophylactic 75 mg OD. Side effects are nausea and abdominal pain due to gastric irritation (reduced by taking the drug with food), headache, diarrhoea, cough and insomnia. Skin reactions have been repoed. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:767,777 [/INST] question: An influenza is treated by: | options: A: Amantadine B: Ribavarin C: Cidofovir D: Oseltamivir | answer: D </s>