Antiviral agents

Atazanavir is a selective, competitive, reversible inhibitor of HIV-1 protease. It interferes with the formation of essential viral proteins making them incapable of infecting other cells. Viral resistance develops rapidly when HIV-protease inhibitors are given alone and therefore they are used with other antiretrovirals.

Amprenavir is an HIV-protease inhibitor with antiviral activity against HIV. ft is used in the treatment of HIV infection and AIDS. Viral resistance emerges rapidly when amprenavir is used alone, and it is therefore used with other antiretrovirals.

Adefovir is converted intracellularly in stages to the di-phosphate, which then inhibits the DNA synthesis of hepatitis B virus through competitive inhibition of reverse transcriptase and incorporation into viral DNA. At high doses it has some activity against HIV.

Abacavir is converted intracellularly in stages to its active form carbovir triphosphate. This halts the DNA synthesis of retroviruses, including HIV, through competitive inhibition of reverse transcriptase and incorporation into viral DNA.

Influenza, commonly called “the flu,“ is caused by viruses that infect the respiratory tract. Compared with most other viral respiratory infections, such as the common cold, influenza infection often causes a more severe illness.

Since the introduction of zidovudine (AZT, Retrovir) in 1987, a relatively large number of drugs have been developed for the treatment of HIV-induced AIDS. Currently available antiretroviral drugs are subclassified based on their chemical structure and site of action as nucleoside reverse transcriptase inhibitors (NRTIs: zidovudine, didanosine, zalcitabine, stavudine, lamivudine and abacavir), non­nucleoside reverse transcriptase inhibitors (NNRTIs: nevirapine, delavirdine and efavirenz) and protease inhibitors (PIs: saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, and lopinavir). The use of these and all antiretrovirals as monotherapy is limited largely by the rapid development of viral resistance. Thus current Public Health Service HIV treatment guidelines recommend the use of drug combinations consisting of three or four anti-AIDS drugs.