Human Immunodeficiency Virus (HIV) infection is a life threatening condition. The virus is transmitted sexually or by infusion of infected blood. In women infected with HIV virus, the virus is transmitted to the baby during childbirth and while breastfeeding.
HIV infection leads to Acquired Immunodeficiency Syndrome (AIDS), which severely weakens the immune system. HIV infection cannot be cured. However, its progression can be delayed with appropriate treatment. The goal of HIV treatment is to suppress replication of the viruses.
As different types of drugs target different HIV strains, combination therapy comprising of at least three classes of anti-HIV medications is used for increasing the lifespan and improving the quality of life of people diagnosed with HIV or AIDS.
Drugs and Medications to Treat HIV
Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
HIV is classified as a retrovirus. When a retrovirus attacks a CD4 cell or specialized immune cell in the body, it transfers its genetic material or DNA into the genome of the cell. The HIV virus acts in an abnormal manner. Unlike normal cells that carry their genome in the DNA, the HIV carries its genome in the RNA.
The enzyme reverse transcriptase helps to make copies of the DNA from the RNA genome of the retrovirus. The DNA of the virus is then inserted in the chromosome of the host cell. NNRTIs work by inhibiting the activities of the enzyme reverse transcriptase, thereby suppressing multiplication of the viruses. NNRTIs used for treating HIV infection include Efavirenz, Nevirapine, Etravirine and Rilpivirine.
Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
Just as NNRTIs, NRTIs also work by inhibiting the activities of the enzyme reverse transcriptase. By supplying defective building blocks to reverse transcriptase, NRTIs prevent conversion of the RNA in HIV into DNA, thereby preventing the retrovirus from replicating. NRTIs used for HIV infection treatment include Abacavir, Tenofovir, Emtricitabine, Zidovudine and Lamivudine.
Protease Inhibitors (PIs)
To produce new HIV particles, the infected CD4 cell require protease enzyme. By blocking the protease enzyme, the anti-HIV drugs called protease inhibitors prevent production of new viruses.Protease inhibitors approved for treating HIV infection include atazanavir, ritonavir, darunavir and fosamprenavir. A protease inhibitor is combined with at least two other anti-HIV medications to prevent progression of the disease.
Fusion inhibitors, also known as entry inhibitors, block entry of HIV into healthy CD4 cells. Their mode of action is different from that of the aforementioned anti-HIV medications. While NNRTIs, NRTIs and PIs work after a healthy CD4 cell is infected with HIV, fusion inhibitors protect a healthy immune cell from the virus.
Some fusion inhibitors attach themselves to the proteins on the surface of the healthy CD4 cell, whereas others target the protein on the surface of HIV. As the protein of HIV cannot bind to the protein on the surface of CD4 owing to the presence of the fusion inhibitor, it cannot enter the healthy immune cell. Fusion inhibitors currently recommended for treatment include maraviroc and enfuvirtide.
Integrase is an enzyme that helps HIV to insert its genome in the CD4 cell. Integrase inhibitors are anti-HIV drugs that obstruct the activities of the viral enzyme integrase.Raltegravir is an integrase inhibitor recommended for treating HIV infection.