Treatments for AIDS are an alphabet soup of drug names and drug families. Since the goal of treatment is to reduce the viral load as much as possible, effective treatment requires arresting multiple phases of viral activity. Some drugs prevent entry of HIV into the cell, other drugs prevent the virus from entering the cell's DNA and still others inhibit different steps in the process by which the viral DNA becomes RNA.
NRTIs and NtRTIs
According to the Mayoclinic.com, NRTI stands for nucleoside analogue reverse transcriptase inhibitor. This family of AIDS drugs prevents the synthesis of DNA from RNA by inhibiting the enzyme reverse transcriptase.
The early breakthrough AIDS drugs were NRTIs. For example, zidovudine, popularly known as AZT was approved in 1987. It was followed by many other NRTIs, all of which except one, end with the letters "ine."
NtRTI stands for nucleotide reverse transcriptase inhibitor. As of 2010, there is only drug in this category. The mechanism of action for NtRTIs is very similar to NRTIs in that it also prevents synthesis of DNA from RNA. The difference is that it mimics a different genetic building block--a nucleotide instead of a nucleoside--to do so
Protease Inhibitors
Proteases are a class of enzymes that cleave proteins used in the assembly of new viruses. According to Mayoclinic.com, HIV particles "become structurally disorganized and noninfectious" when proteases are inhibited,
The first protease inhibitor, saquinavir, was approved by the FDA in 1995. Many new proteases--all of which end in the letters "avir," quickly followed.
NNRTIs
NNRTI stands for non-nucleoside reverse transcriptase inhibitors. Whereas NRTIs gum up the process of viral replication by mimicking a nucleoside, NNRT deactivates reverse transcriptase by binding directly to it. As of 2010, there are four drugs in this category.
Fusion Inhibitors
Unlike other drugs, fusion inhibitors act before the virus even enters the cell. Viruses act by penetrating the cell membrane and becoming integrated into the cellular DNA. According to Reference.MD, fusion inhibitors block the attachment of the virus to the CD4 receptor on the cell membrane. Fusion inhibitors are used after other drugs have been exhausted. As of 2010, Fuzeon is the single approved drug in this category, but others are in the pipeline.
Integrase Inhibitors
Just as fusion inhibitors block the entry of the virus into the cell, integrase inhibitors block the entry of the virus into the cellular DNA. PubMeds Health explains that at present, there is only a single drug called raltegravir in this category. Integrase inhibitors are designed to be used with other anti-retroviral drugs.
