Final answer:
The first-gen single drug therapy for HIV was AZT, approved in 1987, which blocks viral replication by inhibiting reverse transcriptase. Due to the virus's high mutation rate, this led to HAART, a drug combination therapy to combat resistance, with newer drugs like Raltegravir joining the regimen.
Step-by-step explanation:
The first generation single drug therapy for HIV was azidothymidine (AZT), also known as zidovudine or by its brand name, Retrovir. Approved in 1987, AZT became a groundbreaking treatment as it works by inhibiting the HIV reverse transcriptase enzyme, thus blocking further replication of the virus. This initiation of antiretroviral treatments marked a significant step forward in the fight against AIDS. Eventually, this evolved into the pioneering strategy of highly active antiretroviral therapy (HAART), a combination of drugs, including reverse transcriptase inhibitors and protease inhibitors, aimed at reducing the occurrence of drug resistance due to the high mutation rate of the HIV virus.
Despite the advancements, the rapid mutation of HIV means resistance to single-drug therapies can develop swiftly, necessitating the development of new treatments and the use of drug "cocktails". Drugs such as Raltegravir (Isentress), which inhibits the integration of viral DNA into the host genome, represent newer additions to the anti-HIV arsenal, reflecting ongoing efforts to combat the disease's evolution and improve patient outcomes.