Final answer:
AZT was the first drug approved for AIDS treatment and works by inhibiting HIV replication. Drug resistance due to HIV's high mutation rate led to the development of HAART, which combines multiple drugs to combat this issue. The constant evolution of HIV necessitates ongoing drug research and development.
Step-by-step explanation:
Understanding HIV Treatment and Drug Resistance
Initially, AZT (azidothymidine) was the first drug approved for AIDS treatment in 1987. It is a nucleoside reverse transcriptase inhibitor (NRTI) that disrupts the replication of HIV by inserting itself in place of the natural nucleotide, but because it lacks a 3'OH group, it terminates the elongation of the viral DNA.
In the past 10 years, other drugs also targeting reverse transcriptase and various stages of the HIV life cycle have been developed. Drugs that inhibit entry, integrate inhibitors, and prevent virus assembly have contributed to making HIV a manageable chronic condition.
However, the effectiveness of these drugs can be compromised over time due to the high mutation rate of HIV, leading to drug resistance. This challenge led to the creation of HAART (highly active antiretroviral therapy), combining multiple drugs to decrease the likelihood of resistance. Even so, complete eradication of HIV is elusive as it hides in immune cells and resurfaces if treatment stops. Thus, new drug development continues to adapt to the evolving virus.