Nucleoside reverse transcriptase inhibiting drug, which is a guanosine analogue is:-
**Core Concept**
Nucleoside reverse transcriptase inhibitors (NRTIs) are a class of antiretroviral drugs used to treat HIV infection. These drugs work by inhibiting the reverse transcriptase enzyme, which is essential for the replication of retroviruses like HIV. Guanosine analogues are a subgroup of NRTIs that mimic the structure of guanosine, a nucleoside base.
**Why the Correct Answer is Right**
Abacavir is a guanosine analogue NRTI that selectively inhibits the reverse transcriptase enzyme. It does so by incorporating into the viral DNA and causing chain termination during viral replication. Abacavir has a high affinity for the viral reverse transcriptase enzyme and is highly effective in suppressing HIV replication. The mechanism of action of abacavir involves the formation of a stable complex with the enzyme, leading to its inactivation.
**Why Each Wrong Option is Incorrect**
* **Option A:** Didanosine is a purine analogue NRTI, not a guanosine analogue.
* **Option B:** Lamivudine is a cytidine analogue NRTI, not a guanosine analogue.
* **Option D:** Zidovudine is a thymidine analogue NRTI, not a guanosine analogue.
**Clinical Pearl / High-Yield Fact**
NRTIs are a crucial component of antiretroviral therapy for HIV, and their use has significantly improved the prognosis for patients with HIV infection. However, long-term use of NRTIs can be associated with mitochondrial toxicity, which can lead to lactic acidosis and other metabolic disturbances.
**Correct Answer: C. Abacavir**