Protease inhibitors are : a) Saquinavir b) Nevirapine c) Nelfinavir d) Abacavir e) Efavirenz

**Core Concept**
Protease inhibitors are a class of antiretroviral medications that inhibit the protease enzyme in HIV, thereby preventing the maturation of viral particles and replication of the virus.

**Why the Correct Answer is Right**
These medications work by binding to the active site of the protease enzyme, which is essential for the cleavage of viral polyproteins. This inhibition prevents the formation of mature viral particles, thereby reducing the viral load in the body. Saquinavir, Nelfinavir, and other protease inhibitors are used as part of highly active antiretroviral therapy (HAART) to manage HIV infection.

**Why Each Wrong Option is Incorrect**
**Option A:** Saquinavir is a protease inhibitor, but the question asks for multiple options. This option is partially correct but not the complete answer.

**Option B:** Nevirapine is a non-nucleoside reverse transcriptase inhibitor (NNRTI), not a protease inhibitor. It works by binding to the reverse transcriptase enzyme and preventing its action.

**Option C:** Nelfinavir is a protease inhibitor, making it a correct answer. This option should be included in the correct answer list.

**Option D:** Abacavir is a nucleoside reverse transcriptase inhibitor (NRTI), not a protease inhibitor. It works by inhibiting the reverse transcriptase enzyme through chain termination.

**Option E:** Efavirenz is an NNRTI, similar to Nevirapine. It works by binding to the reverse transcriptase enzyme and preventing its action.

**Clinical Pearl / High-Yield Fact**
Protease inhibitors are often associated with gastrointestinal side effects, including diarrhea and nausea. Monitoring of liver function and lipid profiles is essential when using these medications.

**Correct Answer:** C. Nelfinavir