Concept:
NPPA stands for National Pharmaceutical Pricing Authority.
Step 1: Role of NPPA.
NPPA fixes and regulates prices of essential medicines in India.
Step 2: Meaning of NLEM.
NLEM means National List of Essential Medicines. It contains medicines considered essential for healthcare.
Step 3: Price control.
Drugs listed in NLEM are brought under price regulation to make them affordable.
Step 4: Final answer.
Therefore, NPPA fixes price of drugs listed in NLEM.
\[
\boxed{\text{NLEM}}
\]