Which biochemical pathway is important to control oxidative drugs such as methyldopa and primaquine?

• A. Pentose phosphate pathway
• B. Urea Cycle
• C. Beta oxidation
• D. Porphyrin metabolism

Answer: (A)

NADPH production to fuel antioxidant defenses is what matters here. The oxidative branch of the pentose phosphate pathway generates NADPH, the reducing power needed to convert oxidized glutathione back to its active form. This glutathione system neutralizes reactive oxygen species produced by some drugs, including primaquine, helping protect red blood cells from oxidative damage. Red blood cells rely on this pathway because they lack mitochondria, making the PPP the primary source of NADPH. If NADPH production falters, as in G6PD deficiency, oxidative drugs can trigger hemolysis. The other pathways listed don’t provide NADPH for this detoxifying system: the urea cycle handles nitrogen disposal, beta oxidation breaks down fatty acids, and porphyrin metabolism is about heme synthesis.