Final answer:
The active metabolite of morphine most likely to have a clinical effect in renal failure patients is Morphine-6-glucuronide (Choice D).
Step-by-step explanation:
The active metabolite of morphine most likely to have a clinical effect in renal failure patients is Morphine-6-glucuronide (Choice D).
Glucuronidation is the primary pathway of morphine metabolism in the liver. Morphine-6-glucuronide is formed when morphine undergoes glucuronidation by the liver enzyme UDP-glucuronosyltransferase (UGT). This metabolite is pharmacologically active and has been found to accumulate in higher concentrations in patients with renal failure.
In contrast, Normeperidine (Choice A) is not a metabolite of morphine, but a metabolite of meperidine (pethidine). Normorphine (Choice C) is a metabolite of codeine. Codeine (Choice E) is a separate drug from morphine. And Morphine-3-glucuronide (Choice B) is a less pharmacologically active metabolite compared to Morphine-6-glucuronide.