Catalyzes the stereospecific reduction of methylecgonone to methylecgonine, the penultimate step in cocaine biosynthesis. Can also use 6-hydroxytropinone, tropinone and nortropinone as substrates, but not 8-thiabicyclo[3.2.1]octan-3-one (TBON), cyclohexanone, cyclooctanone or N-methyl-4-piperidone. NADH can substitute for NADPH, but with a decreased activity. ecgonine methyl ester + NADP(+) = ecgonone methyl ester + H(+) + NADPH Strongly inhibited by Cu(2+) and Zn(2+) and to less than 30% by Co(2+) and Fe(2+). kcat is 0.24 sec(-1) for ecgonone methyl ester. kcat is 0.121 sec(-1) for NADPH. kcat is 5.538 sec(-1) for ecgonine methyl ester. kcat is 5.238 sec(-1) for NADP(+). Optimum pH is 6.8-9.8. Expressed in young leaves. Detected in stems and flowers, but not in mature leaves or roots. Expressed in the palisade and spongy mesophyll tissue of leaves and sepals. Belongs to the aldo/keto reductase family.