Involved in biosynthesis of morphinan-type benzylisoquinoline alkaloids. Catalyzes the stereospecific conversion of salutaridine to salutaridinol. (7S)-salutaridinol + NADP(+) = H(+) + NADPH + salutaridine Subject to substrate inhibition at salutaridine concentrations higher than 20 to 30 uM. The enzyme does not obey Michaelis-Menten kinetics because the theorectical Vmax cannot be achieved due to strong substrate inhibition, instead the optimal velocity, Vopt, is taken as the measure of enzyme performance. Optimum pH is 6 for the reverse reaction (reduction) with activity decreasing sharply towards pH 4.5 and pH 7.5. Optimum pH is 9.5 for the forward reaction (oxidation) with greatly reduced activity at pH 6. Optimum temperature is 40 degrees Celsius. Has potential use in industrialized synthesis of the antitussivum codeine and the analgesic morphine. Belongs to the short-chain dehydrogenases/reductases (SDR) family.