A process for purifying plant extracts which consist essentially of noroxymorphone compounds and which comprise, as impurities, &alpha；,&bgr；-unsaturated noroxymorphone compounds, by (a) converting the plant extract or the product of a subsequent stage in the synthesis of a selected noroxymorphone compound in a reaction which converts the hydroxyl groups present in the mixture to leaving groups of the formula &mdash；OR2 in which R2 is the introduced radical of the leaving group, (b) these leaving groups are optionally detached again, then (c) the resulting mixture is subjected to a selective hydrogenation, so that a saturated bond is formed in the &alpha；,&bgr；-position of the unsaturated noroxymorphone compounds and any remaining leaving groups are each converted to a hydroxyl group and then optionally (d) the pure noroxymorphone compound is isolated； processing of the noroxymorphone purified in this way to naltrexone or naloxone or a salt of these compounds or a quaternary derivative of these compounds； pharmaceutical formulations comprising such a compound.
