For phenadoxone (under its trade name of Heptalgin), and for pipidone, one microcrystal test for each was given in the second article of this series.[10] Recently another reaction of phenadoxone has been mentioned.[7] The remaining two substances, methadone (amidone, polamidon) and pethidine (dolantin, demerol, etc.) have been previously studied by a number of investigators, including two of the p