(87) (+) -4 -dimethylamino-1, 2-dipheny 1-3-methyl-2 Butanol propionate, (the international non-proprietary name of which is Dextropropoxyphene), and its salts, preparations, admixtures, extracts and other substances containing any of these drugs, except preparations) for oral use containing not more than i 35 miligrammes of Destroproposyphene base per dosage unit or with a concentration of not mo