Volume 19, Issue 1 (January 1974)
Determination of Propoxyphene in Biological Materials
Propoxyphene is 4-dimethylamino-3-methyl-1, 2-diphenyl-2-butanol propionate. The dextrorotatory salt is a very popular prescription analgesic marketed as Darvon®. The levorotatory product, which is not especially popular as an antitussive, is marketed as Novrad®. Dextropropoxyphene hydrochloride is very soluble in water (2 g/ml) and is marketed in capsules by itself and together with acetylsalicylic acid, phenacetin, caffeine, and also a tranquilizer. The capsules usually contain 32 or 65 mg of dextropropoxyphene hydrochloride. Unfortunately, the ready solubility of the hydrochloride has allowed for easy abuse of this drug by injection. A capsule which contained the drug in a spherical tablet also allowed the easy separation of this drug from other ingredients. This form has been discontinued. In an effort to prevent the misuse of the drug and to increase its safety, the manufacturer has produced a water-insoluble salt (1.5 mg/ml), propoxyphene napsylate, or the 2-naphthalene sulfonate which is marketed as Darvon-N®. Because of the weight of the salt this product is supplied in 50- and 100-mg dosage forms as tablets and a suspension containing 50 mg of Darvon-N® per 5 ml. The tablets are film-coated. The insolubility of this product should restrict its abuse and might prevent deaths by allowing for a much slower absorption of the drug.