Soft drugs V: Thiazolidine-type derivatives of progesterone and testosterone.

Progesterone and testosterone are natural soft drugs, but to be used as drugs, their fast and facile metabolism must be prevented and their delivery controlled. A prodrug-soft drug combination can serve this purpose. Thiazolidines of testosterone, testosterone 17-propionate and progesterone were synthesized from the reaction of cysteine alkyl esters, N-methylaminoethanethiol, and mercaptamine and their hydrochlorides with the appropriate steroids. The thiazolidines function as bioreversible derivatives of the parent steroids.