 Subsequently, Upjohn unexpectedly discovered that OHPA, unlike OHPC and progesterone, is orally active and shows marked progestogenic activity with oral administration, a finding that had been missed by the Schering researchers (who were primarily interested in the oil solubility of such esters).OHPA was found to possess two to three times the oral activity of 17α-methylprogesterone.Upjohn reported the oral activity of OHPA in the medical literature in 1957 and introduced the drug for medical use as Prodox in 25 mg and 50 mg oral tablet formulations later the same year.