MISSION PHARMACAL's ORPHAN DRUG THIOLA WILL BE AVAILABLE

MISSION PHARMACAL's ORPHAN DRUG THIOLA WILL BE AVAILABLE beginning Nov. 1, following the approval of the drug Aug. 11. Thiola (tiopronin) is indicated for "the prevention of cystine (kidney) stone formation in patients with severe homozygous cystinuria with urinary cystine greater than 500 mg/day, who are resistant to treatment with conservative measures of high fluid intake, alkali and diet modification, or who have adverse reactions to d-penicillamine," approved labeling states. FDA, in a Sept. 22 "Talk Paper," also noted that the drug "serves as an alternative to d-penicillamine [Merck's Cuprimine and Wallace Labs' Depen], which has demonstrated fewer or less severe adverse reactions than d-penicillamine. Among those who had to stop taking d-penicillamine due to toxicity, 64.7% could take Thiola." The privately-held, San Antonio-based company also noted that "in those [patients] without prior history of d-penicillamine treatment, only 5.9% developed reactions of sufficient severity to require Thiola withdrawal." Licensed from the Japanese firm Santen Pharmaceutical, Thiola is Mission's fourth orphan drug for kidney stone disorders. The other products include Calcibind (cellulose sodium phosphate), Urocit-K (potassium citrate) and Lithostat (acetohydroxamic acid). The firm submitted the NDA for Thiola on Jan. 8, 1986. In its "Talk Paper," FDA estimates the U.S. population that can be helped with tiopronin at about 10,000. Thiola, Calcibind and Urocit-K were all developed by Mission in collaboration with Charles Pak, MD, of the University of Texas Southwestern Medical Center in Dallas, Texas. Research on the three drugs was supported, in part, with funds from the National Institutes of Health. Calcibind, approved in 1983, is indicated for patients with absorptive hypercalciuria. Urocit-K, which was approved in 1983, is indicated for patients with absorptive hypercalciuria. Urocit-K, which was approved the following year, is indicated for reduction of stone formation rate in patients with hypocitraturia. The "Talk Paper" notes "Dr. Pak was cited by the Public Health Service Orphan Product Board for his contributions in development of orphan drugs in March 1988 and has been continuing his work in this area." Pak, FDA continued, "has identified 18 separate stone-forming disorders and has developed selective treatments for each. These include use of drugs such as thiazide, a kidney stone drug, and changes in patients' diets when necessary, such as increasing water intake."