Comparison of aminobenzoate potassium and placebo in the treatment of scleroderma

To determine the safety and efficacy of aminobenzoate potassium (KPAB) in treating the skin manifestations of scleroderma.

Via a 48-week prospective, randomized, double blind, placebo controlled trial we compared the efficacy of KPAB 12 g/day with matching placebo. Outcome measures included skin mobility and thickening scores, patient and physician global assessments and, measurements of maximal oral aperture and hand range of motion.

Of 146 patients who entered the study, 76 (52%) completed. Demographics of the study population included age 49 +/- 13 years, 83% women, mean (range) disease duration was 104 (7-600) months. There were no differences in the demographics of the KPAB vs placebo nor the group that completed the study compared with the withdrawal group. There were no clinical or statistically significant differences between the KPAB and the placebo treated groups in any of the outcome measures. Subgroup analyses of skin mobility and skin thickening based on age, extent of disease, severity of disease, duration of disease and involved vs uninvolved skin were performed, but no differences were noted. The overall compliance to the medical regimen was > or = 75% in 93% of patients completing the study. Eighteen patients in the KPAB group and 6 placebo patients withdrew due to adverse drug reactions (ADR). The most common withdrawals for ADR were gastrointestinal intolerance and headaches. All ADR resolved following withdrawal of medication.

KPAB did not alter the skin changes of scleroderma in a group of patients with relatively longstanding stable disease. KPAB was reasonably well tolerated in this group of patients.