Safety and pharmacokinetics of recombinant human relaxin in systemic sclerosis

James R. Seibold, Philip J. Clements, Daniel E. Furst, Maureen D. Mayes, Deborah A. McCloskey, Larry W. Moreland, Barbara White, Fredrick M. Wigley, Susan Rocco, Mark Erikson, John F. Hannigan, Martin E. Sanders, Edward P. Amento

Research output: Contribution to journalArticlepeer-review


Objective. To investigate the safety and pharmacokinetics of a 28 day continuous subcutaneous infusion of recombinant human relaxin in patients with systemic sclerosis with diffuse scleroderma. Methods. Thirty patients with stable diffuse scleroderma of moderate severity received recombinant human relaxin at 6, 12, 50, 100, and 200 μg/kg/day or placebo in a double blind, sequential panel, dose escalation study. Results. All patients completed 28 days of study treatment. Steady state concentrations of serum relaxin were achieved by the 3rd day of infusion and were close proportionate. Patients receiving 200 μg/kg/day achieved levels about 50- fold those of normal pregnancy. Pharmacokinetics of relaxin were nonlinear with hyperbolic increases of both t( 1/4 ) and volume of distribution and parallel decrease of elimination rate coefficient. An elimination transport system was suggested with saturation at serum relaxin concentration of 45 ng/ml. Adverse events included local infusion site rash and pain, minor bleeding episodes, and decreased hemoglobin concentration (mean reduction 1.1 g/dl). Standard measures of scleroderma were unchanged, although global assessment favored relaxin over placebo. Conclusion. Recombinant human relaxin in the doses used was safe and well tolerated. Longer term controlled trials are warranted to define the potential efficacy of relaxin in patients with diffuse scleroderma.

Original languageEnglish (US)
Pages (from-to)302-307
Number of pages6
JournalJournal of Rheumatology
Issue number2
StatePublished - Feb 1998


  • Fibrosis
  • Relaxin
  • Systemic sclerosis

ASJC Scopus subject areas

  • Immunology and Allergy
  • Rheumatology
  • Immunology


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