Bioequivalence and Bioavailability Forum

Hi Irene,

❝ Have anyone here ever conducted Bioequivalence study of Sulfasalazine?

Yes. My results (T₁: 1×4 500 mg IR, T₂: 1×4 500 mg enteric coated, R: 2,000 mg suspension, six-sequence Williams’ design, sampling for 60 hours, washout two weeks, 24 eligible subjects, plasma and urine). This study was performed for the originator. Both test products showed lower bioavailabilities of sulfasalazine and 5-ASA, whereas sulfapyridine and N-acetylsulfapyridine were BE. CVs for plasma:

• Sulfasalazine
  • C_max: 44.9%
    AUC_0–t: 44.6%
• 5-Aminosalicylic Acid
  • C_max: 46.8%
    AUC_0–t: 45.8%
• Sulfapyridine
  • C_max: 12.7%
    AUC_0–t: 12.6%
• N-Acetylsulfapyridine
  • C_max: 7.42%
    AUC_0–t: 7.95%

Given the high variabilities of Sulfasalazine and 5-ASA I suggest reference-scaling.