Background: Cyclosporine A (CyA) is a drug for moderate-to-severe psoriasis. Recently, a generic formulation has been approved as bioequivalent to the branded one. The guidelines for the bioequivalence for critical-dose drugs with a narrow therapeutic range, such as CyA, are questionable. Therefore, it is important to assess the clinical outcome and the pharmacokinetics of different formulations in various patient groups. The current literature lacks of this information in dermatology. The primary objective of this prospective study is to investigate the clinical equivalence (in terms of maintenance of clinical effect) between the generic formulation of CyA and its branded one in patients with psoriasis. A secondary objective is to analyze their trough (C<inf>0</inf>) and peak levels (C<inf>2</inf>).
Methods: Twenty patients with stable psoriasis under treatment with the branded CyA were monitored in terms of clinical efficacy (psoriasis area severity index, PASI), safety (laboratory values), and their pharmacokinetics utilizing trough (C<inf>0</inf>) and peak plasma concentration (C<inf>2</inf>). The same patients were subsequently shifted to the generic formulation for comparison.
Results: In our sample the efficacy of the two formulations was equal in most cases (P=0.863). A non-significant difference between the C<inf>0</inf> and C<inf>2</inf> of the branded CyA compared to the generic one emerged (respectively P=0.738 and P=0.695).
Conclusions: The branded and the generic formulations of CyA seem to be not only bioequivalent, but also comparable in terms of clinical efficacy in patients with psoriasis. However, larger samples are required to confirm these findings.