Mycophenolate mofetil in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis: a prospective pharmacokinetics and clinical study

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) treatment strategy is based on immunosuppressive agents. Little information is available concerning mycophenolic acid (MPA) and the area under the curve (AUC) in patients treated for AAV. We evaluated the variations in pharmacokinetics for MPA in patients with AAV and the relationship between MPA-AUC and markers of the disease. MPA blood concentrations were measured through the enzyme-multiplied immunotechnique (C(0), C(30), C(1), C(2), C(3), C(4), C(6) and C(9)) to determine the AUC. Eighteen patients were included in the study. The median (range) MPA AUC(0-12) was 50·55 (30·9-105·4) mg/h/l. The highest coefficient of determination between MPA AUC and single concentrations was observed with C(3) (P < 0·0001) and C(2) (P < 0·0001) and with C(4) (P < 0·0005) or C(0) (P < 0·001). Using linear regression, the best estimation of MPA AUC was provided by a model including C(30), C(2) and C(4): AUC = 8·5 + 0·77 C(30) + 4·0 C(2) + 1·7 C(4) (P < 0·0001). Moreover, there was a significant relationship between MPA AUC(0-12) and lymphocyte count (P < 0·01), especially CD19 (P < 0·005), CD8 (P < 0·05) and CD56 (P < 0·05). Our results confirm the interindividual variability of MPA AUC in patients treated with MMF in AAV and support a personalized therapy according to blood levels of MPA.

Hydrophylic surfactant-imidazole derivative association studied by RPLC using a hydroorganic solution

A high-performance liquid chromatographic (HPLC) method for an association study of imidazole derivatives in surfactant micellars using a hydrophilic detergent, i.e. Montanox DF 80 was presented. The thermodynamic results obtained showed that imidazole association in the surfactant micelles was effective over a concentration of surfactant equal to approximatively 4 x 10(-4) mol/l. In addition, an enthalpy-entropy compensation study revealed that the type of interaction between the solute and the RP18 stationary phase was independent of the molecular structure. The thermodynamic variations observed were considered to be the result of equilibrium displacement between the solute and free ethanol (respectively free surfactant) and its clusters (respectively to micelles) created in the mobile phase.