Econazole

The Prestwick Chemical Library, which contains 1,200 small molecules and FDA approved drugs, was acquired at Prestwick Chemicals (Illkirch-Graffenstaden, France). Fluvastatin, simvastatin and atorvastatin were provided by Prestwick Chemicals (Illkirch-Graffenstaden, France). Econazole, miconazole, tioconazole and bifonazole were acquired at Sigma (Sigma-Aldrich, St. Louis, MO, USA).

The majority of the drugs used required individual methods of preparation to ensure that a known concentration was in solution. Econazole (Sigma, UK) was dissolved at 112.43 mM in 1:1 chloroform:methanol solution. This was then diluted in PG media at 1 in 200 to give a stock solution of 562 µM. The preparation of miconazole and sulconazole (all from Sigma, UK) was identical. Drugs were dissolved in DMSO (Sigma, UK), to give a concentration of 208.70 mM for miconazole and 217 mM for sulconazole. These solutions were diluted in PG media to give concentrations of 3.339 mM and 3.472 mM, respectively. Residual drug was solubilised by adjusting the pH with HCl and the final concentration adjusted to 104 µM and 109 µM. Tioconazole (Sigma, UK) was dissolved in DMSO (Sigma, UK) at 500 mM and diluted in PG media to give 16 mM. Residual drug was solubilised by addition of HCL before diluting in PG to give a final concentration of 250 µM. Voriconazole was dissolved in DMSO at 28.63 mM and diluted in PG media to 143 µM. The final formulation of each drug was adjusted where necessary to pH 7.0.

Bifonazole, butoconazole, clotrimazole, econazole, itraconazole, ketoconazole, miconazole, posaconazole, ravuconazole, terconazole, tioconazole, voriconazole and benzyl-4-hydroxybenzoate (Internal Standard, IS) (>98% purity grade), sodium phosphate monobasic and sodium phosphate dibasic (>99% purity grade), phosphoric acid (90% purity grade) and trichloroacetic acid (>99% purity grade) were purchased from Sigma-Aldrich (Milan, Italy).
The commercial drugs were obtained from a local Pharmacy after medical prescription. Both HPLC-grade Acetonitrile (AcN) and methanol (MeOH) were supplied by Carlo Erba (Milan, Italy) and were used without further purification. The water for HPLC analysis was generated by using a Millipore Milli-Q Plus water treatment system (Millipore Bedford Corp., Bedford, MA). Oasis HLB (1 mL, 30 mg) and Sep-Pak (1 mL, 50 mg) were obtained from Waters (Milford, MA), while Strata-X (1 mL, 30 mg) was purchased from Phenomenex (Torrance, CA). MEPS device (syringe) and replacement needle with C₁₈ stationary phase were purchased from SGE Analytical Science (Melbourne, Australia).