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We examined factors associated with virological failure in 310 HIV-infected patients receiving atazanavir (ATV). Independent links were identified with virological failure under ATV: virological failure previous history (P = 0.006) and ATV underdosing (P = 0.04). A maintenance therapy was protective (P = 0.01). The optimal therapeutic ranges of ATV concentration were found to be from 300 ng/ml (or 180 for patients treated with maintenance therapy) to 650 ng/ml for C24 and from 1000 ng/ml (or 500 for patients treated with maintenance therapy) to 2000 ng/ml for C12.

5-Fluorouracil:carnauba wax microspheres were prepared using a meltable dispersion process with the aid of a surfactant as a wetting agent. It was noted that only hydrophilic surfactants were able to wet the 5-fluorouracil and substantially increased its content in the microspheres. No marked effect was observed in the particle size distribution of the solid microspheres as a function of the nature of the surfactant. Increasing the stirring rate in the preparation process decreased, first, the mean droplet size of the emulsified melted dispersion in the vehicle during the heating process, and, consequently, the mean particle size of the solidified microspheres during the cooling process. 5-Fluorouracil cumulative release from the microspheres followed first-order kinetics, as shown by nonlinear regression analysis. Although the kinetic results were not indicative of the true release mechanism from a single microsphere, it was believed that 5-fluorouracil release from the microspheres was probably governed by a dissolution process, rather than by a leaching process through the carnauba wax microspheres.