Objetivo. Caracterizar el fenómeno de la resistencia a los diferentes medicamentos antirretrovirales en pacientes en quienes se practicó el estudio de genotipificación en Colombia, durante el período 2000-2007. Diseño. Descriptivo, retrospectivo y basado en el laboratorio. Métodos. Entre los años 2000 y 2007, se obtuvo la secuencia de los genes de la proteasa y transcriptasa inversa del virus de la inmunodeficiencia humana (VIH) de 650 pacientes presuntamente en tratamiento antirretroviral, procedentes de diferentes regiones de Colombia. Las secuencias se procesaron con el programa Geno2pheno resistance, el cual infiere la resistencia a partir de la secuencia. Resultados. El 82,1% de las cepas virales fue resistente a uno o más medicamentos. La frecuencia de resistencia fue mayor para la lamivudina (55,4%), la nevirapina (54,3%) y el efavirenz (52,6%), y más baja para la estavudina (11,0%). El 45,1% fue resistente a la zidovudina. La resistencia a los inhibidores de proteasa osciló entre 30% y 38%. Se observó que la frecuencia de resistencia va en aumento para los inhibidores de la transcriptasa inversa, pero no para los inhibidores de proteasa. Conclusiones. La frecuencia de resistencia fue mayor en los antirretrovirales con una baja barrera genética y en aquéllos cuyo uso se ha incrementado en los últimos años.

Objective. To characterize the resistance to anti-retroviral drugs in patients subject of genotypic sensitivity testing in Colombia during 2000-2007. Design. Descriptive, retrospective, laboratory based. Methods. Between the years 2000 and 2007 the sequences of the HIV protease and transcriptase genes were obtained from 650 patients presumably under antiretroviral treatment throughout the country. The sequences were processed with the program "geno2pheno resistance", which infers the resistance by using the sequences. The results were statistically analyzed. Results. 82.1% of the viral strains were resistant to one or more drugs. The frequency of resistance was higher for lamivudine (55.4%), nevirapine (54.3%), and efavirenz (52.6%), and lower for stavudine (11.0%). 45.1% were resistant to zidovudine. Resistance to protease inhibitors varied between 30% and 38%. We observed that the frequency of resistance is rising for the reverse transcriptase inhibitors but not for the protease inhibitors. Conclusions. The frequency of resistance was higher for the antiretroviral drugs with a lower genetic barrier and for those which use has increased during these last years.

By using the van't Hoff and Gibbs equations the apparent thermodynamic functions Gibbs energy, enthalpy, and entropy of solution for sodium naproxen in ethanol + water cosolvent mixtures, were evaluated from solubility data determined at temperatures from (278.15 to 308.15) K. The drug solubility was greatest in neat water and lowest in neat ethanol at all the temperatures studied. By means of non-linear enthalpy-entropy compensation analysis, it follows that the dissolution process of this drug in ethanol-rich mixtures is entropy-driven, whereas, in water-rich mixtures the process is enthalpy-driven.

An analytical method by liquid chromatography has been proposed and validated to study the apparent solubility of ibuprofen in biorelevant dissolution media. The main properties of the studied media were pH values of 5.0 and 6.5 and the presence or absence of some natural surfactant agents. The parameters evaluated were specificity, linearity, precision, accuracy, and detection and quantification limits, as well as the drug stability under the analysis conditions. The developed method was useful to determine the apparent solubility of this drug as a function of temperature and surfactants concentration to demonstrate the validity of the Biopharmaceutics Classification System.