Novel protease inhibitor-loaded Nanoparticle-in-Microparticle Delivery System leads to a dramatic improvement of the oral pharmacokinetics in dogs.

With the advent of the Highly Active Antiretroviral Therapy, the morbidity and the mortality associated to HIV have been considerably reduced. However, 35-40 million people bear the infection worldwide. One of the main causes of therapeutic failure is the frequent administration of several antiretrovirals that results in low patient compliance and treatment cessation. In this work, we have developed an innovative Nanoparticle-in-Microparticle Delivery System (NiMDS) comprised of pure drug nanocrystals of the potent protease inhibitor indinavir free base (used as poorly water-soluble model protease inhibitor) produced by nanoprecipitation that were encapsulated within mucoadhesive polymeric microparticles. Pure drug nanoparticles and microparticles were thoroughly characterized by diverse complementary techniques. NiMDSs displayed an encapsulation efficiency of approximately 100% and a drug loading capacity of up to 43% w/w. In addition, mucoadhesiveness assays ex vivo conducted with bovine gut showed that film-coated microparticles were retained for more than 6 h. Finally, pharmacokinetics studies in mongrel dogs showed a dramatic 47- and 95-fold increase of the drug oral bioavailability and half-life, respectively, with respect to the free unprocessed drug. These results support the outstanding performance of this platform to reduce the dose and the frequency of administration of protease inhibitors, a crucial step to overcome the current patient-incompliant therapy.

Relationship between P-glycoprotein activity measured in peripheral blood mononuclear cells and indinavir bioavailability in healthy volunteers.

Indinavir, a HIV-1 protease inhibitor, showed large inter-individual pharmacokinetic variability. It has been proposed as a substrate of P-glycoprotein (P-gp), an efflux transporter, that may contribute to limit indinavir bioavailability. A liquid formulation of indinavir was developed from indinavir capsules in order to study indinavir pharmacokinetics in healthy volunteers. Compartmental and noncompartmental analysis of indinavir plasma concentrations showed high inter-individual variability in terms of area under the curve (AUC) and maximal plasma concentration (C(max)). A significant negative association between AUC normalized to body weight (AUC x weight) and lymphocyte P-gp activity, using Rh123 efflux assay, was observed (p = 0.008; r = -0.75). AUC normalized to elimination rate constant (AUC x beta) also showed a significant negative relationship with lymphocyte P-gp activity (p = 0.03, r = -0.64). Apparent clearance (CL/[F x weight]) and volume of distribution (VD/[F x weight]) showed a positive correlation with P-gp activity. Conversely, elimination rate constant did not correlate with P-gp activity. Although there is not enough evidence of a correlation between lymphocitary and intestinal function of P-gp, our results suggest a relationship between a P-gp phenotype marker, Rh123 efflux assay in lymphocytes, and indinavir bioavailability.

Validation of high-performance liquid chromatography methods for determination of zidovudine, stavudine, lamivudine and indinavir in human plasma.

OBJECTIVE: Simple methods for the determination of zidovudine (AZT), stavudine (d4T), lamivudine (3TC) and indinavir (INV) in human plasma by reversed-phase liquid chromatography (HPLC) with UV detection were described and validated. METHOD: Solid-liquid extraction procedures were applied to the samples prior to analysis. Chromatography was performed on a C-18 analytical columns and the retention time ranged from 6.8 to 8.0 min for stavudine, 7.5 to 9.0 min for lamivudine, 11.2 to 11.9 min for zidovudine and indinavir. Four methods were validated for specificity, inter-and intra-assay precision and accuracy, absolute recovery and stability. RESULTS: Analytical curve ranged from 10-1600 ng/ml for stavudine, 50-3200 ng/ml for lamivudine, 0.05-5.0 microg/ml for zidovudine and 0.1-10.0 microg/ml for indinavir. Analytes stability during sampling processing and storage were established. Extraction recoveries are higher than 89% for all formulations. CONCLUSIONS: These methods proved to be simple, accurate and precise, and are currently in use in our laboratory for the quantitative analysis of antiretrovirals products in plasma, and for further pharmacokinetics and bioequivalence studies.

Validation of high-performance liquid chromatography methods for determination of zidovudine, stavudine, lamivudine and indinavir in human plasma

Objetivo: Fueron descritos y validados m¨¦todos anal¨ªticos simplespara la determinaci¨®n de zidovudina (AZT), estavudina (d4T),lamivudina (3TC), e indinavir (INV) en plasma humano por cromatograf¨ªal¨ªquida de alta resoluci¨®n (HPLC) con detecci¨®n UV.M¨¦todo: Se aplic¨® la extracci¨®n en fase s¨®lida para la preparaci¨®nde las muestras previo al an¨¢lisis. La corrida cromatogr¨¢ficase realiz¨® en una columna anal¨ªtica C-18 y el tiempo de retenci¨®nse movi¨® en un rango de 6,8-11,9 min para d4T, 7,5-9,0para 3TC y 11,2-11,9 para AZT e INV. Se validaron 4 m¨¦todosen cuanto a especificidad, precisi¨®n y exactitud entre d¨ªas y en eld¨ªa, as¨ª como recobrado y estabilidad.Resultados: Los rangos de concentraciones de las curvasanal¨ªticas eran de 10-1600 ng/ml para d4T, 50-3200 ng/ml para3TC, 0,05-5,0 ¦Ìg/ml para AZT y 0,1-10,0 ¦Ìg/ml para INV. Sedemostr¨® la estabilidad del analito durante el procesamiento de lasmuestras y el almacenamiento. Para las 4 formulaciones los resultadosdel por ciento de recobrado fue superior al 89%.Conclusiones: Estos m¨¦todos demostraron ser simples, exactos,precisos y son los utilizados actualmente en nuestro laboratoriopara el an¨¢lisis cuantitativo de productos antirretrovirales enplasma, as¨ª como para posteriores estudios de farmacocin¨¦tica ybioequivalencia(AU)

Objective: Simple methods for the determination of zidovudine(AZT), stavudine (d4T), lamivudine (3TC) and indinavir (INV)in human plasma by reversed-phase liquid chromatography(HPLC) with UV detection were described and validated.Method: Solid-liquid extraction procedures were applied tothe samples prior to analysis. Chromatography was performed ona C-18 analytical columns and the retention time ranged from 6.8to 8.0 min for stavudine, 7.5 to 9.0 min for lamivudine, 11.2 to11.9 min for zidovudine and indinavir. Four methods were validatedfor specificity, inter-and intra-assay precision and accuracy,absolute recovery and stability.Results: Analytical curve ranged from 10-1600 ng/ml forstavudine, 50-3200 ng/ml for lamivudine, 0.05-5.0 ¦Ìg/ml forzidovudine and 0.1-10.0 ¦Ìg/ml for indinavir. Analytes stabilityduring sampling processing and storage were established. Extractionrecoveries are higher than 89% for all formulations.Conclusions: These methods proved to be simples, accurateand precise, and are currently in use in our laboratory for thequantitative analysis of antiretrovirals products in plasma, and forfurther pharmacokinetics and bioequivalence studies(AU)