Influence of atazanavir on the pharmacodynamics and pharmacokinetics of gliclazide in animal models

In situ gastric floating gel of atazanavir sulphate for sustained release: formulation, optimization and evaluation

Aim: Atazanavir sulphate belongs to BCS class II drug, its oral bioavailability is limited due to its rapid first-pass metabolism and P-gp efflux. Materials & methods: The in situ floating gel using the complexed drug was prepared by ion gelation method and optimized the formulation as per 32 full factorial design. Results: Floating lag time of optimized formulation was found to be 18 s and percentage drug release of 94.18 ± 0.18 % at the end of 16 h. The concentration of gelling polymer affects drug release and a floating lag time and vice versa. Conclusion: In situ floating gel of atazanavir sulphate was found promising to sustain drug release due to an increased gastric residence time, which leads to enhanced potential therapy.

Interaction of two peptide drugs with biomacromolecules analyzed by molecular docking and multi-spectroscopic methods

Peptide drugs, which are mainly used for the treatment of AIDS, myeloma, and breast cancer, have evolved rapidly owing to their high efficacy and low side effects. The interaction mechanisms of two peptide drugs with two biological macromolecules (protein and DNA), which are of great significance in disease prevention and drug design, were investigated using molecular docking, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, UV-visible spectroscopy and viscosity measurements. The interaction between a series of common drugs and ovalbumin (OVA) was simulated by molecular docking, and two peptide drugs with the highest energy values, namely atazanavir and carfilzomib, were selected; the binding energy values of these drugs with OVA were -59.20 and -55.93 kcal/mol, respectively. The K_b values of the interaction of the two drugs with OVA/DNA were in the range of 10⁴-10⁷ M^-1, and the binding affinity of the drugs was stronger with OVA than with DNA. Hydrogen bonds and van der Waals forces were very important for the binding between drugs and OVA through molecular docking studies, and it was consistent with experimental results (ΔH < 0, ΔH < 0). The synchronous fluorescence spectrum showed that the interaction caused a change to the original structure of OVA, and atazanavir had a greater effect on OVA than carfilzomib. CD spectrum analysis also demonstrated that the conformation of OVA changed slightly. The interaction between atazanavir and DNA was mainly driven by hydrophobic forces (ΔH > 0 and ΔH > 0), whereas the major interaction forces involved in the binding of carfilzomib with DNA were hydrogen bonds and van der Waals forces. DNA melting studies, UV-visible spectroscopy, CD spectroscopy and viscosity measurements established that the interaction between the drugs and DNA was groove binding.

UV-Vis, FTIR, 1H, 13C NMR spectra and thermal studies of charge transfer complexes formed in the reaction of Gliclazide with π- and σ-electron acceptors

Charge transfer interactions (CT) between a gliclazide (GLC) donor and a picric acid (PA) π acceptor or iodine σ acceptor, were studied in a chloroform solution and in the solid state. UV-vis spectroscopy elucidated the formation of the complexes, and allowed determination of the stoichiometry, stability constants (K), and thermodynamic quantities (ΔG°, ΔH°, and ΔS°), and spectroscopic properties such as the molar extinction coefficient (ε_CT), oscillator strength (f), transition dipole moment (μ_EN), and ionization potential (I_p). Beer's law was obeyed over the 2-8 and 4-12 μg mL^-1 concentration ranges for GLC with PA (method A) and I₂ (method B), respectively, with correlation coefficients of 0.9986 and 0.9989. The limits of detection (LOD) and limits of quantification (LOQ) have also been reported. The 1:1 stoichiometric CT complexes were synthesized and characterized by FTIR, ¹H, and ¹³C NMR spectroscopy. The results indicated a favorable proton migration from PA to the donor molecule, and an interaction between the NH of GLC and iodine. Thermogravimetric analysis techniques (TGA/DTA) and differential scanning calorimetry (DSC) were used to determine the thermal stability of the synthesized CT complex. The kinetic parameters (ΔG*, ΔH*, and ΔS*) were calculated from thermal decomposition data using the Coats-Redfern method.

Population pharmacokinetics of gliclazide in normal and diabetic rabbits

Gliclazide is a second-generation sulphonylurea drug widely used in the treatment of type 2 diabetes. However, there is no single report to describe the population pharmacokinetics of gliclazide in animal models. This study was aimed to evaluate the population pharmacokinetics (PK) of gliclazide in normal and alloxan-induced diabetic rabbits using nonlinear mixed effects modeling. A total of 90 New Zealand white rabbits were administered with three doses (4.13, 8.27 and 16.53 mg/kg b.wt) of gliclazide by an oral route. Blood samples were collected up to 24 hr and the gliclazide concentrations in rabbit were determined using the HPLC method. The non-compartmental and classical compartmental PK analyses were performed using Phoenix WinNonlin. Population PK analysis of gliclazide was performed using nonlinear mixed-effects model software NONMEM and Phoenix NLME considering the weight, age, sex, health and dose as covariates. The final population values for clearance (CL), volume of distribution (V) and the absorption rate constant (k_a ) were 5270 ml/hr, 55700 ml and 0.708 hr^-1 , respectively. The inter-individual variability in gliclazide CL, V and k_a was 16.3%, 14.9% and 26.5%, respectively. There was no significant difference between NONMEM and Phoenix NLME pharmacokinetic results. The visual predictive check and bootstrap analysis confirmed the predictive ability, model stability and precision of the parameter estimates from this model. This population PK model demonstrated that gliclazide pharmacokinetics is best described by one-compartment model with first-order absorption in rabbits. Body weight is a covariate that significantly influences gliclazide kinetic disposition in rabbits.

Atazanavir-loaded Eudragit RL 100 nanoparticles to improve oral bioavailability: optimization and in vitro/in vivo appraisal

Atazanavir (ATV) is a HIV protease inhibitor. Due to its intense lipophilicity, the oral delivery of ATV encounters several problems such as poor aqueous solubility, pH-dependent dissolution, rapid first-pass metabolism in liver by CYP3A5, which result in low bioavailability. To overcome afore mentioned limitations, ATV-loaded Eudragit RL100 nanoparticles (ATV NPs) were prepared to enhance oral bioavailability. ATV NPs were prepared by nanoprecipitation method. The ATV NPs were systematically optimized (OPT) using 3(2) central composite design (CCD) and the OPT formulation located using overlay plot. The pharmacokinetic study of OPT formulation was investigated in male Wistar rats, and in-vitro/in-vivo correlation level was established. Intestinal permeability of OPT formulation was determined using in situ single pass perfusion (SPIP) technique. Transmission electron microscopy studies on OPT formulation demonstrated uniform shape and size of particles. Augmentation in the values of Ka (2.35-fold) and AUC0-24 (2.91-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT formulation compared to pure drug. Successful establishment of in vitro/in vivo correlation (IVIVC) Level A substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions. In situ SPIP studies ascribed the significant enhancement in absorptivity and permeability parameters of OPT formulation transport through the Peyer's patches. The studies, therefore, indicate the successful formulation development of NPs with distinctly improved bioavailability potential and can be used as drug carrier for sustained or prolonged drug release.

Effect of antiretroviral drugs on the pharmacodynamics of gliclazide with respect to glucose-insulin homeostasis in animal models

The objective of this study was to investigate the effect of oral administration of antiretroviral drugs (indinavir, ritonavir, atazanavir, efavirenz and nevirapine) on the pharmacodynamics of gliclazide in rats (normal and diabetic) and rabbits with respect to glucose-insulin homeostasis to evaluate the safety and effectiveness of the combinations. Blood samples were collected at regular time intervals in rats from retro orbital puncture and by marginal ear vein puncture in rabbits. All the blood samples were analyzed for blood glucose by glucose oxidase-peroxidase method and insulin by a radio immuno assay method. The insulin resistance index and β-cell function were determined by a homeostasis model assessment. Indinavir and ritonavir alone had significant impact on glucose-insulin homeostasis in animal models among the antiretroviral drugs used in our study. In combination, indinavir and efavirenz significantly reduced the activity of gliclazide, while ritonavir and atazanavir significantly increased the activity of gliclazide. However, nevirapine had no significant effect on the activity of gliclazide. From this study we conclude that glucose-insulin homeostasis disorders associated with antiretroviral drugs are not class-specific, but are drug-specific. So care should be taken when indinavir, ritonavir, atazanavir and efavirenz are prescribed for diabetic patients.