Tablet Formulation Studies on Recrystallized Active Pharmaceutical Ingredients of Valsartan and Olmesartan Medoxomil

Both the Valsartan (VAL) and Olmesartan medoxomil (OLM) are widely prescribed anti-hypertensive agents with angiotensin II type I receptor antagonistic activity. Both VAL and OLM are type of BCS class II drugs and having a low and variable oral bioavailability. Recrystallization of VAL and OLM from different organic solvents improved its aqueous solubility and thereby in vitro dissolution properties. In the present investigation, tablets containing Valsartan (VAL), Olmesartan medoxomil (OLM and) recrystallized products were prepared by direct compression method and evaluated for drug content, uniformity of weight, hardness, friability, disintegration time and dissolution properties. All the tablets fulfilled the compendial requirements with regarding to weight variation, friability and disintegration time etc for immediate release tablets. The DP15 (drug percent dissolved at 15 min) values for V-1 (tablets of VAL), V-4 (tablets of methanol recrystallized product with crospovidone as disintegrant) and DIOVAN™ 40mg tablet formulations are 45.97, 98.95 and 82.65 respectively and V-4 formulation showed higher dissolution rate when compared to other formulations. The DP15 values of O-1(tablets of OLM), O-4 (tablets of acetonitrile recrystallized product with crospovidone as disintegrant and OLMY™ (20mg) tablet formulations are 29.25, 99.93 and 84.82 respectively. O-4 tablet formulations showed higher dissolution rate when compared to other tablet formulations. Keywords: Valsartan, Olmesartan medoxomil, Recrystallization, Aqueous solubility

Formulation and evaluation of oral disintegrating tablets of furosemide

Orally disintegrating tablets of Furosemide were prepared, evaluated and the comparison of the action of different concentrations of disintegrants on disintegration and dissolution of the tablets were studied. Direct compression method was used to prepare the orally disintegrating tablets containing 20 mg of Furosemide. The formulation was conducted using different concentrations of crospovidone, croscarmellose and sodium starch glycolate as superdisintegrants and their interactions with Furosemide were also evaluated using FTIR. FTIR studies using the drug and its mixtures with the excipients showed that the peaks correlate with one another which signify that there is no interaction between the drug molecule and the excipients used. The obtained results revealed that the disintegration time of ODTs were between 9 to 59 seconds. The percentage drug content of tablets in all the formulations was found between 91.51% to 106.69%, which complies with the limits established in pharmacopoeia. The in-vitro dissolution studies show maximum release of 89.47% in formulation F3 and minimum of 77.64% in formulation F12. Higher concentration of crospovidone and croscarmellose in formulations F3 and F6 showed better dissolution properties than SSG. So by varying the concentrations of superdisintegrants, oral disintegrating tablets can be formulated.

Effect of Recrystallization Technique on Oral Bioavailability of Valsartan

Valsartan (VAL) is a widely prescribed anti-hypertensive agent with angiotensin II type I receptor antagonistic activity. VAL belongs to BCS class II having a low and variable oral bioavailability (10-35%) and its absorption is dissolution rate limited. Recrystallization of VAL from different organic solvents improved VAL aqueous solubility and thereby in vitro dissolution properties. In this investigation in vivo oral bioavailability (BA) of VAL and its recrystallized products with methanol and ethanol (VMET and VETH respectively) solvents was evaluated in male Wistar rats. Also, a rapid, economical and reliable RP-HPLC-PDA method was developed for the estimation of VAL in rat plasma samples and validated according to ICH guidelines. Chromatographic separation was achieved on an Agilent eclipse C18 column (150×4.6mm, 5µ) with a mobile phase composition of 10mM ammonium acetate: acetonitrile (75:25%v/v) at a flow rate of 1.2 mL/min. The retention time of VAL was found to be 2.9 min and showed good linearity (R2>0.996) in the selected concentration range of 0.5-25µg/mL. A 2.9, 2.8 folds increase in Cmax and a relative bioavailability of 320, 305% was observed with VMET and VETH respectively, when compared to that of untreated VAL. Thus it can be inferred that recrystallization is easy and economical technique for enhancing the pharmaceutical properties like solubility, dissolution properties and oral BA of poorly water soluble drugs like VAL. Keywords: Bioanalytical method, Bioavailability, Male Wistar rats, Valsartan, Recrystallization

Synthesis, Characterization, and Intrinsic Dissolution Studies of Drug–Drug Eutectic Solid Forms of Metformin Hydrochloride and Thiazide Diuretics

The mechanochemical synthesis of drug–drug solid forms containing metformin hydrochloride (MET·HCl) and thiazide diuretics hydrochlorothiazide (HTZ) or chlorothiazide (CTZ) is reported. Characterization of these new systems indicates formation of binary eutectic conglomerates, i.e., drug–drug eutectic solids (DDESs). Further analysis by construction of binary diagrams (DSC screening) exhibited the characteristic V-shaped form indicating formation of DDESs in both cases. These new DDESs were further characterized by different techniques, including thermal analysis (DSC), solid state NMR spectroscopy (SSNMR), powder X-ray diffraction (PXRD) and scanning electron microscopy–energy dispersive X-ray spectroscopy analysis (SEM–EDS). In addition, intrinsic dissolution rate experiments and solubility assays were performed. In the case of MET·HCl-HTZ (χMET·HCl = 0.66), we observed a slight enhancement in the dissolution properties compared with pure HTZ (1.21-fold). The same analysis for the solid forms of MET·HCl-CTZ (χMET·HCl = 0.33 and 0.5) showed an enhancement in the dissolved amount of CTZ accompanied by a slight improvement in solubility. From these dissolution profiles and saturation solubility studies and by comparing the thermodynamic parameters (ΔHfus and ΔSfus) of the pure drugs with these new solid forms, it can be observed that there was a limited modification in these properties, not modifying the free energy of the solution (ΔG) and thus not allowing an improvement in the dissolution and solubility properties of these solid forms.

Integrating Elastic Tensor and PC-SAFT Modeling with Systems-Based Pharma 4.0 Simulation, to Predict Process Operations and Product Specifications of Ternary Nanocrystalline Suspensions

Comminution of BCS II APIs below the 1 μm threshold followed by solidification of the obtained nanosuspensions improves their dissolution properties. The breakage process reveals new crystal faces, thus creating altered crystal habits of improved wettability, facilitated by the adsorption of stabilizing polymers. However, process-induced transformations remain unpredictable, mirroring the current limitations of our atomistic level of understanding. Moreover, conventional equations of estimating dissolution, such as Noyes–Whitney and Nernst–Brunner, are not suitable to quantify the solubility enhancement due to the nanoparticle formation; hence, neither the complex stabilizer contribution nor the adsorption influence on the interfacial tension occurring between the water and APIs is accounted for. For such ternary mixtures, no numeric method exists to correlate the mechanical properties with the interfacial energy, capable of informing the key process parameters and the thermodynamic stability assessment of nanosuspensions. In this work, an elastic tensor analysis was performed to quantify the API stability during process implementation. Moreover, a novel thermodynamic model, described by the stabilizer-coated nanoparticle Gibbs energy anisotropic minimization, was structured to predict the material’s system solubility quantified by the application of PC-SAFT modeling. Comprehensively merging elastic tensor and PC-SAFT analysis into the systems-based Pharma 4.0 algorithm provided a validated, multi-level, built-in method capable of predicting the critical material quality attributes and corresponding key process parameters.

Development, Evaluation, and Molecular Docking of Oral Dissolving Film of Atenolol

The development of oral dissolving film (ODF) of atenolol is an attempt to enhance convenience and compliance for geriatric patients suffering from hypertension. Film former is the most essential component in ODF that determines the physical characteristic and drug release. In this study, three different types of film former including HPMC E5 4% (w/v), 5% (w/v), CMC-Na 3% (w/v), 4% (w/v), and Na-alginate 2.5% (w/v), 3% (w/v) were optimized in Formula 1 (F1) to Formula 6 (F6), respectively. A solvent casting method was employed to develop ODF of atenolol. The films formed by HPMC E5 produced a smooth and flexible surface, whereas CMC-Na and Na-alginate produced gritty textured films. Satisfactory results were obtained from several physical parameters such as film thickness, folding endurance, swelling index, and disintegration time. The homogeneity, drug content, and dissolution properties of ODF with HPMC exhibited better characteristics than the other formulas. Formula 1 exhibited the highest drug release compared to the other ODFs. The molecular docking results showed that there was a hydrogen bonding between atenolol and film formers which was also supported by the FTIR spectrum. The findings of this study suggest that HPMC E5 is the most favorable film former for ODF of atenolol.

Effect of SiC Particle Contents and Size on the Microstructure and Dissolution of SiC-Hydroxyapatite Coatings

Carbon/carbon composites, when used as bone implant materials, do not adhere well to the bone tissues because of their non-bioactive characteristics. Therefore, we electro-deposited SiC-hydroxyapatite coatings (with an ultrasound-assisted step) on carbon/carbon composites. We analyzed how the content and size of the SiC particles affected the structure, morphology, bonding strength and dissolution of the SiC-hydroxyapatite coatings. The hydroxyapatite coating dissolution properties were assessed by the released Ca2+ and the weight loss. The SiC-hydroxyapatite coating on naked carbon/carbon composites showed a more compact microstructure in comparison to the hydroxyapatite coating on carbon/carbon composites. The reasons for the changes in the microstructure and the improvement in the adhesion of the coatings on C/C were discussed. Moreover, the addition of SiC particles increased the binding strengths of the hydroxyapatite coating on C/C composite, as well as reduced the dissolution rate of the hydroxyapatite coating.

Co-Crystals of Resveratrol and Polydatin with L-Proline: Crystal Structures, Dissolution Properties, and In Vitro Cytotoxicities

Resveratrol (RSV) and polydatin (PD) have been widely used to treat several chronic diseases, such as atherosclerosis, pulmonary fibrosis, and diabetes, among several others. However, their low solubility hinders their further applications. In this work, we show that the solubility of PD can be boosted via its co-crystallization with L-proline (L-Pro). Two different phases of co-crystals, namely the RSV-L-Pro (RSV:L-Pro = 1:2) and PD-L-Pro (PD:L-Pro = 1: 3), have been prepared and characterized. As compared to the pristine RSV and PD, the solubility and dissolution rates of PD-L-Pro in water (pH 7.0) exhibited a 15.8% increase, whereas those of RSV-L-Pro exhibited a 13.8% decrease. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of pristine RSV, PD, RSV-L-Pro, and PD-L-Pro against lung cancer cell line A549 and human embryonic kidney cell line HEK-293 indicated that both compounds showed obvious cytotoxicity against A549, but significantly reduced cytotoxicity against HEK-293, with PD/PD-L-Pro further exhibiting better biological safety than that of RSV/RSV-L-Pro. This work demonstrated that the readily available and biocompatible L-Pro can be a promising adjuvant to optimize the physical and chemical properties of RSV and PD to improve their pharmacokinetics.