Formulation and evaluation of liquisolid compacts for olmesartan medoxomil

Liquisolid Technique: A Novel Technique with Remarkable Applications in Pharmaceutics

Recently, it has been observed that newly developed drugs are lipophilic and have low aqueous solubility issues, which results in a lower dissolution rate and bioavailability of the drugs. To overcome these issues, the liquisolid technique, an innovative and advanced approach, comes into play. This technique involves the conversion of the drug into liquid form by dissolving it in non-volatile solvent and then converting the liquid medication into dry, free-flowing, and compressible form by the addition of carrier and coating material. It offers advantages like low cost of production, easy method of preparation, and compactable with thermo labile and hygroscopic drugs. It has been widely applied for BCS II drugs to enhance dissolution profile. Improving bioavailability, providing sustained release, minimizing pH influence on drug dissolution, and improving drug photostability are some of the other promising applications of this technology. This review article presents an overview of the liquisolid technique and its applications in formulation development.

Quality-by-Design-Based Development of Rivaroxaban-Loaded Liquisolid Compact Tablets with Improved Biopharmaceutical Attributes

Rivaroxaban (RXN) finds use in the management of pulmonary embolism and deep vein thrombosis. Its poor solubility (5-7 µg/mL) and P-gp-mediated efflux from intestinal lining limits the oral application of RXN. This work assessed the impact of liquisolid compact technique in augmenting the solubility and bioavailability of RXN. PEG 400, Avicel PH 200, and Aerosil 200 were used as non-volatile liquid, carrier, and coating material, respectively, to formulate RXN liquid-solid compacts (RXN LSCs). A 32-factor factorial design was used in the optimisation to assess the impacts of factors (load factor and carrier:coating ratio) on the responses (angle of repose and Q30 min). Pre-compression parameters of RXN LSCs suggested adequate flow and compressibility. Optimisation data suggested significant influence of factors on both the responses. Optimised RXN LSC-based tablets showed a significantly higher in vitro dissolution rate than RXN API and Xarelto® tablets due to improved solubility, reduced crystallinity, greater surface area, and enhanced wetting of RXN particles. XRD, DSC, and SEM data supported RXN's amorphization. The cytotoxicity (MTT assay) and permeation studies indicated the nontoxicity of prepared RXN LSC tablets and the role of PEG 400 in inhibiting P-gp. Pharmacokinetic study of RXN LSC-based tablets in Albino Wistar rats exhibited 2.51- and 1.66-times higher AUC in comparison to RXN API and Xarelto® tablets respectively, demonstrating that developed formulation had a greater oral bioavailability. The RXN LSC tablets showed longer bleeding times and higher rates of platelet aggregation than RXN API. Thus, RXN LSC tablets can be considered a facile, scalable technology.

The importance of the coating material type and amount in the preparation of liquisolid systems based on magnesium aluminometasilicate carrier

Albeit the preparation of liquisolid systems represents an innovative approach to enhance the dissolution of poorly soluble drugs, their broader utilization is still limited mainly due to the problematic conversion of the liquid into freely flowing and readily compressible powder. Accordingly, the presented study aims to determine the optimal carrier/coating material ratio (R value) for formulations based on magnesium aluminometasilicate (NUS2) loaded with polyethylene glycol 400. Four commercially available colloidal silica were used as coating materials in nine different R values (range of 5 - 100). The obtained results suggested that the higher R value leads to the superior properties of powder mixtures, such as better flowability, as well as compacts with higher tensile strength and lower friability. Moreover, it was observed that the type of coating material impacts the properties of liquisolid systems due to the different arrangement of particles in the liquisolid mixture. To confirm the noted dependency of R value and coating material type, the one- and two-way ANOVA, linear regression and principal component analysis (PCA) techniques were performed. In addition, a comparison of results with the properties of loaded NUS2 itself revealed that LSS with sufficient properties may be prepared even without the coating material.

Design of Olmesartan Medoxomil-Loaded Nanosponges for Hypertension and Lung Cancer Treatments

Olmesartan medoxomil (OLM) is one of the prominent antihypertensive drug that suffers from low aqueous solubility and dissolution rate leading to its low bioavailability. To improve the oral bioavailability of OLM, a delivery system based on ethylcellulose (EC, a biobased polymer) nanosponges (NSs) was developed and evaluated for cytotoxicity against the A549 lung cell lines and antihypertensive potential in a rat model. Four OLM-loaded NSs (ONS1-ONS4) were prepared and fully evaluated in terms of physicochemical properties. Among these formulations, ONS4 was regarded as the optimized formulation with particle size (487 nm), PDI (0.386), zeta potential (ζP = -18.1 mV), entrapment efficiency (EE = 91.2%) and drug loading (DL = 0.88%). In addition, a nanosized porous morphology was detected for this optimized system with NS surface area of about 63.512 m2/g, pore volume and pore radius Dv(r) of 0.149 cc/g and 15.274 Å, respectively, measured by nitrogen adsorption/desorption analysis. The observed morphology plus sustained release rate of OLM caused that the optimized formulation showed higher cytotoxicity against A549 lung cell lines in comparison to the pure OLM. Finally, this system (ONS4) reduced the systolic blood pressure (SBP) significantly (p < 0.01) as compared to control and pure OLM drug in spontaneously hypertensive rats. Overall, this study provides a scientific basis for future studies on the encapsulation efficiency of NSs as promising drug carriers for overcoming pharmacokinetic limitations.

Solubility determination and solution thermodynamics of olmesartan medoxomil in (PEG-400 + water) cosolvent mixtures

The solubility and solution thermodynamic properties of a weakly water-soluble compound olmesartan medoxomil (OLM) in binary 'polyethylene glycol (PEG-400) + water' cosolvent compositions were determined. The 'mole fraction solubility (x _e)' of OLM in binary 'PEG-400 + water' cosolvent compositions and pure solvents (PEG-400 and water) was determined at 'T = 295.15-330.15 K' and 'p = 0.1 MPa'. The Hansen solubility parameter (HSP) of OLM, pure PEG-400, pure water, and binary 'PEG-400 + water' cosolvent compositions free of OLM were also predicted. The obtained x _e values of OLM were correlated using 'van't Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-van't Hoff' computational models with the error values of <4.0%. The maximum and minimum x _e value of OLM was predicted in neat PEG-400 (1.15 × 10^-2 at T = 330.15 K) and neat water (1.90 × 10^-7 at T = 295.15 K), respectively. The OLM HSP was predicted to be more close with that of neat PEG-400. The x _e value of OLM was found increased significantly with increase in temperature and PEG-400 mass fraction in all 'PEG-400 + water' cosolvent compositions including neat PEG-400 and neat water. An 'apparent thermodynamic analysis' studies presented an 'endothermic and entropy-driven dissolution' of OLM in all 'PEG-400 + water' cosolvent compositions including pure PEG-400 and pure water.

Systematic Development of Bicalutamide Immediate Release Pellets Using Aeroperl and Non-MCC Extruder Aid

Background:

The Microcrystalline Cellulose is called as a gold standard for the manufacture of pellets. The poor disintegration leads to incomplete drug release that restricts the use of MCC in the immediate-release formulation.

Objective:

The present work aims to explore non-MCC extruder aid for pellet formulation and solubility modulation potential of Aeroperl® 300 Pharma.

Methods:

Bicalutamide (BCL) was selected as a model BCS class-II drug. The solubility of BCL was assessed in different vehicles such as polyethylene glycol, propylene glycol, and Tween by carrying out phase solubility study. The suitable vehicle was selected based on the higher solubility of BCL. The vehicle was further adsorbed on newer adsorbent Aeroperl® 300 Pharma to formulate liquisolid granules. The liquisolid granules were further incorporated into the pellet using mannitol and microcrystalline cellulose as an extruder aid. Box-Behnken design was adopted for the optimization of formulation considering MCC: mannitol ratio, the concentration of HPMC and spheronizer speed as independent factors whereas drug release at 30 min, disintegration time and aspect ratio were selected as dependent variables. The pellets were evaluated for different evaluation parameters.

Results:

Propylene glycol was selected for the formulation of liquisolid technique based on the results of the phase solubility study. Propylene glycol containing BCL was adsorbed on Aeroperl 300 Pharma. The optimized batch was selected exploring the Design-Expert software by considering the limits of different responses. Pellet had excellent flowability. Friability was found to be within the range (<1%). Pellets were found to be spherical and had pores on the surfaces.

Conclusion:

Liquisolid granules containing newer solubilizer Aeroperl was found to be a promising approach for the improvement in the solubility of the drug. The use of mannitol with MCC has a profound effect on disintegration time, without altering flow property and other parameters. No patents were reported on the combination of Bicalutamide, mannitol and Aeroperl. The critical finding of the present work is to use mannitol as an extruder aid to fasten the disintegration leads to complete drug release within a short period of time. Aeroperl and Mannitol, MCC: mannitol ratio, the concentration of HPMC and spheronizer speed were found to be significant and had the potential effect in pellet formulation.

Bioavailability Enhancement of Olmesartan Medoxomil Using Hot-Melt Extrusion: In-Silico, In-Vitro, and In-Vivo Evaluation

Olmesartan medoxomil (OLM) an antihypertensive molecule with poor solubility and poor bioavailability (26% when taken orally) was selected as a model drug. Herein, rationale development of amorphous solid dispersion with hot-melt extrusion of poorly bioavailable OLM was carried out with the aid of quality by design (QbD), in-silico, in-vitro, and in-vivo evaluations. Polymer selection commenced with the selection of thermoplastic water-soluble polymers with the compatible processing temperature window as per the thermal behavior of OLM. Molecular dynamics (MD) simulations as well assisted in the selection of a carrier. Promising dissolution enhancement was observed with the help of Kollidon VA-64 (VA-64) as a carrier. Optimization of the formulation was executed using the QbD approach with design of experiment as a statistical optimization tool. Interactions between VA-64 and OLM on the atomic level were studied with the help of atomistic MD simulations. Characterization of the optimized extrudates were carried out with scanning electron microscopy, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Fourier transforms infrared spectroscopy, powder X-ray diffraction, in-vitro dissolution study, and in-vivo pharmacokinetic studies. Molecular-level mixing of OLM with VA-64 resulted into glass solution formation which rapidly dissolves (28 times in-vitro dissolution enhancement) in GI tract fluids and instantly gets absorbed into blood circulation. In-vivo pharmacokinetic studies performed in Sprague-Dawley rats reflected superior bioavailability (201.60%) with a significant increase in the C_max with short T_max through amorphization of OLM. The in-silico results were in agreement with the observed results of in-vitro dissolution studies and in-vivo pharmacokinetic study.

Inhibition of Co-Crystallization of Olmesartan Medoxomil and Hydrochlorothiazide for Enhanced Dissolution Rate in Their Fixed Dose Combination

Olmesartan medoxomil (Olm) and hydrochlorothiazide (HCTZ) are fixed dose combination (FDC) for treatment of hypertension. They have hydrogen bonding sites and may interact during co-processing. The consequences of such interaction are not clear. This study investigated the possibility of this interaction during co-processing. The research was extended to inhibit deleterious interactions. The drugs were co-evaporated from ethanolic solution to maximize the chance of interaction. This was performed in the absence and presence of hydroxypropyl methylcellulose (HPMC) and/or aerosil. The products were characterized using Fourier transform infrared spectroscopy (FTIR), differential thermal analysis, and powder X-ray diffraction (PXRD) in addition to dissolution studies. Co-evaporation of Olm with HCTZ in the absence of excipients produced crystalline material with FTIR spectrum showing intermolecular hydrogen bonding. This material showed thermal pattern of new crystalline species. This was identified as Olm/HCTZ co-crystal by PXRD. This co-crystallization reduced the dissolution rate of both drugs. This co-crystallization was inhibited in the presence of HPMC, but the dissolution rate was not significantly enhanced accordingly. Co-processing in the presence of both HPMC and aerosil eliminated the co-crystallization and minimized the intermolecular drug-drug interaction with subsequent dissolution enhancement. The study introduced a composition for fixed dose combination of Olm and HCTZ with enhanced dissolution.

Pharmaceutical Dispersion Techniques for Dissolution and Bioavailability Enhancement of Poorly Water-Soluble Drugs

Over the past decades, a large number of drugs as well as drug candidates with poor dissolution characteristics have been witnessed, which invokes great interest in enabling formulation of these active ingredients. Poorly water-soluble drugs, especially biopharmaceutical classification system (BCS) II ones, are preferably designed as oral dosage forms if the dissolution limit can be broken through. Minimizing a drug’s size is an effective means to increase its dissolution and hence the bioavailability, which can be achieved by specialized dispersion techniques. This article reviews the most commonly used dispersion techniques for pharmaceutical processing that can practically enhance the dissolution and bioavailability of poorly water-soluble drugs. Major interests focus on solid dispersion, lipid-based dispersion (nanoencapsulation), and liquisolid dispersion (drug solubilized in a non-volatile solvent and dispersed in suitable solid excipients for tableting or capsulizing), covering the formulation development, preparative technique and potential applications for oral drug delivery. Otherwise, some other techniques that can increase the dispersibility of a drug such as co-precipitation, concomitant crystallization and inclusion complexation are also discussed. Various dispersion techniques provide a productive platform for addressing the formulation challenge of poorly water-soluble drugs. Solid dispersion and liquisolid dispersion are most likely to be successful in developing oral dosage forms. Lipid-based dispersion represents a promising approach to surmounting the bioavailability of low-permeable drugs, though the technique needs to traverse the obstacle from liquid to solid transformation. Novel dispersion techniques are highly encouraged to develop for formulation of poorly water-soluble drugs.

Olmesartan

Olmesartan is an angiotensin receptor blockers with actions similar to those of losartan; it is used for the treatment of high blood pressure by relaxing blood vessels for this reason blood can flow more easily. It could be used alone or in combination with other antihypertensive drugs. This chapter gives a comprehensive profile of olmesartan, containing detailed nomenclature, formulae, elemental analysis, and appearance of the drug. In addition this chapter also describes several methods of synthesis and usage of the olmesartan. The profile covers the physicochemical properties including pK_a value, solubility, X-ray powder diffraction, melting point, and procedures of analysis (compendial, spectroscopic, electrochemical, and chromatographic techniques of analysis). Comprehensive pharmacology is also presented (pharmacological actions, therapeutic uses and dosing, interactions, and adverse effects and precautions). Eighty references were given as a proof of the above-mentioned studies.

Modern evaluation of liquisolid systems with varying amounts of liquid phase prepared using two different methods

Liquisolid systems are an innovative dosage form used for enhancing dissolution rate and improving in vivo bioavailability of poorly soluble drugs. These formulations require specific evaluation methods for their quality assurance (e.g., evaluation of angle of slide, contact angle, or water absorption ratio). The presented study is focused on the preparation, modern in vitro testing, and evaluation of differences of liquisolid systems containing varying amounts of a drug in liquid state (polyethylene glycol 400 solution of rosuvastatin) in relation to an aluminometasilicate carrier (Neusilin US2). Liquisolid powders used for the formulation of final tablets were prepared using two different methods: simple blending and spraying of drug solution onto a carrier in fluid bed equipment. The obtained results imply that the amount of liquid phase in relation to carrier material had an effect on the hardness, friability, and disintegration of tablets, as well as their height. The use of spraying technique enhanced flow properties of the prepared mixtures, increased hardness values, decreased friability, and improved homogeneity of the final dosage form.