Amorphous solid dispersion with increased gastric solubility in tandem with oral disintegrating tablets: a successful approach to improve the bioavailability of atorvastatin

Preformulation study for the selection of a suitable polymer for the development of ellagic acid-based solid dispersion using hot-melt extrusion

Ellagic acid is one of the most studied polyphenolic compounds due to its numerous promising therapeutic properties. However, this therapeutic potential remains difficult to exploit owing to its low solubility and low permeability, resulting in low oral bioavailability. In order to allow an effective therapeutic application of EA, it is therefore necessary to develop strategies that sufficiently enhance its solubility, dissolution rate and bioavailability. For this purpose, solid dispersions based on pre-selected polymers such as Eudragit® EPO, Soluplus® and Kollidon® VA 64, with 5% w/w ellagic acid loading were prepared by hot extrusion and characterized by X-ray diffraction, FTIR spectroscopy and in vitro dissolution tests in order to select the most suitable polymer for future investigations. The results showed that Eudragit® EPO was the most promising polymer for ellagic acid solid dispersions development because its extrudates allowed to obtain a solution supersaturated in ellagic acid that was stable for at least 90 min. Moreover, the resulting apparent solubility was 20 times higher than the actual solubility of ellagic acid. The extrudates also showed a high dissolution rate of ellagic acid (96.25% in 15 min), compared to the corresponding physical mixture (6.52% in 15 min) or the pure drug (1.56% in 15 min). Furthermore, increasing the loading rate of ellagic acid up to 12% in extrudates based on this polymer did not negatively influence its release profile through dissolution tests.

Nanocrystallization Improves the Solubilization and Cytotoxic Effect of a Poly (ADP-Ribose)-Polymerase-I Inhibitor

Olaparib (OLA) is an anticancer agent that acts by inhibiting the poly (ADP-ribose)-polymerase-I (PARP-I). Due to its low solubility and low permeability, it has been placed as a BCS Class-IV drug and hence its clinical use is limited. In this study, we develop the nanocrystals of OLA as a way to improve its solubility and other performances. The OLA-NCs were prepared by antisolvent precipitation method through homogenization and probe sonication technique using a novel amphiphilic polymeric stabilizer (Soluplus®). Particle characterization resulted approximately 103.13 nm, polydispersity-index was 0.104 with positive zeta-potential of +8.67 mV. The crystal morphology by SEM of OLA-NCs (with and without mannitol) exhibited nano-crystalline prism-like structures as compared to the elongated OLA-pure. The DSC, XRD and FTIR were performed to check the interaction of Soluplus, mannitol and OLA did not exhibit any physical interaction among the OLA, Soluplus® and mannitol that is indicated by the presence of parent wave number peak. Two-fold increased solubility of OLA was found in PBS with Soluplus® from the NCs (69.3 ± 6.2 µgmL−1) as compared to pure drug (35.6 ± 7.2 µgmL−1). In vitro release of drug from OLA-NCs was higher (78.2%) at 12 h at pH 6.8 and relatively lower (53.1%) at pH 1.2. In vitro cellular cytotoxicity and anticancer effects were examined on MCF-7 cells. OLA-NCs were found effectively potent to MCF-7 cells compared with OLA-pure with approximately less than half IC50 value during MTT assay. Estimation of p53, Caspase-3 and Caspase-9 in MCF-7 cells indicated that OLA-NCs have significantly (p < 0.05) increased their expressions. After single oral dose in rats, 12 h plasma drug concentration-time profile indicated approximately 2.06-, 2.29-, 2−25- and 2.62-folds increased Cmax, AUC0-12 h, AUC0-∞ and AUMC0-∞, respectively, from the NCs as compared to OLA-pure. Storage stability indicated that the OLA-NCs was physically and chemically stable at 4 °C, 25 °C and 40 °C up to 6-months. Overall, OLA-NCs were deliberated; its potential feasibility to overwhelm the formulation challenges related to poorly soluble drugs and its future clinical applications.

Dissolution Behavior of Weakly Basic Pharmaceuticals from Amorphous Dispersions Stabilized by a Poly(dimethylaminoethyl Methacrylate) Copolymer

Amorphous solid dispersions (ASDs) are a well-documented formulation approach to improve the rate and extent of dissolution for hydrophobic pharmaceuticals. However, weakly basic compounds can complicate standard approaches to ASDs due to pH-dependent solubility, resulting in uncontrolled drug release in gastric conditions and unstabilized supersaturated solutions prone to precipitation at neutral pH. This work examines the release mechanisms of amorphous dispersions containing model weakly basic pharmaceuticals posaconazole and lumefantrine from a basic poly(dimethylaminoethyl methacrylate) copolymer (Eudragit EPO) and compares their dissolution behavior with ASDs stabilized by acidic and neutral polymers to understand potential benefits to release from a basic polymeric stabilizer. It was found that dissolution of Eudragit EPO ASDs resulted in supersaturation under gastric conditions, which could be sustained upon adjustment to neutral pH. However, the dissolution behavior of Eudragit EPO ASDs was sensitive to the initial pH of the gastric media. For lumefantrine, elevated initial gastric pH resulted in precipitation of amorphous nanoparticles; for posaconazole, elevated gastric pH led to crystallization of the pharmaceutical from solution. This sensitivity to gastric pH was found to originate from the impact of Eudragit EPO on gastric pH and the solubility of each pharmaceutical in the first stage of dissolution. In total, these data illustrate benefits and liabilities for the use of Eudragit EPO for ASDs containing weak pharmaceutical bases to guide the design of robust pharmaceutical formulations.

Fabrication and Characterization of Tedizolid Phosphate Nanocrystals for Topical Ocular Application: Improved Solubilization and In Vitro Drug Release

Positively charged NCs of TZP (0.1%, w/v) for ocular use were prepared by the antisolvent precipitation method. TZP is a novel 5-Hydroxymethyl-Oxazolidinone class of antibiotic and is effective against many drug-resistant bacterial infections. Even the phosphate salt of this drug is poorly soluble, therefore the NCs were prepared for its better solubility and ocular availability. P188 was found better stabilizer than PVA for TZP-NCs. Characterization of the NCs including the particle-size, PDI, and ZP by Zeta-sizer, while morphology by SEM indicated that the preparation technique was successful to get the optimal sized (151.6 nm) TZP-NCs with good crystalline morphology. Mannitol (1%, w/v) prevented the crystal growth and provided good stabilization to NC₁ during freeze-drying. FTIR spectroscopy confirmed the nano-crystallization did not alter the basic molecular structure of TZP. DSC and XRD studies indicated the reduced crystallinity of TZP-NC₁, which potentiated its solubility. An increased solubility of TZP-NC₁ (25.9 µgmL⁻¹) as compared to pure TZP (18.4 µgmL⁻¹) in STF with SLS. Addition of stearylamine (0.2%, w/v) and BKC (0.01%, w/v) have provided cationic (+29.4 mV) TZP-NCs. Redispersion of freeze-dried NCs in dextrose (5%, w/v) resulted in a clear transparent aqueous suspension of NC₁ with osmolarity (298 mOsm·L⁻¹) and viscosity (21.1 cps at 35 °C). Mannitol (cryoprotectant) during freeze-drying could also provide isotonicity to the nano-suspension at redispersion in dextrose solution. In vitro release in STF with SLS has shown relatively higher (78.8%) release of TZP from NC₁ as compared to the conventional TZP-AqS (43.4%) at 12 h. TZP-NC₁ was physically and chemically stable at three temperatures for 180 days. The above findings suggested that TZP-NC₁ would be a promising alternative for ocular delivery of TZP with relatively improved performance.

A Technical Approach of Solubility Enhancement of Poorly Soluble Drugs: Liquisolid Technique

BACKGROUND

Solubility is one of the significant pre-formulation properties which regulate the desired concentration of drug in the systemic circulation. Most of the newly discovered chemical entities show poor solubility which consequently leads to poor bioavailability. To enhance the bioavailability of such type of drugs is a big challenge for pharmaceutical scientists. Liquisolid technology is a new and advanced technology used to transform the liquid medication into dry, free-flowing and easily compressible dosage form incorporation with the carrier and coating material.

OBJECTIVES

This review represents the technical perspective of Liquisolid technologies that overcome the demerits of classic formulation strategies and amend the bioavailability of the poorly soluble drug. This technique is also approaches the stability, hygroscopicity and agglomeration issue which are mainly occurring in other techniques for solubility enhancement.

CONCLUSION

Several technologies have been utilized to minimize the solubility problem but due to the complicated and expensive machinery fails to achieve the desired bioavailability of the poorly soluble drugs. Therefore, Liquisolid technology has been introduced as an innovative and promising technique that recovers the demerits of classic formulation strategies and also improves the bioavailability of the poorly soluble drug. This article exhibits the technical approach of the liquisolid system by improving the solubility as well as bioavailability of water-insoluble drugs.

Current Evidence, Challenges, and Opportunities of Physiologically Based Pharmacokinetic Models of Atorvastatin for Decision Making

Atorvastatin (ATS) is the gold-standard treatment worldwide for the management of hypercholesterolemia and prevention of cardiovascular diseases associated with dyslipidemia. Physiologically based pharmacokinetic (PBPK) models have been positioned as a valuable tool for the characterization of complex pharmacokinetic (PK) processes and its extrapolation in special sub-groups of the population, leading to regulatory recognition. Several PBPK models of ATS have been published in the recent years, addressing different aspects of the PK properties of ATS. Therefore, the aims of this review are (i) to summarize the physicochemical and pharmacokinetic characteristics involved in the time-course of ATS, and (ii) to evaluate the major highlights and limitations of the PBPK models of ATS published so far. The PBPK models incorporate common elements related to the physicochemical aspects of ATS. However, there are important differences in relation to the analyte evaluated, the type and effect of transporters and metabolic enzymes, and the permeability value used. Additionally, this review identifies major processes (lactonization, P-gp contribution, ATS-Ca solubility, simultaneous management of multiple analytes, and experimental evidence in the target population), which would enhance the PBPK model prediction to serve as a valid tool for ATS dose optimization.

Physical formulation approaches for improving aqueous solubility and bioavailability of ellagic acid: A review

Ellagic acid (EA) is a polyphenolic active compound with antimalarial and other promising therapeutic activities. However, its solubility and its permeability are both low (BCS IV). These properties greatly compromise its oral bioavailability and clinical utilizations. To overcome these limitations of the physicochemical parameters, several formulation approaches, including particle size reduction, amorphization and lipid-based formulations, have been used. Although these strategies have not yet led to a clinical application, some of them have resulted in significant improvements in the solubility and bioavailability of EA. This critical review reports and analyses the different formulation approaches used by scientists to improve both the biopharmaceutical properties and the clinical use of EA.

Surface stabilized atorvastatin nanocrystals with improved bioavailability, safety and antihyperlipidemic potential

Atorvastatin, a favored option for hyperlipidemia exhibits the problem of poor gastric solubility and low absolute bioavailability (12%) along with higher pre-systemic clearance (>80%). Therefore, to circumvent these limitations, atorvastatin nanocrystals were prepared using poloxamer-188 as stabilizer via high pressure homogenization technique followed by lyophilization. Various variables like drug to poloxamer-188 ratio, homogenization cycle, homogenization pressure, type and concentration of cryoprotectant were optimized to achieve uniform nanosized crystals with good dispersibility. Solid state characterization by ATR-FTIR and DSC revealed no incompatible physicochemical interaction between drug and excipients in formulation while DSC and PXRD collectively corroborated the reduced crystallinity of drug in nanocrystals. Size analysis and SEM confirmed nanometric size range of nanocrystals (225.43 ± 24.36 nm). Substantial improvement in gastric solubility (~40 folds) and dissolution rate of drug in nanocrystals was observed. Pharmacokinetic study in wistar rats revealed significant improvement in oral bioavailability (~2.66 folds) with atorvastatin nanocrystals compared to pure drug. Furthermore, reduction in serum total lipid cholesterol, LDL and triglyceride content justified the effectiveness of formulation at 50% less dose of atorvastatin along with improved plasma safety profile in comparison of pure drug. In conclusion, atorvastatin nanocrystals are safe and efficacious drug delivery system confirming potent competence in treatment of hyperlipidemic conditions with ease of scalability for commercialization.

Nano-particle engineered atorvastatin delivery to support mesenchymal stem cell survival in infarcted myocardium

Atorvastatin (ATV) may support mesenchymal stem cells (MSC) survival in post-infarct myocardium (MI) as inflammatory reactions, oxidative stress and hypoxia condition get started in such tissues after damage. However, limited aqueous insolubility and rapid first-pass metabolism reduce the systemic availability of ATV. The aim of the present investigation was to develop ATV loaded nanoparticles (ATVNPs) which might ensure the maximum availability of ATV in systemic circulation for longer duration and to strengthen the support to MSC survival. ATVNPs were synthesized using double emulsion solvent evaporation method and characterized as spherical shape, positive charged, nanoparticles of uniform size distribution and higher entrapment efficiency. ATVNPs were non-cytotoxic and showed sustained release (up to 28 days). Assessment of cardiac function (in terms of echocardiographic and left heart catheterization parameters) and cytokines estimation revealed efficient improvement in post-infarct myocardium condition of rat. In conclusion, ATVNP was developed successfully that may ensure safe, cost effective, and efficacious treatment of post-infarct myo-cardium when compared with that of MSC alone and MSC supplemented with ATV solution.

Identification of Estrogen Receptor α Antagonists from Natural Products via In Vitro and In Silico Approaches

Estrogen receptor α (ERα) is a successful target for ER-positive breast cancer and also reported to be relevant in many other diseases. Selective estrogen receptor modulators (SERMs) make a good therapeutic effect in clinic. Because of the drug resistance and side effects of current SERMs, the discovery of new SERMs is given more and more attention. Virtual screening is a validated method to high effectively to identify novel bioactive small molecules. Ligand-based machine learning methods and structure-based molecular docking were first performed for identification of ERα antagonist from in-house natural product library. Naive Bayesian and recursive partitioning models with two kinds of descriptors were built and validated based on training set, test set, and external test set and then were utilized for distinction of active and inactive compounds. Totally, 162 compounds were predicted as ER antagonists and were further evaluated by molecular docking. According to docking score, we selected 8 representative compounds for both ERα competitor assay and luciferase reporter gene assay. Genistein, daidzein, phloretin, ellagic acid, ursolic acid, (-)-epigallocatechin-3-gallate, kaempferol, and naringenin exhibited different levels for antagonistic activity against ERα. These studies validated the feasibility of machine learning methods for predicting bioactivities of ligands and provided better insight into the natural products acting as estrogen receptor modulator, which are important lead compounds for future new drug design.

Reconstitutable spray dried ultra-fine dispersion as a robust platform for effective oral delivery of an antihyperlipidemic drug

The current article highlights the application of spray drying technique to produce an ultra-fine powder encapsulating the antihyperlipidemic drug, atorvastatin calcium (ATV). First, ATV was dissolved in an emulsion formulation, and different carriers (pectin, alginate, chitosan HCl and hydroxypropylmethyl cellulose) in two concentrations (1.5 and 3%) were added. Then, these carrier-containing formulations were subjected to spray drying, whereby ultra-fine ATV-loaded spray dried emulsions were produced (ATV-SDE). The optimum formulation; ATV-SDE7 containing 3% w/w pectin was selected showing an obviously enhanced dissolution profile compared to the other used polymers which could be attributed to its lower ability to swell in acidic medium, resulting in faster drug diffusion into release medium. Thus, ATV-SDE7 was subjected to further characterization including; DSC, XRPD, SEM and flowability properties. In-vivo studies were conducted using high-fat induced hyperlipidemic rats. The optimum formulation depicted normal lipid profile showing significant reduction in the measured parameters at the end of daily oral treatment, compared to ATV marketed tablets and control hyperlipidemic rats confirmed by normal liver sections upon histopathological examination. The superior lipid-lowering activity of ATV-SDE7 was not only due to the enhanced dissolution of ATV but also due to the presence of pectin which is capable of lowering both cholesterol and triglyceride serum levels. Hence, the present study suggests that the formulation strategy employing ultrafine redispersible spray dried emulsion with pectin as a carrier holds a promising approach for the development of a novel dosage form of enhanced antihyperlipidemic effect for ATV.

The Need for Restructuring the Disordered Science of Amorphous Drug Formulations

The alarming numbers of poorly soluble discovery compounds have centered the efforts towards finding strategies to improve the solubility. One of the attractive approaches to enhance solubility is via amorphization despite the stability issue associated with it. Although the number of amorphous-based research reports has increased tremendously after year 2000, little is known on the current research practice in designing amorphous formulation and how it has changed after the concept of solid dispersion was first introduced decades ago. In this review we try to answer the following questions: What model compounds and excipients have been used in amorphous-based research? How were these two components selected and prepared? What methods have been used to assess the performance of amorphous formulation? What methodology have evolved and/or been standardized since amorphous-based formulation was first introduced and to what extent have we embraced on new methods? Is the extent of research mirrored in the number of marketed amorphous drug products? We have summarized the history and evolution of amorphous formulation and discuss the current status of amorphous formulation-related research practice. We also explore the potential uses of old experimental methods and how they can be used in tandem with computational tools in designing amorphous formulation more efficiently than the traditional trial-and-error approach.