Development of lovastatin-loaded poly(lactic acid) microspheres for sustained oral delivery: in vitro and ex vivo evaluation

Sizing down and functionalizing polylactide (PLA) resin for synthesis of PLA-based polyurethanes for use in biomedical applications

Alcoholysis is a promising approach for upcycling postconsumer polylactide (PLA) products into valuable constituents. In addition, an alcohol-acidolysis of PLA by multifunctional 2,2-bis(hydroxymethyl)propionic acid (DMPA) produces lactate oligomers with hydroxyl and carboxylic acid terminals. In this work, a process for sizing down commercial PLA resin to optimum medium-sized lactate oligomers is developed at a lower cost than a bottom-up synthesis from its monomer. The microwave-assisted reaction is conveniently conducted at 220-240 °C and pressure lower than 100 psi. The PLA resin was completely converted via alcohol-acidolysis reaction, with a product purification yield as high as 93%. The resulting products are characterized by FTIR, 2D-NMR, ¹H-NMR, GPC, DSC, and XRD spectroscopy. The effects of PLA: DMPA feed ratios and the incorporation of 1,4-butanediol (BDO) on the structures, properties, and particle formability of the alcohol-acidolyzed products are examined. The products from a ratio of 12:1, which possessed optimum size and structures, are used to synthesize PLA-based polyurethane (PUD) by reacting with 1,6-diisocyanatohexane (HDI). The resulting PUD is employed in encapsulating lavender essential oil (LO). Without using any surfactant, stable LO-loaded nanoparticles are prepared due to the copolymer's self-stabilizability from its carboxylate groups. The effect of the polymer: LO feed ratio (1.25-3.75: 1) on the physicochemical properties of the resulting nanoparticles, e.g., colloidal stability (zeta potential > -60 mV), hydrodynamic size (300-500 nm), encapsulation efficiency (80-88%), and in vitro release, are investigated. The LO-loaded nanoparticles show non-toxicity to fibroblast cells, with an IC₅₀ value higher than 2000 µg/mL. The products from this process have high potential as drug encapsulation templates in biomedical applications.

Poly(Lactic Acid)-Based Microparticles for Drug Delivery Applications: An Overview of Recent Advances

The sustained release of pharmaceutical substances remains the most convenient way of drug delivery. Hence, a great variety of reports can be traced in the open literature associated with drug delivery systems (DDS). Specifically, the use of microparticle systems has received special attention during the past two decades. Polymeric microparticles (MPs) are acknowledged as very prevalent carriers toward an enhanced bio-distribution and bioavailability of both hydrophilic and lipophilic drug substances. Poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA), and their copolymers are among the most frequently used biodegradable polymers for encapsulated drugs. This review describes the current state-of-the-art research in the study of poly(lactic acid)/poly(lactic-co-glycolic acid) microparticles and PLA-copolymers with other aliphatic acids as drug delivery devices for increasing the efficiency of drug delivery, enhancing the release profile, and drug targeting of active pharmaceutical ingredients (API). Potential advances in generics and the constant discovery of therapeutic peptides will hopefully promote the success of microsphere technology.

Preparation, Characterization and in vitro/in vivo Evaluation of Lovastatin-Loaded PLGA Microspheres by Local Administration for Femoral Head Necrosis

Background

The present work is an effort to develop a novel locally injection LVTT-loaded PLGA microspheres (LVTT-PLGA-MS) on the treatment of rabbits with femoral head necrosis (FHN).

Methods

LVTT-loaded PLGA microspheres (LVTT-PLGA MS) were prepared by an emulsion-solvent evaporation method. The physicochemical properties of LVTT-PLGA-MS were investigated to ensure that they have good qualities and are suitable for local delivery. In vitro drug release behavior of MS was also studied compared with free LVTT. In vivo, we also studied the pharmacokinetics and pharmacodynamics of MS in rabbits with the optimized formulation.

Results

In this study, we used the emulsion-solvent evaporation method to prepare LVTT-PLGA MS. Scanning electron microscopy demonstrated that the LVTT-PLGA MS were regular, round in shape and relatively unified size distributions were selected. The mean PS was 12.3±2.1 µm. The drug-loading rate (27.6% ± 2.9%) was calculated for three batches of MS. The thermogram of LVTT-PLGA MS showed an endothermic peak at 98.3°C, revealing that LVTT existed in MS in an uncrystallized rather than a crystallized form. In the release study, LVTT-PLGA MS is observed linear prolonging drug release rates for more than 21 days without initial burst release. The pharmacodynamic results confirmed that the LVTT-PLGA MS had a good and lasting improvement effect against femoral head necrosis.

Conclusion

Our results demonstrated that LVTT-PLGA MS has the potential for being a local delivery system.

Nanoparticles of Lovastatin: Design, Optimization and in vivo Evaluation

Introduction

The aim of the study was to optimize the processing factors of precipitation–ultrasonication technique to prepare nano-sized particles of Lovastatin (LA) for enhancing its solubility, dissolution rate and in vivo bioavailability.

Methods

LA nanoparticles (LANs) were prepared using precipitation–ultrasonication technique under different processing factors. LANs were characterized in terms of particle size, zeta potential and in vitro release. Stability studies at 4°C, 25°C and 40°C were conducted for optimum formulation. In addition, the in vivo bioavailability of the optimum formula was studied in comparison to a marketed product in white master rats.

Results

The optimized LAN formula (LAN15) had particle size (190±15), polydispersity index (0.626±0.11) and a zeta potential (−25±1.9 mV). The dissolution study of the nanosuspensions showed significant enhancement compared with pure drug. After 50 min, only 20.12±1.85% of LA was dissolved while 99.1±1.09% of LA was released from LAN15. Stability studies verified that nanosuspensions at 4°C and 25°C showed higher stability with no particle growth compared to the samples studied at 40°C. In vivo studies conducted in rats verified that there was 1.45-fold enhancement of C_max of LAN15 as compared to marketed tablets.

Conclusion

Nanoparticle prepared by ultrasonication-assisted precipitation method is a promising formula for enhancing the solubility and hence the bioavailability of Lovastatin.

Micro and nanoscale technologies in oral drug delivery

Oral administration is a pillar of the pharmaceutical industry and yet it remains challenging to administer hydrophilic therapeutics by the oral route. Smart and controlled oral drug delivery could bypass the physiological barriers that limit the oral delivery of these therapeutics. Micro- and nanoscale technologies, with an unprecedented ability to create, control, and measure micro- or nanoenvironments, have found tremendous applications in biology and medicine. In particular, significant advances have been made in using these technologies for oral drug delivery. In this review, we briefly describe biological barriers to oral drug delivery and micro and nanoscale fabrication technologies. Micro and nanoscale drug carriers fabricated using these technologies, including bioadhesives, microparticles, micropatches, and nanoparticles, are described. Other applications of micro and nanoscale technologies are discussed, including fabrication of devices and tissue engineering models to precisely control or assess oral drug delivery in vivo and in vitro, respectively. Strategies to advance translation of micro and nanotechnologies into clinical trials for oral drug delivery are mentioned. Finally, challenges and future prospects on further integration of micro and nanoscale technologies with oral drug delivery systems are highlighted.

Development and in vitro evaluation of (β-cyclodextrin-g-methacrylic acid)/Na+-montmorillonite nanocomposite hydrogels for controlled delivery of lovastatin

Background: Hyperlipidemia is the elevation of low density lipoprotein levels resulting in fat deposites in arteries and their hardening and blockage.  It is the leading cause of several life threatening pathological conditions like hypertension, cardiovascular diseases, diabetes etc. Purpose: The objective of this study was to prepare and optimize nontoxic, biocompatible β-CD-g-MAA/Na+-MMT nanocomposite hydrogels with varying content of polymer, monomer and montmorillonite. Moreover, lipid lowering potentials were determined and compared with other approaches. Methods: β-CD-g-MAA/Na+-MMT nanocomposite hydrogels (BM-1 to BM9) were prepared through free radical polymerization by using  β-CD  as polymer, MAA as monomer, MBA as crosslinker and montmorillonite as clay. Developed networks were evaluated for FTIR, DSC, TGA, PXRD, SEM, sol-gel fraction (%), swelling studies, antihyperlipidemic studies and toxicity studies. Results: Optimum swelling (94.24%) and release (93.16%) were obtained at higher pH values. Based on R2 and "n" value LVT release followed zero order kinetics with Super Case II transport release mechanism, respectively. Tensile strength and elongation at break were found to be 0.0283MPa and 94.68%, respectively. Gel fraction was between 80.55 - 98.16%. Antihyperlipidemic studies revealed that LDL levels were markedly reduced from 522.24 ± 21.88mg/dl to 147.63 ± 31.5mg/dl. Toxicity studies assured the safety of developed network. Conclusion: A novel pH responsive crosslinked network containing β-CD - g - poly (methacrylic acid) polymer and MMT was developed and optimized with excellent mechanical, swelling and release properties and lipid lowering potentials.

Drug Solubility Enhancement through the Preparation of Multicomponent Organic Materials: Eutectics of Lovastatin with Carboxylic Acids

Lovastatin (LOV) is a drug used to treat hypercholesterolemia. Recent studies have identified its antioxidant effects and potential use in the treatment of some types of cancer. However, the low bioavailability related to its poor water solubility limits its use in solid oral dosage forms. Therefore, to improve the solubility of LOV three eutectic systems of LOV with the carboxylic acids benzoic (BEN), salicylic (SAL) and cinnamic (CIN) were obtained. Both binary phase and Tammann diagrams were constructed using differential scanning calorimetry (DSC) data of mixtures prepared from 0.1 to 1.0 molar ratios. Binary mixtures and eutectics were prepared by liquid-assisted grinding. The eutectics were further characterized by DSC and powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The LOV-BEN, LOV-SAL and LOV-CIN system formed a eutectic at an LOV mole fraction of 0.19, 0.60 and 0.14, respectively. The systems exhibited improvements in LOV solubility, becoming more soluble by five-fold in the LOV-SAL system and approximately four-fold in the other two systems. Considering that the solubility enhancements and the carboxylic acids used are generally recognized as safe by the U.S. Food and Drug Administration (FDA), the LOV eutectic systems are promising materials to be used in a solubility enhancement strategy for pharmaceutical product formulation.

Controlled drug delivery for glaucoma therapy using montmorillonite/Eudragit microspheres as an ion-exchange carrier

Background

Glaucoma is a serious eye disease that can lead to loss of vision. Unfortunately, effective treatments are limited by poor bioavailability of antiglaucoma medicine due to short residence time on the preocular surface.

Materials and methods

To solve this, we successfully prepared novel controlled-release ion-exchange microparticles to deliver betaxolol hydrochloride (BH). Montmorillonite/BH complex (Mt-BH) was prepared by acidification-intercalation, and this complex was encapsulated in microspheres (Mt-BH encapsulated microspheres [BMEMs]) by oil-in-oil emulsion-solvent evaporation method. The BH loaded into ion-exchange Mt was 47.45%±0.54%. After the encapsulation of Mt-BH into Eudragit microspheres, the encapsulation efficiency of BH into Eudragit microspheres was 94.35%±1.01% and BH loaded into Eudragit microspheres was 14.31%±0.47%.

Results

Both Fourier transform infrared spectra and X-ray diffraction patterns indicated that BH was successfully intercalated into acid-Mt to form Mt-BH and then Mt-BH was encapsulated into Eudragit microspheres to obtain BMEMs. Interestingly, in vitro release duration of the prepared BMEMs was extended to 12 hours, which is longer than both of the BH solution (2.5 hours) and the conventional BH microspheres (5 hours). Moreover, BMEM exhibited lower toxicity than that of BH solution as shown by the results of cytotoxicity tests, chorioallantoic membrane-trypan blue staining, and Draize rabbit eye test. In addition, both in vivo and in vitro preocular retention capacity study of BMEMs showed a prolonged retention time. The pharmacodynamics showed that BMEMs could extend the drug duration of action.

Conclusion

The developed BMEMs have the potential to be further applied as ocular drug delivery systems for the treatment of glaucoma.

Simultaneous saccharification and fermentation (SSF) of jackfruit seed powder (JFSP) to l-lactic acid and to polylactide polymer

A newly isolated amylolytic lactic acid bacterium, Streptococcus equinus, was used for the production of l-lactic acid from jackfruit seed powder (JFSP) by simultaneous saccharification and fermentation (SSF). After optimization of shake flask fermentation by a response surface box-behnken design, the maximum lactate titer was 109g/L from 200g/L jackfruit seed powder. Amberlite IRA67, a weak base resin, was used to recover pure lactic acid from fermented broth and subsequently used for the synthesis of polylactic acid by direct condensation polymerization method with a yield of 62%.

Controlled biodegradation of polymers using nanoparticles and its application

Controlled biodegradation mechanism has been revealed using different nanoparticles which eventually regulate pH of media.

Improvement of oral bioavailability of lovastatin by using nanostructured lipid carriers

Nanostructured lipid carriers (NLCs) have been one of the systems of choice for improving the oral bioavailability of drugs with poor water solubility. In the present study, lovastatin (LVT)-loaded NLCs (LVT-NLCs) were successfully prepared by hot high-pressure homogenization method with high entrapment efficiency, drug loading, and satisfactory particle size distribution. The particles had almost spherical and uniform shapes and were well dispersed with a particle size of <50 nm (23.5 ± 1.6 nm) and a low polydispersity index (0.17 ± 0.05 mV). The result of stability showed that the LVT-NLCs dispersion maintained excellent stability without exhibiting any aggregation, precipitation, or phase separation at 4 °C for 6 months of storage. The LVT release data from all developed solid lipid nanoparticles (SLNs) and NLCs were best fitted to a Ritger-Peppas kinetic model (0.9832 and 0.9783 for NLCs and SLNs, respectively). This indicated that the release of LVT from the SLNs and NLCs was due to a combination of drug diffusion and erosion from the lipid matrix. The pharmacokinetic and pharmacodynamic results show that LVT-NLCs were better compared to free drug, which could be attributed to an increase in bioavailability.