Comparative studies of the in vitro dissolution and in vivo pharmacokinetics for different formulation strategies (solid dispersion, micronization, and nanocrystals) for poorly water-soluble drugs: A case study for lacidipine

Ternary solid dispersions of lacidipine: Enhancing dissolution and supersaturation maintenance through strategic formulation optimization

The study aimed to address the challenges related to insufficient dissolution and maintenance of supersaturation in binary solid dispersions. Lacidipine, categorized as a BCS class II drug, was employed as the model drug. A systematic screening of excipients was conducted to determine the most effective carriers for the formulations of the ternary solid dispersions, utilizing the solvent transfer method and equilibrium solubility measurements. Both binary and ternary solid dispersions were prepared via spray drying, and comprehensive physicochemical characterization confirmed the successful preparation of amorphous solid dispersions. In vitro dissolution tests, the ternary solid dispersion exhibited marked superiority over the binary solid dispersion in dissolution and maintenance of supersaturation. Furthermore, an exploration into the factors influencing the stability of ternary solid dispersions revealed their robust resistance under light-protected, room-temperature, and desiccated conditions. The formation of intermolecular hydrogen bonding within the molecules of the ternary solid dispersions significantly enhanced drug solubility and system stability. Strategic formulation optimization, coupled with judicious selection of suitable carrier types and ratios, may serve as a promising approach for designing supersaturated drug delivery systems.

Research progress on the preparation and application of flavonoid nanocrystals

Flavonoids have been reported to possess significant pharmacological activities,such as antioxidant, anti-inflammatory and anticancer effects. However, the low solubility and low bioavailability limits their clinical application. Nanocrystal technology can solve the delivery problems of flavonoids by reducing particle size, increasing the solubility of insoluble drugs and improving their bioavailability. This article summaries nanosuspension preparation methods and the stabilizers for flavonoid nanocrystals, and reviews the drug delivery routes including oral, Injection and transdermal of flavonoid nanocrystals, to provide information for further research on nanocrystal delivery system of flavonoids.

Improved transdermal permeability of tanshinone IIA from cataplasms by loading onto nanocrystals and porous silica

Novel transdermal cataplasms have been designed to improve permeability of poorly soluble drugs by different pretreatments. Nanocrystal and porous silica solid dispersions were loaded with Tanshinone IIA and incorporated into a cross-linked hydrogel matrix of cataplasm. It was shown that the small particle size and improved dissolution would increase dermal bioavailability. The adhesion, rheological properties, drug release, skin permeation, skin deposition and in vivo skin absorption of the different formulations were investigated. In an in vitro experiment using mouse skin, cumulative amount of drug permeated within 24 h was 7.32 ± 0.98 μg/cm² from conventional cataplasm, 13.14 ± 0.70 μg/cm² from nanocrystal-loaded cataplasm and 11.40 ± 0.13 μg/cm² from porous silica solid dispersion-loaded cataplasm. In vitro dissolution profiles showed that drug release was 76.5% and 74.9% from two optimized cataplasms within 24 h, while conventional cataplasm was 55.0%. The cross-linking characteristics of the cataplasms were preserved after incorporation of different drug forms, while the elastic and viscous behaviors of the hydrogel layers increased. In vivo evaluation by CLSM showed the more favorable skin permeation for two optimized cataplasms. These findings suggest that applications of nanocrystal and porous silica systems on cataplasms enable effective transdermal delivery of poorly soluble drugs. The resulting drug delivery and rheological properties are desirable for transdermal application.AbbreviationAll the abbreviations that appear in this article are shown in Table 1.

Lacidipine: review of analytical methods developed for pharmaceutical dosage forms and biological fluids

Lacidipine (LAC) is a calcium antagonist used in the treatment of hypertension. It is a lipophilic drug containing dihydropyridine ring that is responsible for the activity. This review article gives an overview of various analytical techniques proposed for the determination of LAC in pharmaceutical dosage forms, in pure form, in biological fluids and to determine characteristics of LAC in modified release dosage forms. Ultra violet/visible spectrophotometric, spectroflourimetric, high performance liquid chromatography, high performance thin layer chromatography, electro-analytical, bioanalytical and miscellaneous methods such as microbiological assay, X-ray diffraction, differential scanning calorimetry, were discussed. Various parameters such as system suitability, selectivity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness have been discussed for the employed methods.

Comparison of 1-Palmitoyl-2-Linoleoyl-3-Acetyl-Rac-Glycerol-Loaded Self-Emulsifying Granule and Solid Self-Nanoemulsifying Drug Delivery System: Powder Property, Dissolution and Oral Bioavailability

The main objective of this study was to compare the powder property, dissolution and bioavailability of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG)-loaded self-emulsifying granule system (SEGS) and solid self-nanoemulsifying drug delivery system (SNEDDS). Various SEGS formulations were prepared, and the effect of surfactant and binder on the drug solubility in them, leading to selecting sodium lauryl sulphate (SLS) and hydroxyl propyl methyl cellulose (HPMC). The SEGS and SNEDDS were prepared with PLAG/SLS/HPMC/calcium silicate/microcrystalline cellulose at the weight ratio of 1:0.25:0.1:0.5:3 employing the fluid bed granulation and spray-drying technique, respectively. Their powder properties were compared in terms of flow ability, emulsion droplet size, scanning electron microscopy, and powder X-ray diffraction. Furthermore, the solubility, dissolution, and oral bioavailability in rats of the SEGS were assessed in comparison with the SNEDDS. The SEGS and SNEDDS enhanced the solubility of the drug approximately 36- and 32-fold as compared with the drug alone; but they had no differences. The crystalline drug may exist in both the calcium silicate and microcrystalline cellulose (MCC) in the SEGS, but only in the calcium silicate in the SNEDDS. The SEGS had considerably improved the flow ability (Hausner ratio, 1.23 vs. 1.07; Carr index, 19.8 vs. 43.5%) and drug dissolution as compared with the SNEDDS. The SEGS and SNEDDS with double peak profiles, unlike the single peak of drug alone, showed a significantly higher plasma concentration and area under the curve (AUC), as compared with drug alone. Although they were not significantly different, the SEGS gave higher AUC than did the SNEDDS, suggesting its enhanced oral bioavailability of PLAG. Thus, the SEGS could be used as a powerful oral dosage form to improve the flow ability and oral bioavailability of PLAG, an oily drug.

Synergetic effect of nucleation and crystal growth inhibitor on in vitro-in vivo performance of supersaturable lacidipine solid dispersion

Limited supersaturation maintaining duration is the main challenge for amorphous solid dispersion design. Nucleation or crystal growth inhibitors may function in different ways but the combination use of nucleation and crystal growth inhibitors in supersaturated system is rarely explored. Thus, using Lacidipine (LCDP) as a Biopharmaceutical Classification System (BCS) II model drug, the aim of this study was to explore whether the combination use of nucleation and crystal growth inhibitors could provide a synergistic effect on the in vitro-in vivo performance of poorly water-soluble drugs. First of all, based on compatibility screening using solubility parameter (Δδ) and crystallization inhibition efficiency as criteria, soluplus (SOL) and gum arabic (GA) were selected as the most effective nucleation and crystal growth inhibitor respectively. Thereafter, the supersaturated drug solutions were spray dried and characterized. The in vitro release, physical stability as well as pharmacokinetic behavior were investigated. It was found that the combination use of SOL and GA did not present remarkable advantage in prolonging the supersaturation time in solution state. However, their synergistic effect in equilibrium solubility and dissolution enhancement was noticed at SOL/GA ratio 3:1, with 5-7 times higher dissolution rate observed for LCDP/SOL/GA based formulation compared with that of LCDP/SOL, which was maintained even after three months accelerated stability test under non-sink condition. Moreover, compared to the LCDP/SOL formulation, approximately 2.8 and 2.5-fold increase in the maximum plasma concentration (C_max) and the area under the plasma-time curve (AUC_0-∞) was achieved with LCDP/SOL/GA based formulation. Possible mechanism of the synergistic effect was elucidated, indicating GA may penetrate into SOL particles providing both electrostatic and steric stabilization. In conclusion, the combination use of screened nucleation and crystal growth inhibitors might be an efficient approach to design supersaturated drug delivery system.

Engineering of solidified glyburide nanocrystals for tablet formulation via loading of carriers: downstream processing, characterization, and bioavailability

INTRODUCTION

Presenting poorly water-soluble drugs as nanoparticles has shown to be an effective technique in enhancing drug dissolution rate, intrinsic solubility, and thus oral bioavailability. Nevertheless, working with nanoparticles introduces many challenges, one of which is their physical instability. Formulating nanoparticles into a solid dosage form may overcome such challenges and thus unlock the potential benefits of nanosizing.

METHODS

The current work investigates the possibility of developing a novel solid dosage form, with enhanced dissolution rate, whereby nanocrystals (~400 nm) of the class II Biopharmaceutical Classification System drug, glyburide (GBD) were fabricated through combined precipitation and homogenization procedures. Using a novel, but scalable, spraying technique, GBD nanocrystals were loaded onto commonly used tablet fillers, water-soluble lactose monohydrate (LAC), and water insoluble microcrystalline cellulose (MCC). Conventional tableting processes were then used to convert the powders generated into a tablet dosage form.

RESULTS

Studies of redispersibility showed considerable preservation of size characteristics of GBD nanocrystals during downstream processing with redispersibility indices of 105 and 118 for GBD-LAC and GBD-MCC, respectively. Characterization by differential scanning calorimetry, powder X-ray diffraction, and scanning electron microscopy showed that the powders generated powders contained nanosized crystals of GBD which adhered to carrier surfaces. Powder flowability was characterized using Hausner ratio (HR) and Carr's index (CI). GBD-LAC-loaded particles exhibited poor flowability with CI and HR of 37.5% and 1.60, respectively, whilst GBD-MCC particles showed a slightly improved flowability with CI and HR of 26.47% and 1.36, respectively. The novel tablet dosage form met US Pharmacopeia specifications, including drug content, hardness, and friability.

CONCLUSION

Higher dissolution rates were observed from the nanocrystal-based tablets compared to the microsized and commercial drug formulations. Moreover, the novel nanocrystal tablet dosage forms showed enhanced in vivo performance with area under the plasma concentration- time curve in the first 24 hours values 1.97 and 2.24 times greater than that of marketed tablets.

Lacidipine Amorphous Solid Dispersion Based on Hot Melt Extrusion: Good Miscibility, Enhanced Dissolution, and Favorable Stability

The present study aimed to increase the in vitro dissolution rate of lacidipine, a poorly water-soluble drug, by formulating amorphous solid dispersions (ASDs) using hot-melt extrusion (HME). Differential scanning calorimetry, powder X-ray diffraction, polarized light microscopy, and Fourier transform infrared were used to characterize the optimal formulations and evaluate the physical stability for the stress test. Film-casting method and hot-stage microscopy were applied to study the miscibility of lacidipine and the drug carriers. In vitro dissolution tests were conducted as the final evaluation index. The optimal formulations were successfully obtained with Soluplus and PVP VA64 at a drug/carrier ratio of 1:10 (w/w), Fourier transform infrared studies revealed the hydrogen bonding between drug and polymers, and in vitro dissolution rates of the optimal formulations were extremely enhanced compared to bulk lacidipine and physical mixtures, similar with that of the commercial tablet. The ASD formulated with Soluplus showed better physical stability than that with PVP VA64. A strong hydrogen bonding and good drug-polymer miscibility were essential to hinder the recrystallization of lacidipine ASDs. In conclusion, the lacidipine ASD formulated with Soluplus showed a significant increase in in vitro dissolution rate and favorable physical stability in the stress test.

Understanding the generation and maintenance of supersaturation during the dissolution of amorphous solid dispersions using modulated DSC and 1H NMR

In this study, the dissolution behaviour of dipyridamole (DPM) and cinnarizine (CNZ) spray-dried amorphous solid dispersions (ASDs) using polyvinyl pyrrolidone (PVP) and polyacrylic acid (PAA) as a carrier matrix were evaluated and compared. The drug concentrations achieved from the dissolution of PVP and PAA solid dispersions were significantly greater than the equilibrium solubility of crystalline DPM and CNZ in phosphate buffer pH 6.8 (PBS 6.8). The maximum drug concentration achieved by dissolution of PVP and PAA solid dispersions did not exceed the theoretically calculated apparent solubility of amorphous DPM and CNZ. However, the degree of supersaturation of DPM and CNZ increased considerably as the polymer weight fraction within the solid dispersion increased. In addition, the supersaturation profile of DPM and CNZ were studied in the presence and absence of the polymers. PAA was found to maintain a higher level of supersaturation compared to PVP. The enhanced drug solution concentration following dissolution of ASDs can be attributed to the reduced crystal growth rates of DPM and CNZ at an equivalent supersaturation. We have also shown that, for drugs having high crystallization tendency and weak drug-polymer interaction, the feasible way to increase dissolution might be increase the polymer weight fraction in the ASD. Solution ¹H NMR spectra were used to understand dissolution mechanism and to identify drug-polymer interaction. The change in electron densities of proton attached to different groups in DPM and CNZ suggested drug-polymer interaction in solution. The relative intensities of peak shift and nature of interaction between drug and polymer in different systems are different. These different effects suggest that DPM and CNZ interacts in a different way with PVP and PAA in solution which goes some way towards explaining the different polymeric effect, particularly in terms of inhibition of drug recrystallization and dissolution of DPM and CNZ ASDs. These results established that the different drug/polymer interactions in the solid state and in solution give rise to the variation in dissolution profile observed for different systems.

Stabilizing Agents for Drug Nanocrystals: Effect on Bioavailability

Drug nanocrystals are a versatile option for drug delivery purposes, and while the number of poorly soluble drug materials is all the time increasing, more research in this area is performed. Drug nanocrystals have a simple structure-a solid drug core is surrounded by a layer of stabilizing agent. However, despite the considerably simple structure, the selection of an appropriate stabilizer for a certain drug can be challenging. Mostly, the stabilizer selection is based purely on the requirement of physical stability, e.g., maintaining the nanosized particle size as long as possible after the formation of drug nanocrystals. However, it is also worth taking into account that stabilizer can affect the bioavailability in the final formulation via interactions with cells and cell layers. In addition, formation of nanocrystals is only one process step, and for the final formulation, more excipients are often added to the composition. The role of the stabilizers in the final formulation can be more than only stabilizing the nanocrystal particle size. A good example is the stabilizer's role as cryoprotectant during freeze drying. In this review, the stabilizing effect, role of stabilizers in final nanocrystalline formulations, challenges in reaching in vitro-in vivo correlation with nanocrystalline products, and stabilizers' effect on higher bioavailability are discussed.