The effect of the saturation degree of phospholipid on the formation of a novel self-assembled nano-micellar complex carrier with enhanced intestinal permeability.

The aim of this research was to formulate a novel nano-micellar complex carrier with intrinsically enhanced intestinal permeability for rosuvastatin calcium (RSV); as a model of BCS class III active pharmaceutical ingredients (APIs). The model drug is used primarily for treating hypercholesterolemia. Three phospholipid types with different degrees of saturation were chosen for the study. The saturation degree of the phospholipids was calculated accurately by proton NMR. A D-optimal statistical design was utilized to correlate the saturation degree of the phospholipids with the physico-chemical characteristics of the prepared nano-micellar carrier. The nature of the interaction between the phospholipids and the model drug was studied by proton NMR, photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). Molecular docking and molecular dynamics simulations were performed to understand the formation mechanism of the complex micelles on a molecular level. The results demonstrated that the interaction of the hydrophilic drug molecule with the polar head of a saturated phospholipid induces an intramolecular self-coiling of phospholipid saturated acyl chain leading to a structural transformation from a two-tailed cylindrical configuration into a one-tailed, surfactant-like configuration owing to the flexibility of the saturated chains. This transformation leads to the construction of a novel nano-micellar structure in which the drug has lower water solubility but higher lipophilicity than in traditional micelles. Permeability studies conducted on Caco-2 cells demonstrated that the novel nano-micellar carrier had superior permeability to that of the un-complexed hydrophilic drug. The optimized nano-micellar formulation showed significantly (P < 0.5) superior bioavailability in rats to that of the aqueous drug solution in terms of both the rate and extent of drug absorption. Overall, the results confirmed that the formation of the phospholipid nano-micellar complex increased the permeability of the hydrophilic BCS class III drug and converted it to a class BCS I drug by a simple and effective formulation technique.

Preparation of novel phospholipid-based sonocomplexes for improved intestinal permeability of rosuvastatin: In vitro characterization, dynamic simulation, Caco-2 cell line permeation and in vivo assessment studies.

The study aimed to fabricate innovative drug-phospholipid complexes termed "sonocomplexes" adopting ultrasound irradiation to increase the liposolubility and to enhance the intestinal absorption of rosuvastatin as a model drug for BCS class III active pharmaceutical ingredients (APIs). A 22 full factorial design was fashioned to investigate the influence of phosphatidylcholine content in the phospholipid (∼30 and 60%) and molar ratio of phospholipid to rosuvastatin (1:1 and 2:1) on physicochemical properties of sonocomplexes. In comparison to pure drug, sonocomplexes showed a minimum of about 2 folds and a maximum of about 15 folds increase in lipophilicity (expressed in terms of partition coefficient, P). Results of molecular docking, dynamic simulations, Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) confirmed the strong interactions between rosuvastatin and the phospholipid via hydrogen bonding interaction, van der Waals forces and hydrophobic interaction. The complexation efficiency reached around 99% and transmission electron microscopy (TEM) of the aqueous dispersion of the optimal sonocomplex showed spherical nanosized vesicles. The optimal sonocomplex showed significantly superior Caco-2 cells permeability and markedly better oral bioavailability compared to the pure drug. In summary, sonocomplexes can be considered as effective approach for enhancing the liposolubility and consequently the intestinal permeability of BCS class III drugs.

Duodenum-triggered delivery of pravastatin sodium: II. Design, appraisal and pharmacokinetic assessments of enteric surface-decorated nanocubosomal dispersions.

CONTEXT: Pravastatin sodium (PVS) is a freely water-soluble HMG-CoA inhibitor that suffers from instability at gastric pH, extensive first pass metabolism, short elimination half-life (1-3 h) and low oral bioavailability (18%). OBJECTIVE: To overpower these drawbacks and to maximize drug absorption at its main site of absorption at the duodenum, enteric surface-coated PVS-loaded nanocubosomal dispersions were presented. MATERIALS AND METHODS: Glyceryl monooleate (GMO)-based dispersions were developed by the fragmentation or the liquid precursor methods using Pluronic® F127 or Cremophor® EL as surfactants. As a challenging enteric-coating approach, the promising dispersions were surface-coated via lyophilization with Eudragit® L100-55; a duodenum-targeting polymer. The drug content, particle size, zeta potential, morphology and release studies of PVS-loaded dispersions were evaluated before and after surface-coating. Compared to an aqueous PVS solution, the pharmacokinetics of the best achieved system (E-F8) was evaluated (UPLC-MS/MS) in rats. RESULTS: The enteric surface-coated nanocubosomal dispersions were more or less spherical in shape and showed high drug-loading, negative zeta potential values and fine-tuned biphasic drug-release patterns characterized by retarded (2 h) and sustained (10 h) phases in pH 1.2 and pH 6.8, respectively. E-F8 system showed significantly (p< 0.05) higher oral bioavailability, delayed Tmax and prolonged MRT0-∞ following oral administration in rats. CONCLUSIONS: The duodenum-triggering potential and the controlled-release characteristics of the best achieved system for smart PVS delivery were revealed.

Duodenum-triggered delivery of pravastatin sodium via enteric surface-coated nanovesicular spanlastic dispersions: development, characterization and pharmacokinetic assessments.

Pravastatin sodium (PVS) is a hydrophilic HMG-CoA reductase inhibitor that is mainly absorbed from duodenum. PVS has a short elimination half-life (1-3 h), suffers from instability at gastric pH, extensive hepatic first-pass metabolism and low absolute bioavailability (18%). The current work aimed to develop enteric surface-coated spanlastic dispersions as controlled-release duodenum-triggered systems able to surmount PVS drawbacks. PVS-loaded spanlastic dispersions were prepared by ethanol-injection method using span(®) 60. Tween(®) 60 and Tween(®) 80 were explored as edge activators. As a novel approach, the fine spanlastic dispersions were surface-coated with an enteric-polymer (Eudragit(®) L100-55) via freeze-drying. The systems were evaluated, before and after enteric-coating, for particle size, zeta potential, PVS entrapment efficiency (EE%), morphology and PVS release studies. PVS pharmacokinetics from the best achieved system and an aqueous solution were estimated in rats by UPLC-MS/MS. The best achieved enteric surface-coated spanlastic dispersion (E-S6) displayed spherical nanosized vesicles (647.60 nm) possessing negative zeta potential (-6.93 mV), promising EE% (63.22%) and a biphasic drug-release pattern characterized by a retarded-release phase (0.1 N HCl, 2 h) and a controlled-release phase (pH 6.8, 10 h). The higher Cmax, delayed Tmax, prolonged MRT(0-∞), longer elimination t50% and enhanced oral bioavailability unravel E-S6 potential for oral PVS delivery.

Positively charged polymeric nanoparticle reservoirs of terbinafine hydrochloride: preclinical implications for controlled drug delivery in the aqueous humor of rabbits.

Frequent instillation of terbinafine hydrochloride (T HCl) eye drops (0.25%, w/v) is necessary to maintain effective aqueous humor concentrations for treatment of fungal keratitis. The current approach aimed at developing potential positively charged controlled-release polymeric nanoparticles (NPs) of T HCl. The estimation of the drug pharmacokinetics in the aqueous humor following ocular instillation of the best-achieved NPs in rabbits was another goal. Eighteen drug-loaded (0.50%, w/v) formulae were fabricated by the nanopreciptation method using Eudragit® RS100 and chitosan (0.25%, 0.5%, and 1%, w/v). Soybean lecithin (1%, w/v) and Pluronic® F68 (0.5%, 1%, and 1.5%, w/v) were incorporated in the alcoholic and aqueous phases, respectively. The NPs were evaluated for particle size, zeta potential, entrapment efficiency percentage (EE%), morphological examination, drug release in simulated tear fluid (pH 7.4), Fourier-transform IR (FT-IR), X-ray diffraction (XRD), physical stability (2 months, 4°C and 25°C), and drug pharmacokinetics in the rabbit aqueous humor relative to an oily drug solution. Spherical, discrete NPs were successfully developed with mean particle size and zeta potential ranging from 73.29 to 320.15 nm and +20.51 to +40.32 mV, respectively. Higher EE% were achieved with Eudragit® RS100-based NPs. The duration of drug release was extended to more than 8 h. FT-IR and XRD revealed compatibility between inactive formulation ingredients and T HCl and permanence of the latter's crystallinity, respectively. The NPs were physically stable, for at least 2 months, when refrigerated. F5-NP suspension significantly (P<0.05) increased drug mean residence time and improved its ocular bioavailability; 1.657-fold.

Promising ion-sensitive in situ ocular nanoemulsion gels of terbinafine hydrochloride: design, in vitro characterization and in vivo estimation of the ocular irritation and drug pharmacokinetics in the aqueous humor of rabbits.

Terbinafine hydrochloride (T-HCl) is recommended for the management of fungal keratitis. To maintain effective aqueous humor concentrations, frequent instillation of T-HCl drops is necessary. This work aimed to develop alternative controlled-release in situ ocular drug-loaded nanoemulsion (NE) gels. Twelve pseudoternary-phase diagrams were constructed using oils (isopropyl myristate/Miglyol 812), surfactants (Tween 80/Cremophor EL), a co-surfactant (polyethylene glycol 400) and water. Eight drug-loaded (0.5%, w/v) NEs were evaluated for thermodynamic stability, morphology, droplet size and drug release in simulated tear fluid (pH 7.4). Following dispersion in gellan gum solution (0.2%, w/w), the in situ NE gels were characterized for transparency, rheological behavior, mucoadhesive force, drug release and histopathological assessment of ocular irritation. Drug pharmacokinetics of sterilized F31 [Miglyol 812, Cremophor EL: polyethylene glycol 400 (1:2) and water (5, 55 and 40%, w/w, respectively)] in situ NE gel and oily drug solution were evaluated in rabbit aqueous humor. The NEs were thermodynamically stable and have spherical droplets (<30 nm). The gels were transparent, pseudoplastic, mucoadhesive and showed more retarded zero-order drug release rates. F31 in situ NE gel showed the least ocular irritation potential and significantly (P<0.01) higher C(max), delayed T(max), prolonged mean residence time and increased bioavailability.