Khaled M. Hosny

Sildenafil citrate as oral solid lipid nanoparticles: a novel formula with higher bioavailability and sustained action for treatment of erectile dysfunction

Objective: The aim of this study was to prepare sildenafil citrate as solid lipid nanoparticles (SLNs), in order to find an innovative way for alleviating the disadvantages associated with commercially available sildenafil citrate tablets. These limitations include poor solubility and extensive first-pass metabolism, resulting in low (40%) bioavailability and short elimination half-life (4 h). Methods: SLNs were prepared by hot homogenization followed by ultrasonication. Solubility of sildenafil citrate in different solid lipids was measured, effect of process variables as surfactant type and concentration, homogenization time, ultrasonication time and charge-inducing agent on the particle size, zeta potential and encapsulation efficiency were also determined. Furthermore, in vitro drug release, stability and in vivo pharmacokinetics were studied in rabbits Results: The best SLN formula consisted of 2% precirol ATO5, 0.5% phosphatidylcholine, 2.5% gelucire 44/14, 0.125% stearylamine, had an average particle size of 28.5 nm with 95.34% entrapment efficiency and demonstrated a controlled drug release over 24 h. An in vivo pharmacokinetic study revealed enhanced bioavailability by > 1.87 fold, and the mean residence time was longer than that for the commercially available tablet. Conclusion: SLN could be a promising carrier for sustained/prolonged sildenafil citrate release with enhanced oral bioavailability.

Optimization of gatifloxacin liposomal hydrogel for enhanced transcorneal permeation

The aim of this study was to prepare and characterize a topically effective prolonged-release ophthalmic gatifloxacin liposomal hydrogel formulation. Reverse-phase evaporation was used for the preparation of liposomes consisting of phosphatidylcholine (PC) and cholesterol (CH). The effect of PC:CH molar ratio on the percentage of drug encapsulated was investigated. The effect of additives, such as stearylamine (SA) or dicetyl phosphate (DP), as positive and negative charge inducers, respectively, was studied. Morphology, mean size, encapsulation efficiency, and in vitro release of gatifloxacin from liposomes were evaluated. For hydrogel preparation, carbopol 940 was applied. In vitro transcorneal permeation through excised albino rabbit cornea was also determined. Optimal encapsulation efficiency was found at the 5:3 PC:CH molar ratio; by increasing CH content above this limit, the encapsulation efficiency decreased. Positively charged liposomes showed superior entrapment efficiency over other liposomes. Hydrogel-containing liposomes with lipid content PC, CH, and SA in a molar ratio of 5:3:1, respectively, showed best release and transcorneal permeation. These results suggest that the encapsulation of gatifloxacin into liposomes prolonged the in vitro release, depending on composition of the vesicles. In addition, the polymer hydrogel used in the preparation ensured steady, prolonged transcorneal permeation. In conclusion, gatifloxacin liposomal hydrogel is a suitable delivery system for the improvement of the ocular bioavailability of gatifloxacin.

The formulation of a nasal nanoemulsion zaleplon in situ gel for the treatment of insomnia

Background: Zaleplon is a drug used for the treatment of insomnia and is available in tablet form; however, it has two major problems. First, the drug undergoes extensive first pass metabolism, resulting in only 30% bioavailability, and second, the drug has a poor aqueous solubility, which delays the onset of action. Objective: The objective of this study is to utilise nanotechnology to formulate zaleplon into a nasal in situ nanoemulsion gel (NEG) to provide a solution for the previously mentioned problems. Methods: The solubility of zaleplon in various oils, surfactants and co-surfactants was estimated. Pseudo-ternary phase diagrams were developed and various nanoemulsion (NE) formulations were prepared; these formulations were subjected to visual characterisation, thermodynamic stability study and droplet size and conductivity measurements. Carbopol 934 was used as an in situ gelling agent. The gel strength, pH, gelation time, in vitro release and ex vivo nasal permeation were determined. The pharmacokinetic study of the NEG was carried out in rabbits. Results: Stable NEs were successfully developed with a droplet size range of 35 to 73 nm. A NEG composed of 15% Miglyol, 30% Labrasol and 10% PEG 200 successfully provided the maximum in vitro and ex vivo permeation and enhanced the bioavailability in the rabbits by eightfold, when compared with the marketed tablets. Conclusion: The nasal NEG is a promising novel formula for zaleplon that has higher nasal tissue permeability and enhanced systemic bioavailability.

Miconazole-loaded solid lipid nanoparticles: formulation and evaluation of a novel formula with high bioavailability and antifungal activity

Background and objective Miconazole is a broad-spectrum antifungal drug that has poor aqueous solubility (<1 µg/mL); as a result, a reduction in its therapeutic efficacy has been reported. The aim of this study was to formulate and evaluate miconazole-loaded solid lipid nanoparticles (MN-SLNs) for oral administration to find an innovative way to alleviate the disadvantages associated with commercially available capsules. Methods MN-SLNs were prepared by hot homogenization/ultrasonication. The solubility of miconazole in different solid lipids was measured. The effect of process variables, such as surfactant types, homogenization and ultrasonication times, and the charge-inducing agent on the particle size, zeta potential, and encapsulation efficiency were determined. Furthermore, in vitro drug release, antifungal activity against Candida albicans, and in vivo pharmacokinetics were studied in rabbits. Results The MN-SLN, consisting of 1.5% miconazole, 2% Precirol ATO5, 2.5% Cremophor RH40, 0.5% Lecinol, and 0.1% Dicetylphosphate, had an average diameter of 23 nm with a 90.2% entrapment efficiency. Furthermore, the formulation of MN-SLNs enhanced the antifungal activity compared with miconazole capsules. An in vivo pharmacokinetic study revealed that the bioavailability was enhanced by >2.5-fold. Conclusion MN-SLN was more efficient in the treatment of candidiasis with enhanced oral bioavailability and could be a promising carrier for the oral delivery of miconazole.

Solid lipid nanoparticles loaded with iron to overcome barriers for treatment of iron deficiency anemia.

According to the World Health Organization, 46% of the world’s children suffer from anemia, which is usually treated with iron supplements such as ferrous sulfate. The aim of this study was to prepare iron as solid lipid nanoparticles, in order to find an innovative way for alleviating the disadvantages associated with commercially available tablets. These limitations include adverse effects on the digestive system resulting in constipation and blood in the stool. The second drawback is the high variability in the absorption of iron and thus in its bioavailability. Iron solid lipid nanoparticles (Fe-SLNs) were prepared by hot homogenization/ultrasonication. Solubility of ferrous sulfate in different solid lipids was measured, and effects of process variables such as the surfactant type and concentration, homogenization and ultrasonication times, and charge-inducing agent on the particle size, zeta potential, and encapsulation efficiency were determined. Furthermore, in vitro drug release and in vivo pharmacokinetics were studied in rabbits. Results indicated that Fe-SLNs consisted of 3% Compritol 888 ATO, 1% Lecithin, 3% Poloxamer 188, and 0.2% dicetylphosphate, with an average particle size of 25 nm with 92.3% entrapment efficiency. In vivo pharmacokinetic study revealed more than fourfold enhanced bioavailability. In conclusion, Fe-SLNs could be a promising carrier for iron with enhanced oral bioavailability.

Utilization of nanotechnology to enhance percutaneous absorption of acyclovir in the treatment of herpes simplex viral infections.

This study aimed to formulate an optimized acyclovir (ACV) nanoemulsion hydrogel in order to provide a solution for the slow, variable, and incomplete oral drug absorption in patient suffering from herpes simplex viral infection. Solubility of ACV in different oils, surfactants, and cosurfactants was explored utilizing a cubic model mixture design to obtain a nanoemulsion with minimum globule size. Preparation of an optimized ACV nanoemulsion hydrogel using a three-factor, three-level Box–Behnken statistical design was conducted. The molecular weight of chitosan (X1), percentage of chitosan (X2), and percentage of Eugenol as a skin permeation enhancer (X3) were selected to study their effects on hydrogel spreadability (Y1) and percent ACV permeated through rat skin after 2.5 hours (Y2). A pharmacokinetic study of the optimized ACV nanoemulsion hydrogel was conducted in rats. Mixtures of clove oil and castor oil (3:1 ratio), Tween 80 and Span 80 (3:1 ratio), and propylene glycol and Myo-6V (3:1 ratio) were selected as the oil, surfactant, and cosurfactant phases, respectively. Statistical analysis indicated that the molecular weight of chitosan has a significant antagonistic effect on spreadability, but has no significant effect on the percent ACV permeated. The percentage of chitosan also has a significant antagonistic effect on the spreadability and percent ACV permeated. On the other hand, the percentage of Eugenol has a significant synergistic effect on percent ACV permeated, with no effect on spreadability. The ex vivo study demonstrated that the optimized ACV nanoemulsion hydrogel showed a twofold and 1.5-fold higher permeation percentage than the control gel and marketed cream, respectively. The relative bioavailability of the optimized ACV nanoemulsion hydrogel improved to 535.2% and 244.6% with respect to the raw ACV hydrogel and marketed cream, respectively, confirming improvement of the relative bioavailability of ACV in the formulated nanoemulsion hydrogel.

Optimization of caseinate-coated simvastatin-zein nanoparticles: improved bioavailability and modified release characteristics

The current study focuses on utilization of the natural biocompatible polymer zein to formulate simvastatin (SMV) nanoparticles coated with caseinate, to improve solubility and hence bioavailability, and in addition, to modify SMV-release characteristics. This formulation can be utilized for oral or possible depot parenteral applications. Fifteen formulations were prepared by liquid–liquid phase separation method, according to the Box–Behnken design, to optimize formulation variables. Sodium caseinate was used as an electrosteric stabilizer. The factors studied were: percentage of SMV in the SMV-zein mixture (X1), ethanol concentration (X2), and caseinate concentration (X3). The selected dependent variables were mean particle size (Y1), SMV encapsulation efficiency (Y2), and cumulative percentage of drug permeated after 1 hour (Y3). The diffusion of SMV from the prepared nanoparticles specified by the design was carried out using an automated Franz diffusion cell apparatus. The optimized SMV-zein formula was investigated for in vivo pharmacokinetic parameters compared with an oral SMV suspension. The optimized nanosized SMV-zein formula showed a 131 nm mean particle size and 89% encapsulation efficiency. In vitro permeation studies displayed delayed permeation characteristics, with about 42% and 85% of SMV cumulative amount released after 12 and 48 hours, respectively. Bioavailability estimation in rats revealed an augmentation in SMV bioavailability from the optimized SMV-zein formulation, by fourfold relative to SMV suspension. Formulation of caseinate-coated SMV-zein nanoparticles improves the pharmacokinetic profile and bioavailability of SMV. Accordingly, improved hypolipidemic activities for longer duration could be achieved. In addition, the reduced dosage rate of SMV-zein nanoparticles improves patient tolerability and compliance.

Intranasal in situ gel loaded with saquinavir mesylate nanosized microemulsion: Preparation, characterization, and in vivo evaluation

Saquinavir mesylate (SM) is a protease inhibitor with activity against human immunodeficiency virus type 1 (HIV-1) and is available in tablet form, which has three major problems. First, the drug undergoes extensive first pass metabolism. Second, the drug has a poor aqueous solubility. And third, it has low GIT permeability and absorption. These constrains lead to decrease oral bioavailability (4% only) and administration of large doses which increase the incidence of occurrence of the side effects. The aim of this research was to utilize nanotechnology to formulate (SM) into a nasal in situ nanosized microemulsion gel (NEG) to provide a solution for the previously mentioned problems. The solubility of (SM) in various oils, surfactants, and cosurfactants was estimated. Pseudo-ternary phase diagrams were developed and various nanosized microemulsion (NE) were prepared, and subjected to characterization, stability study, and droplet size measurements. Gellan gum was used as an in situ gelling agent. The gel strength, critical ionic concentration, gelation characteristics, in vitro release, and ex vivo nasal permeation were determined. The pharmacokinetic study was carried out in rabbits. Stable NEs were successfully developed with a droplet size range of 25-61 nm. A NEG composed of 17.5% Labrafac PG, 33% Labrasol, and 11% Transcutol HP successfully provided the maximum in vitro and ex vivo permeation, and enhanced the bioavailability in the rabbits by 12-fold when compared with the marketed tablets. It can be concluded that the nasal NEG is a promising novel formula for (SM) that has higher nasal tissue permeability and enhanced systemic bioavailability.

Statistical optimization of controlled release microspheres containing cetirizine hydrochloride as a model for water soluble drugs

Abstract The purpose was to improve the encapsulation efficiency of cetirizine hydrochloride (CTZ) microspheres as a model for water soluble drugs and control its release by applying response surface methodology. A 33 Box–Behnken design was used to determine the effect of drug/polymer ratio (X1), surfactant concentration (X2) and stirring speed (X3), on the mean particle size (Y1), percentage encapsulation efficiency (Y2) and cumulative percent drug released for 12 h (Y3). Emulsion solvent evaporation (ESE) technique was applied utilizing Eudragit RS100 as coating polymer and span 80 as surfactant. All formulations were evaluated for micromeritic properties and morphologically characterized by scanning electron microscopy (SEM). The relative bioavailability of the optimized microspheres was compared with CTZ marketed product after oral administration on healthy human volunteers using a double blind, randomized, cross-over design. The results revealed that the mean particle sizes of the microspheres ranged from 62 to 348 µm and the efficiency of entrapment ranged from 36.3% to 70.1%. The optimized CTZ microspheres exhibited a slow and controlled release over 12 h. The pharmacokinetic data of optimized CTZ microspheres showed prolonged tmax, decreased Cmax and AUC0–∞ value of 3309 ± 211 ng h/ml indicating improved relative bioavailability by 169.4% compared with marketed tablets.

Enteric-coated alendronate sodium nanoliposomes: a novel formula to overcome barriers for the treatment of osteoporosis

Background and objectives: Alendronate sodium (ALS) is the most common drug used for the treatment of osteoporosis. The challenges facing ALS use include: very poor oral bioavailability (0.6%), esophageal ulcers, and complicated instructions for its use. The objective of this research is to utilize nanotechnology to formulate ALS into enteric-coated nanoliposomes (NLS) to overcome the previously mentioned drawbacks. Methods: NLS were prepared with lipid components of phosphatidylcholine (PC), cholesterol (CH), and lecithin (Lec) in ratios 4:1:1, 4:2:1, 4:3:1, and 4:4:1, respectively. Formulas that showed the highest entrapment efficiency were prepared either alone or mixed with positive and negative charge-inducing agents and coated with Eudragit L100. Eudragit-coated NLS (EuC-NLS) were evaluated for particle size, zeta potential, morphological examination, and drug release in pH 1.2 and pH 7.4 media. The pharmacokinetic study was carried out in rabbits. Results: Spherical NLS were successfully developed with a mean size range from 70 to 150 nm. EuC-NLS with PC:CH:Lec:dicetyl phosphate (4:3:1:1) successfully resist the release of ALS in acidic environments and enhanced the bioavailability in rabbits 12-fold compared with the marketed tablets. Conclusions: EuC-NLS is a promising novel formula for ALS with higher bioavailability and a lower dose, avoiding the side effects of esophageal ulceration.