Formulation and optimization of theophylline-loaded enteric-coated spanlastic nanovesicles for colon delivery; Ameliorate acetic acid-induced ulcerative colitis.

Treatment of colon diseases presents one of the most significant obstacles to drug delivery due to the inability to deliver sufficient drug concentration selectively to the colon. The goal of the proposed study was to develop, optimize, and assess an effective colon target delivery system of theophylline-based nanovesicles (TP-NVs) surrounded by a biodegradable polymeric shell of chitosan (CS) and Eudragit L100 (EL100) for the treatment of ulcerative colitis (UC). TP-loaded nanovesicles were fabricated using the ethanol injection method and coated with CS and EL100, respectively. We used a 32-factorial design approach to optimize the concentration of CS and EL100 to minimize particle size (PS) and maximize the cumulative amount of theophylline released (CTR) after 24 h. The optimized formulation was described using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and in vitro release. In-vivo quantification of theophylline in the gastrointestinal tract and in-vivo targeting potential in a rat model of acetic acid-induced colitis were also thoroughly evaluated. The characteristics of the optimal formula predicted by the 32-factorial design approach corresponded exceptionally well with the measured PS of 271.3 nm, the zeta potential of -39.9 mV, and CTR of 3.95, and a 99.93% after 5 and 24 h, respectively. Notably, the in vivo results in the rat model of colitis showed that the formulation with an optimized coat significantly improved theophylline distribution to the colon and markedly decreased the expression of interleukin-6 and ulcerative lesions compared to a pure theophylline solution. These outcomes elucidated the feasibility of a 32-factorial design to detect the crucial interactions between the study's components. Our findings suggested that enteric-coated nanovesicles formulations with optimal coat compositions of 0.2693% (w/v) and 0.75% (w/v) of CS and EL100, respectively, were promising carriers for colonic delivery of theophylline, a rate-limiting step in the treatment of UC.

Spanlastics gel-A novel drug carrier for transdermal delivery of glimepiride.

Glimepiride (3rd-generation sulfonylurea) is used for treatment of type 2 diabetes, but its oral administration has been associated with severe gastric disturbances such as nausea, vomiting, heartburn, anorexia, haemolytic anaemia. Accordingly, the transdermal route may represent a potentially suitable alternative. This work investigates the usefulness of a novel drug carrier system for transdermal application. The system investigated were called spanlastics gels and constituted span 60 with edge activator (tween 60 or tween 80). Spanlastics gel has been introduced as a stable form alternative to the liquid formulations of spanlastics. Spanlastics gels were prepared by coacervation phase separation method. Entrapment efficiency and size of spanlastics vesicles produced from the hydration of spanlastics gels were characterised. In vitro release and skin permeation of glimepiride from various spanlastics gel formulations were investigated across mixed cellulose membrane and excised rabbit skin. The obtained results indicated that the maximum entrapment efficiency was 65.36% when the tween 60 content was 30%. The drug release and permeation were increase as the concentration of edge activator increased. Spanlastics gel prepared with Tween 80 at concentration 50% showed higher permeability and flux value (248.69 µg/cm2and 8.31 µg/cm2.h, respectively) through rabbit skin.

Synthesis and Evaluation of High Functionality and Quality Cell-penetrating Peptide Conjugated Lipid for Octaarginine Modified PEGylated Liposomes In U251 and U87 Glioma Cells.

The use of peptide ligand modified PEGylated liposomes has been widely investigated for tumor targeting. Peptides are mainly inserted in the liposomal lipid bilayer using PEG2K-lipid spacer (Peptide-PEG2K-DSPE). However, a lower cellular uptake from longer nonlinear PEG2K spacer was reported, we here synthesized a high functionality and quality (HFQ) lipid with a short, linear serine-glycine repeated peptide [(SG)5] spacer. The objective of the current study is to develop novel octaarginine (R8) peptide-HFQ lipid grafted PEGylated liposomes for glioma cells targeting. In vitro liposomes characterization showed that the mean particle size of all liposomal formulations was in the nano-scale range < 120 nm, with a small PDI value (i.e. ∼0.2) and had a spherical shape under Transmission Electron Microscope, indicating a homogenous particle size distribution. The flow cytometry in vitro cellular association data with U251 MG and U87 cells revealed that 1.5% R8-(SG)5-lipid-PEGylated liposomes exhibited significantly higher cellular association of ∼15.87 and 7.59-fold than the conventional R8-PEG2K-lipid-PEGylated liposomes (10.4 and 6.19-fold), respectively, relative to the unmodified PEGylated liposomes. Moreover, intracellular distribution studies using confocal laser scanning microscopy (CLSM) corroborated the results of the in vitro cell association. The use of ligand-HFQ-lipid liposomes could be a potential alternative to ligand-PEG2K-lipid-modified liposomes as a drug delivery system for tumor targeting.

Enhancing the Oral Bioavailability of Candesartan Cilexetil Loaded Nanostructured Lipid Carriers: In Vitro Characterization and Absorption in Rats after Oral Administration.

Candesartan Cilexetil (CC) is a prodrug widely used in the treatment of hypertension and heart failure, but it has some limitations, such as very poor aqueous solubility, high affinity to P-glycoprotein efflux mechanism, and hepatic first-pass metabolism. Therefore, it has very low oral bioavailability. In this study, glyceryl monostearate (GMS) and Capryol™ 90 were selected as solid and liquid lipids, respectively, to develop CC-NLC (nanostructured lipid carrier). CC was successfully encapsulated into NLP (CC-NLC) to enhance its oral bioavailability. CC-NLC was formulated using a hot homogenization-ultrasonication technique, and the physicochemical properties were characterized. The developed CC-NLC formulation was showed in nanometric size (121.6 ± 6.2 nm) with high encapsulation efficiency (96.23 ± 3.14%). Furthermore, it appeared almost spherical in morphology under a transmission electron microscope. The surgical experiment of the designed CC-NLC for absorption from the gastrointestinal tract revealed that CC-NLC absorption in the stomach was only 15.26% of that in the intestine. Otherwise, cellular uptake study exhibit that CC-NLCs should be internalized through the enterocytes after that transported through the systemic circulation. The pharmacokinetic results indicated that the oral bioavailability of CC was remarkably improved above 2-fold after encapsulation into nanostructured lipid carriers. These results ensured that nanostructured lipid carriers have a highly beneficial effect on improving the oral bioavailability of poorly water-soluble drugs, such as CC.

Formulation and optimization of drug-loaded mesoporous silica nanoparticle-based tablets to improve the dissolution rate of the poorly water-soluble drug silymarin.

Porous carriers have been put forward as a promising alternative for stabilizing the amorphous state of loaded drugs, and thus significantly improving the dissolution rate of poorly soluble compounds. The purpose of this study was to enhance the saturation solubility, dissolution rate and drug loading of the poorly water-soluble drug silymarin via incorporation into mesoporous silica nanospheres within a lyophilized tablet to obtain a unique formulation. 32 full factorial design was applied to study the effect of both independent variables, polyvinyl alcohol (PVA) as stabilizer and binder and sucrose as cryoprotectant and disintegrant; and on the dependent variables that included the mean particle size (Y1), disintegration time (Y2), tablet strength (Y3) and % of drug release after 2 min, R2min,Y4. The drug-loaded mesoporous silica nanospheres and the optimized formula was evaluated by different characterization methods: scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, X-ray diffractometry and Fourier transform infrared spectroscopy; as well as drug content, saturation solubility and moisture content. The evaluation demonstrated that the loaded mesoporous silica nanospheres and the optimized formula are in amorphous state without any chemical interaction with the silica matrix or the stabilizer. Moreover, the drug was stably maintained in nanosize range with narrow particle size distribution. Furthermore, the optimized lyophilized tablets had highly porous structure, low friability (less than 1%), fast disintegration (less than 30 s), high tablet strength, low moisture content (less than 1%), remarkably increased dissolution rate and noticeable improvement in saturation solubility.

Real-Time Label-Free Targeting Assessment and in Vitro Characterization of Curcumin-Loaded Poly-lactic-co-glycolic Acid Nanoparticles for Oral Colon Targeting.

The exploitation of curcumin for oral disease treatment is limited by its low solubility, poor bioavailability, and low stability. Surface-functionalized poly-lactic-co-glycolic acid (PLGA) nanoparticles (NPs) have shown promising results to ameliorate selective delivery of drugs to the gastro-intestinal tract. In this study, curcumin-loaded PLGA NPs (C-PLGA NPs) of about 200 nm were surface-coated with chitosan (CS) for gastro-intestinal mucosa adhesion, wheat germ agglutinin (WGA) for colon targeting or GE11 peptide for tumor colon targeting. Spectrometric and zeta potential analyses confirmed the successful functionalization of the C-PLGA NPs. Real-time label-free assessment of the cell membrane-NP interactions and NP cell uptake were performed by quartz crystal microbalance coupled with supported lipid bilayers and by surface plasmon resonance coupled with living cells. The study showed that CS-coated C-PLGA NPs interact with cells by the electrostatic mechanism, while both WGA- and GE11-coated C-PLGA NPs interact and are taken up by cells by specific active mechanisms. In vitro cell uptake studies corroborated the real-time label-free assessment by yielding a curcumin cell uptake of 7.3 ± 0.3, 13.5 ± 1.0, 27.3 ± 4.9, and 26.0 ± 1.3 µg per 104 HT-29 cells for noncoated, CS-, WGA-, and GE11-coated C-PLGA NPs, respectively. Finally, preliminary in vivo studies showed that the WGA-coated C-PLGA NPs efficiently accumulate in the colon after oral administration to healthy Balb/c mice. In summary, the WGA- and GE11-coated C-PLGA NPs displayed high potential for application as active targeted carriers for anticancer drug delivery to the colon.

Formulation and optimization of lyophilized nanosuspension tablets to improve the physicochemical properties and provide immediate release of silymarin.

Silymarin (SLM) is a hepatoprotective herbal drug characterized by low aqueous solubility and, consequently, low oral bioavailability. The objective of this study was to enhance the physiochemical properties of SLM, through preparation and optimization of lyophilized nanosuspension tablets (LNTs). LNTs were prepared by sonoprecipitation technique followed by a freeze-drying process using both polyvinyl alcohol (PVA) as stabilizer and binder, and mannitol as cryoprotectant and disintegrating agent. 32 full factorial design (FFD) was applied to study the effect of independent variables at different concentrations of both PVA (X1) and mannitol (X2) on the dependent variables that included mean particle size (Y1), disintegration time (Y2), friability % (Y3) and time required to release 90% of the drug (Y4). Several physicochemical evaluations were implemented on the optimized formula; for instance differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. These analyses demonstrated that the drug was in an amorphous state, stable in nanosize range and displayed no chemical interaction with the polymer. Moreover, the optimized formula had highly porous structure, rapid disintegration, friability with less than 1% and noticeable improvement in saturation solubility and dissolution rate.

In vitro and in vivo evaluation of cyclodextrin-based nanosponges for enhancing oral bioavailability of atorvastatin calcium.

The aim of this study was to explore the feasibility of complexing the poorly water-soluble drug atorvastatin calcium (AC) with ß-cyclodextrin (ß-CD) based nanosponges (NS), which offer advantages of improving dissolution rate and eventually oral bioavailability. Blank NS were fabricated at first by reacting ß-CD with the cross-linker carbonyldiimidazole at different molar ratios (1:2, 1:4, and 1:8), then NS of highest solubilization extent for AC were complexed with AC. AC loaded NS (AC-NS) were characterized for various physicochemical properties. Pharmacokinetic, pharmacodynamics and histological finding of AC-NS were performed in rats. The prepared AC-NS showed particles size ranged from 408.7 ± 12.9 to 423 ± 15.9 nm while zeta potential values varied from -21.7 ± 0.90 to -22.7 ± 0.85 mV. The loading capacity varied from 17.9 ± 1.21 to 34.1 ± 1.16%. DSC, FT-IR, and PXRD studies confirmed the complexation of AC with NS and amorphous state of the drug in the complex. AC-NS displayed a biphasic release pattern with increase in the dissolution rate of AC as compared to plain AC. Oral administration of AC-NS (1:4 w/w, drug: NS) to rats led to 2.13-folds increase in the bioavailability as compared to AC suspension. Pharmacodynamics studies in rats with fatty liver revealed significant reduction (p < .05) in total cholesterol, triglyceride, LDL-C and increased level of beneficial HDL-C along with improvement in the associated liver steatosis as confirmed through photomicrographs of liver sections. In this study, we confirmed that complexation of AC with NS would be a viable approach for improving oral bioavailability and in vivo performance of AC.

Optimization of self-nanoemulsifying systems for the enhancement of in vivo hypoglycemic efficacy of glimepiride transdermal patches.

OBJECTIVES: To optimize and use of glimepiride (GMD)-loaded self-nanoemulsifying delivery systems (SNEDs) for the preparation of transdermal patches. METHODS: Mixture design was utilized to optimize GMD-loaded SNEDs in acidic and aqueous pH media. Optimized GMD-loaded SNEDs were used in the preparation of chitosan (acidic) and hydroxypropyl methyl cellulose (HPMC) (aqueous) films. The prepared optimized formulations were investigated for ex vivo skin permeation, for in vivo hypoglycemic activity and for their pharmacokinetic parameters using animal model. RESULTS: The optimized formulations showed flux value of (2.88 and 4.428 µg/cm(2)/h) through rat skin for chitosan and HPMC films, respectively. The pattern of GMD release from both formulations was in favor of Higuchi and approaching zero order models. The n values for Korsmeyer-Peppas equation were characteristic of anomalous (non-Fickian) release mechanism. Moreover, HPMC patches have shown significant reductions (p < 0.05) in blood glucose levels; (213.33 ± 15.19) mg/100 ml from the base-line measurement after 12 h of application. CONCLUSIONS: Optimized GMD SNEDs patches were found to improve GMD skin permeability and the essential pharmacokinetic parameters. Further extensive pre/clinical studies are necessary prior to use transdermal GMD as a valuable alternative to peroral dosage forms with improved bioavailability, longer duration of action and more patient convenience.

Influence of various concentrations of terpene-4-ol enhancer and carbopol-934 mucoadhesive upon the in vitro ocular transport and the in vivo intraocular pressure lowering effects of dorzolamide ophthalmic formulations using albino rabbits.

The objectives of the current study are (i) to maximize the ocular bioavailability of dorzolamide hydrochloride (DZD) through; (a) enhancement of the DZD corneal transport using various concentrations of selected natural terpene-4-ol enhancers, (b) increasing the contact time of the drug with the absorbing tissues of the eye using selected carbopol-934 (C-934) as mucoadhesive to reduce the extensive pre-corneal loss of the installed dose due to the physiologically normal fast tear-washout, and (ii) to assess the in vivo intraocular pressure (IOP) lowering effects of the gel test formulations using normotensive New Zealand albino rabbits. In this study, DZD was formulated as 2% formulations ophthalmic gels containing different concentrations of C-934 as mucoadhesive, as well as, with various concentrations of terpene-4-ol as a natural corneal penetration enhancers. The transport of DZD from the gel formulations was quantitatively determined using in vitro diffusion experiments. The permeability parameters of DZD were calculated employing the most appropriate mathematical equations. Further, the in vivo IOP lowering effects of the test formulations were also assessed using the TONO-PEN(R)XL applanation tonometer in normotensive New Zealand albino rabbits. The overall results revealed that there is a direct correlation between both the in vitro permeability parameters and the contact period with the ocular tissues and the in vivo DeltaIOP. In such case, the in vitro permeability parameters of DZD could be used as a determinant for the in vivo IOP measurements. The magnitude of the DZD-IOP lowering effects as well as the durations of actions for the test formulations has been found to be greatly dependent upon (a) the concentration of the terpene-4-ol corneal penetration enhancer and (b) the duration of contact period with the ocular tissues, which was found to be a single-valued function of the C-943 mucoadhesive concentration.

Preparation and characterization of demeclocycline liposomal formulations and assessment of their intraocular pressure-lowering effects.

UNLABELLED: The objective of the present study is to enhance the ocular permeability and to study the ocular disposition of demeclocycline (DEM), liposomal topical formulation for treatment of elevated intraocular pressure using Male New Zealand albino rabbits as an animal model. METHODS: Different liposomal formulations of the DEM were prepared and characterized for their drug entrapment, drug-liposome affinity and the in vivo distribution of DEM in various ocular tissues. Liposomal formulations of promising drug distribution within the various ocular tissues have been scaled up for the in vivo intraocular pressure (IOP) measurements by Pneuma-tonometer using different dosing regimens. RESULTS: The amounts of drug entrapped in the charged liposomal formulations were comparable and lower than that entrapped with neutral ones. DEM was found to be more concentrated (69-95%) in the lipid phase of the liposome. The concentrations of DEM in the cornea, aqueous humor, and conjunctiva were 4.76, 2.18, and 23.32 microg/g of tissue, respectively. Test formulations have shown significant reductions in the IOP on using different treatment protocols. CONCLUSION: Preparation of liposomal formulations of DEM has substantially enhanced its transcorneal transport. Furthermore, the test formulations have shown promising and long-lasting intraocular pressure-lowering effect comparable with that of pilocarpine formulation as a control.

Percutaneous permeation of enantiomers and racemates of chiral drugs and prediction of their flux ratios using thermal data: a pharmaceutical perspective.

Albeit pharmacological, pharmacokinetic, and toxicological differences between enantiomeric pairs or between the pure enantiomers and racemate of chiral drugs are known to exist for decades, we are just beginning to realize that there are apparent differences between these species with respect to their percutaneous permeation as well. Such differences in permeation are likely to be enhanced when chiral drugs are formulated with chiral excipients, necessitating a careful assessment of the effect of formulation excipients on the permeation as well as the overall therapeutic outcomes. The in vitro transport data from the preclinical investigations, using laboratory animal models and/or in vitro cell culture systems, must be carefully validated in vivo as there are differences between these models and the human skin. Mathematical models such as MTMT that utilize the interdependence of certain physicochemical characteristics and percutaneous permeability have a predictive value in assessing the flux behavior of enantiomers and racemates.

Effect of Azone upon the in vivo antiviral efficacy of cidofovir or acyclovir topical formulations in treatment/prevention of cutaneous HSV-1 infections and its correlation with skin target site free drug concentration in hairless mice.

The purpose of this study is to examine the influence of Azone upon the skin target site free drug concentration (C(*)) and its correlation with the in vivo antiviral efficacies of cidofovir (HPMPC) and acyclovir (ACV) against HSV-1 infections. Formulations of HPMPC and ACV with or without Azone were used. The in vitro skin flux experiments were performed and the C(*) values were calculated. For the in vivo efficacy studies, hairless mice cutaneously infected with HSV-1 were used and three different treatment protocols were carried out. The protocols were chosen based upon when therapy is initiated and terminated in such a way to assess the efficacy of the test drug to cure and/or prevent HSV-1 infections. A finite dose of the formulation was topically applied twice a day for the predetermined time course for each protocol and the lesions were scored on the fifth day. For ACV formulation with Azone, the C(*) values and hence the in vivo efficacy were much higher than those for that without Azone. In protocol #1, however, early treatment did not increase the in vivo efficacy of ACV when compared with the standard treatment protocol #3. In protocol #2 where the treatment was terminated on the day of virus inoculation, the efficacies for both ACV formulations were completely absent. Although the estimated C(*) values for HPMPC formulations with and without Azone were comparable, formulation with Azone was much more effective than that without Azone in all treatment protocols. HPMPC formulations with Azone at similar flux values were much more effective in "treating and preventing" HSV-1 infections than those without Azone. For ACV formulations, in contrast, addition of Azone has failed to show any effect on the preventive in vivo antiviral efficacy and the enhancement of ACV in vivo antiviral efficacy was merely the skin permeation enhancement effect of Azone.