Rihab Osman

Chitosan and cyclodextrin in intranasal microemulsion for improved brain buspirone hydrochloride pharmacokinetics in rats

The aim of this study was to develop buspirone hydrochloride microemulsion formulations for intranasal administration to improve the drug bioavailability and provide high drug brain levels. For the purpose, chitosan aspartate, and hydroxypropyl-β-cyclodextrin were incorporated in the microemulsions. The prepared formulations were characterized. Biological investigations including pharmacokinetic studies, brain drug targeting efficiency determinations and histopathological examinations were performed on rats. The results showed that safe and stable mucoadhesive microemulsion suitable for nasal administration were successfully prepared. Ex vivo drug permeation revealed high drug permeation from microemulsions. Absolute bioavailability after intranasal administration of buspirone mucoadhesive microemulsion increased significantly and plasma concentration peaked at 15 min. The AUC0-360(brain) was 3 times that obtained after intravenous administration. A high brain targeting efficiency (86.6%) and a direct nose to brain transport (88%) confirmed the direct nose to brain transport of buspirone following nasal administration of the microemulsions.

Lecithin/TPGS-based spray-dried self-microemulsifying drug delivery systems: In vitro pulmonary deposition and cytotoxicity.

The aim of the present work was to develop a new solid self-microemulsifying drug delivery system (SMEDDS) for the pulmonary delivery of the poorly water-soluble anti-cancer drug atorvastatin (AVT). Microemulsion (ME) was first developed using isopropyl myristate (IPM), a combination of 2 biocompatible surfactants: lecithin/d-α-tocopheryl polyethylene glycol succinate (TPGS) and ethanol as co-surfactant. Two types of lecithin with different phosphatidylcholine (PC) contents were compared. Phase diagram, physico-chemical characterization and stability studies were used to investigate ME region. Solid SMEDDS were then prepared by spray-drying the selected ME using a combination of carriers composed of sugars, leucine as dispersibility enhancer with or without polyethylene glycol (PEG) 6000. Yield, flow properties, particle size and in vitro pulmonary deposition were used to characterize the spray-dried powders. Reconstituted MEs were characterized in terms of morphology, particle size and size distribution. In vitro cytotoxicity study was undertaken on lung cancer cell line for the selected MEs and SD-SMEDDS formulae. Results showed that the most satisfactory MEs properties were obtained with 1:3 lecithin/TPGS, 1:1 lecithin/oil and 1:1 surfactant/co-surfactant ratios. A larger ME area was obtained with lecithin containing 100% PC compared to the less expensive lecithin containing 20% PC. By manipulating spray drying parameters, carrier composition and ratio of ME lipids to carrier, microparticles with more than 70% of respirable fraction could be prepared. The ME was efficiently recovered in simulated lung fluid even after removal of alcohol. The concurrent delivery of AVT with TPGS in solid SMEDDS greatly enhanced the cytotoxic activity on lung cancer cells.

Low molecular weight heparins for current and future uses: approaches for micro- and nano-particulate delivery

Abstract Low molecular weight heparins (LMWHs), the anticoagulant drug of choice in many indications, had been suggested as novel drug treatment for a range of diseases. Their superior pharmacokinetic properties compared to unfractionated heparin (UFH), motivated scientists to explore new delivery systems for improved therapeutic outcomes. Micro- and nano-carriers, with the versatile nature and characteristics of materials used for their fabrication, are able to surmount the challenges opposed by their native structures. The present review discusses the recent perspectives on the development of micro- and nano-particulate vectors for the delivery of LMWHs through various routes. Special focus on the application of the suggested systems, their characterization and the achieved improved bioavailability will be given throughout the review.

Nasal polysaccharides-glucose regulator microparticles: optimization, tolerability and antidiabetic activity in rats.

The aim of the present study was to load the post-prandial glucose regulator, repaglinide (REP), on spray dried mucoadhesive microparticles (MPs) comprising anionic polysaccharides. The formulation parameters of the polysaccharides-REP spray dried powders (SDP) namely, polysaccharide type and drug to polymer (D/P) ratio, were optimized for % release after 5 min (R%5 min) and time required for 80% release (T80%). The suitability of the selected formulae for nasal application was evaluated by ex vivo mucoadhesion, in vitro cytocompatability and tolerability studies. A pharmacodynamic study in diabetic rats was conducted. Results showed that both polysaccharide type and amount greatly influenced the chosen responses. REP was highly incorporated in mucoadhesive MPs with proven safety on the rat nasal mucosa. The selected REP loaded powders exhibited a significant two to threefold increase in total decrease in blood glucose compared to the nasal and intravenous solutions.

Novel Heat-Stable Enterotoxin (STa) Immunogen Based on Cationic Nanoliposomes: Preparation, Characterization and Immunization

The novelties encountered in the field of formulation have provided promising solutions for the problematic vaccine development of hapten molecules. In the current study, the novel preparation of a cationic nanoliposomal immunogen of the heat stable enterotoxin (STa) was reported. STa was produced from clinically ETEC isolate of diarrheic neonatal calves and purified using RP-HPLC. STa was loaded into the cationic vesicles which were characterized for their particle size, surface charge, morphology, STa loading, and stability. The STa loaded cationic nanoliposome was used for mice immunization and the generation of STa antibody was monitored using ELISA. Results displayed the spherical nature of the STa loaded vesicles, their suitable size and homogeneity represented by a particle size of 228.1 nm and a PDI of 0.202. The surface charge of the STa nanoliposomes was +29.9, demonstrating sufficient stability during refrigeration storage. The STa loaded cationic nanoliposome was able to elicit specific STa antibody response, and to confer effective protection against STa challenge in mice. The STa antibody binding titer and neutralization capacity were 105 and 104 mouse units/ml serum, respectively. The developed system is a one-step procedure, which overcomes the disadvantage of the complexity of generation of the hapten-carrier conjugate. In conclusion, the developed STa-cationic nanoliposomal immunogen is feasible and has the potential to improve effectiveness against ETEC, suggesting its applicability in preventing the harmful effects of ETEC infection in neonatal calves.

Polysaccharides-based nanocomplexes for the prolonged delivery of enoxaparin: In-vitro and in-vivo evaluation

Thromboprophylaxis and anticoagulant therapy face serious medical challenges in terms of how crucial it is to maintain therapeutic activity of the anticoagulant agent over the required period of time. Failure to do so will lead to an increased risk of clot propagation if a subtherapeutic drug level is reached. On the other hand, higher-than intended anticoagulation levels might lead to an enhanced risk of hemorrhagic complications. Nanocomplexes (NCs) for the controlled delivery of the antithrombotic Enoxaparin (Enox) with dextran sulfate (DS) and chitosan (CS) were formulated, in an attempt to circumvent therapeutic and compliance challenges associated with the prolonged administration of the current dosage form. Using polyelectrolyte complexation method, various fabrication and formulation parameters were tested. Assessment of ex-vivo stability of selected formulae in rat serum was done prior to determination of their pharmacokinetic profile. High EE% was achieved in all systems prepared. In absence of DS, target size was obtained when 0.54mg/mL CS at an initial pH of 5 and Enox to CS mass ratio of 1:2.5 were employed at room temperature. These parameters were shifted to new optima upon introduction of DS. The anticoagulant activity of NCs (in absence/presence of DS) was significantly sustained compared to the market product (135 and >144h versus 5h, respectively).

Dextran-based Nanocarriers for Delivery of Bioactives

BACKGROUND Dextran (DX) is a natural polysaccharide produced in the laboratory by fermentation of sucrose under the effect of the enzyme DX sucrase (1,6-α-D-glucan-α- glucosyltransferase). After harvesting and purification DX is subjected to cracking and separation to obtain the desired molecular weight. METHODS The hydroxyl groups present in DX offer many sites for derivatization allowing the production of functionalized glycoconjugates biocompatible compound. DX and its derivatives are getting increased attention for use in core decoration or as carriers in novel drug delivery systems. This includes, among others, ion-pairing, self-aggregate, protein and drug conjugates. DX carriers and camouflaged particles will be dealt with in this review to give emphasis on the great versatility of this natural biocompatible polysaccharide. CONCLUSION With the continuous development in the area of drug delivery, we believe that the unique properties of this versatile nanocarrier platform will elect it as one of the cornerstones of safe nanodelivery systems.

Defining cisplatin incorporation properties in thermosensitive injectable biodegradable hydrogel for sustained delivery and enhanced cytotoxicity

Injectable thermoreversible chitosan (CS)/β-glycerophosphate (β-GP) hydrogels were developed for prolonged localized delivery of cisplatin (Cis). The effects of formulation variables on the thermoreversible hydrogels preparation as well as the impact of drug incorporation method on Cis release were studied. Antitumor activity of Cis CS/β-GP thermoreversible hydrogels were evaluated against HCT-116 human colorectal cancer cells and MCF-7 human breast cancer cells. Incorporation of Cis to CS solution adjusted at pH 6.2 prior to hydrogel preparation deemed necessary to achieve a sustained release up to 4 days. Cis loaded CS/β-GP thermoreversible hydrogels showed enhanced antitumor activity with about 1.2 fold and 2.05 fold that of Cis solution against HCT-116 cancer cells and MCF-7 cancer cells respectively. The obtained enhanced antitumor activity elected this delivery system for further in vivo and toxicological investigations.

Nanocomplexes of an insulinotropic drug: optimization, microparticle formation, and antidiabetic activity in rats

The aim of the present work was to test the ability of two non-diabetogenic carbohydrates to intranasally deliver the insulinotropic drug repaglinide (REP) for controlling blood glucose level. REP was loaded onto chitosan/alginate nanocomplexes (NCs) suitable for mucosal delivery and uptake. Improved stability and delivery characteristics were obtained by spray drying the selected NCs, yielding microparticles. A statistical experimental design was adopted to investigate the effects of the formulations’ variables on two critical responses: NC size and drug entrapment efficiency. Physicochemical characterizations of the network’s structures were done, and in vitro cytotoxicity and histopathological studies were conducted. The potential of the developed system to prolong the drug effect was tested on diabetic rats. The results showed that to attain particles suitable for nasal delivery, alginate should be used at its lowest level used in this study (0.6 mg/mL). A low level of chitosan (0.5 mg/mL) was needed when the drug was cation-loaded, while the high chitosan level (1 mg/mL) was more suitable when REP was anion-loaded. The best entrapment efficiency was achieved at a theoretical drug loading of 0.025 mg/mL. Discrete NCs could be rapidly recovered from the spray-dried microparticles. The cytotoxicity and histopathological studies indicated that such formulations were well tolerated. The antihyperglycemic activity of the nasally administered formulae was gradual but was significantly sustained over 24 hours, suggesting NC mucosal uptake. Nasal delivery of such dry powders achieved better glycemic control compared with the conventional oral tablets.

Construction and immunogenicity analysis of nanoparticulated conjugate of heat-stable enterotoxin (STa) of enterotoxigenic Escherichia coli

The ultimate goal of this research was to overcome the low immunogenicity of the biological macromolecule (heat stable enterotoxin STa) via its conjugation to biodegradable PLGA nanoparticles (NP). STa was first isolated from Enterotoxigenic Escherichia coli (ETEC), purified and identified using reported HPLC procedures. Optimized homogenous PLGA NP, prepared using the nanoprecipitation technique were used for conjugating STa using the carbodiimide synthesis. Covalent binding of STa to PLGA NP was confirmed via FTIR and 1HNMR analysis. Safety and tolerability of the developed nanoparticulated STa-PLGA conjugate were confirmed by MTT assay on A549 lung cancer cells. After subcutaneous immunization, STA-PLGA NP conjugate induced a significant immune response in mice showing a strong binding and neutralizing antibody titer. The developed novel STa-PLGA NP conjugate is expected to provide promising protection against enterotoxigenic Escherichia coli (ETEC).