Nazik A. Elgindy

Albumin-based nanoparticles as potential controlled release drug delivery systems

Albumin, a versatile protein carrier for drug delivery, has been shown to be nontoxic, non-immunogenic, biocompatible and biodegradable. Therefore, it is ideal material to fabricate nanoparticles for drug delivery. Albumin nanoparticles have gained considerable attention owing to their high binding capacity of various drugs and being well tolerated without any serious side-effects. The current review embodies an in-depth discussion of albumin nanoparticles with respect to types, formulation aspects, major outcomes of in vitro and in vivo investigations as well as site-specific drug targeting using various ligands modifying the surface of albumin nanoparticles with special insights to the field of oncology. Specialized nanotechnological techniques like desolvation, emulsification, thermal gelation and recently nano-spray drying, nab-technology and self-assembly that have been investigated for fabrication of albumin nanoparticles, are also discussed. Nanocomplexes of albumin with other components in the area of drug delivery are also included in this review.

Protein-based nanocarriers as promising drug and gene delivery systems

Among the available potential colloidal drug carrier systems, protein-based nanocarriers are particularly interesting. Meeting requirements such as low cytotoxicity, abundant renewable sources, high drug binding capacity and significant uptake into the targeted cells, protein-based nanocarriers represent promising candidates for efficient drug and gene delivery. Moreover, the unique protein structure offers the possibility of site-specific drug conjugation and targeting using various ligands modifying the surface of protein nanocarriers. The current review highlights the main advances achieved in utilizing protein nanocarriers as natural vehicles for drug and gene delivery tasks with respect to types, advantages, limitations, formulation aspects as well as the major outcomes of the in vitro and in vivo investigations. The recently emerged technologies in the formulation of protein nanocarriers including using recombinant proteins as alternatives to native ones and new non-toxic crosslinkers as alternatives to the toxic chemical crosslinkers are also discussed.

Casein-based formulations as promising controlled release drug delivery systems

Casein, the major milk protein, forms an integral part of the daily diet in many parts of the world. Casein possesses a number of interesting properties that make it a good candidate for conventional and novel drug delivery systems. This article reviews approaches aimed to associate bioactive molecules to casein and analyze the evidence of their efficacy in modifying the release and/or improving the bioavailability of the associated molecules. The ability of casein to modify drug dissolution from compacts was reported. The high tensile strength of casein films, favors its use as an acceptable film-coating for tablets. Naturally occurring genipin and a natural tissue enzyme, transglutaminase, were used as crosslinkers to prepare novel casein-based hydrogels for the controlled release of bioactives. Casein floating beads were developed to increase the residence time of drugs in the stomach based on its emulsifying and bubble-forming properties. Casein-based microparticles entrapping bioactive molecules were prepared via emulsification-chemical crosslinking with glutaraldehyde, enzymatic crosslinking by transglutaminase, simple coacervation and electrostatic complexation. Casein nano-formulations were also prepared to deliver nutraceuticals and synthetic drugs via enzymatic crosslinking, graft copolymerization, heat-gelation and polyelectrolyte ionic complexation. It can be concluded that casein-based formulations are promising materials for controlled drug delivery.

Spray-dried casein-based micelles as a vehicle for solubilization and controlled delivery of flutamide: Formulation, characterization, and in vivo pharmacokinetics

Novel casein (CAS)-based micelles loaded with the poorly soluble anti-cancer drug, flutamide (FLT), were successfully developed in a powdered form via spray-drying technique. Genipin (GNP) was used to crosslink CAS micelles as demonstrated by color variation of the micelles. Drug solubilization was enhanced by incorporation within the hydrophobic micellar core which was confirmed by solubility study and UV spectra. Spherical core-shell micelles were obtained with a particle size below 100 nm and zeta potential around -30 mV. At low drug loading, FLT was totally incorporated within micellar core as revealed by thermal analysis. However, at higher loading, excess non-incorporated drug at micelle surface caused a significant reduction in the surface charge density. Turbidity measurements demonstrated the high physical stability of micelles for 2 weeks dependent on GNP-crosslinking degree. In a dry powdered form, the micelles were stable for 6 months with no significant changes in drug content or particle size. A sustained drug release from CAS micelles up to 5 days was observed. After i.v. administration into rats, CAS micelles exhibited a prolonged plasma circulation of FLT compared to drug solution. Furthermore, a more prolonged drug systemic circulation was observed for GNP-crosslinked micelles. Overall, this study reports the application of spray-dried natural protein-based micelles for i.v. delivery of hydrophobic anti-cancer drugs such as FLT.

Novel ionically crosslinked casein nanoparticles for flutamide delivery: formulation, characterization, and in vivo pharmacokinetics.

A novel particulate delivery matrix based on ionically crosslinked casein (CAS) nanoparticles was developed for controlled release of the poorly soluble anticancer drug flutamide (FLT). Nanoparticles were fabricated via oil-in-water emulsification then stabilized by ionic crosslinking of the positively charged CAS molecules below their isoelectric point, with the polyanionic crosslinker sodium tripolyphosphate. With the optimal preparation conditions, the drug loading and incorporation efficiency achieved were 8.73% and 64.55%, respectively. The nanoparticles exhibited a spherical shape with a size below 100 nm and a positive zeta potential (+7.54 to +17.3 mV). FLT was molecularly dispersed inside the nanoparticle protein matrix, as revealed by thermal analysis. The biodegradability of CAS nanoparticles in trypsin solution could be easily modulated by varying the sodium tripolyphosphate crosslinking density. A sustained release of FLT from CAS nanoparticles for up to 4 days was observed, depending on the crosslinking density. After intravenous administration of FLT-CAS nanoparticles into rats, CAS nanoparticles exhibited a longer circulation time and a markedly delayed blood clearance of FLT, with the half-life of FLT extended from 0.88 hours to 14.64 hours, compared with drug cosolvent. The results offer a promising method for tailoring biodegradable, drug-loaded CAS nanoparticles as controlled, long-circulating drug delivery systems of hydrophobic anticancer drugs in aqueous vehicles.

Lyophilization monophase solution technique for improvement of the physicochemical properties of an anticancer drug, flutamide

Flutamide (FLT), an anticancer drug for prostatic carcinoma, has poor aqueous solubility and low oral bioavailability. This study describes the ability of beta-cyclodextrin (betaCD) and hydroxypropyl-beta-cyclodextrin (HPbetaCD) to form complexes with flutamide with enhanced solubility and dissolution rate in vitro. FLT-CD lyophilized dispersions (LDs) were prepared via lyophilization monophase solution technique using tertiary butyl alcohol (TBA) as a cosolvent. FLT showed an A(L)-type phase solubility diagram consistent with a linear increase in drug solubility as a function of CD concentration. Gas chromatography indicated that the LDs contain 0.02-0.03% w/w residual TBA. Based on the data from differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), FLT was fully amorphous in 1:5 FLT-HPbetaCD LD as indicated by complete disappearance of FLT endothermic and diffraction peaks. The Fourier transform infrared (FTIR) spectra indicated that a FLT-CD interaction took place in the lyophilized complex. The particle sizes of 1:1 FLT-betaCD and FLT-HPbetaCD LDs were 0.92 and 0.82microm, with a high surface area (484.55 and 705.68m(2)/g) and porosity (769.46 and 1020.99e(-3)ml/g), respectively. The dissolution rate of FLT from its CD complexes was enhanced significantly. After 30min in 0.1N HCl, about 73% and 86% of FLT were dissolved from 1:5 FLT-betaCD and FLT-HPbetaCD LDs, respectively, compared to only 13.45% of pure drug. No endothermic peak corresponding to FLT melting was detected in 1:5 FLT-HPbetaCD LD after storage at 20 degrees C and 45% relative humidity for 90days thus indicating the stability of this binary system. These data suggest that cyclodextrins might be useful adjuncts in preparation of immediate-release formulations of FLT.

Respirable nanocarriers as a promising strategy for antitubercular drug delivery

Tuberculosis is considered a fatal respiratory infectious disease that represents a global threat, which must be faced. Despite the availability of oral conventional anti-tuberculosis therapy, the disease is characterized by high progression. The leading causes are poor patient compliance and failure to adhere to the drug regimen primarily due to systemic toxicity. In this context, inhalation therapy as a non-invasive route of administration is capable of increasing local drug concentrations in lung tissues, the primary infection side, by passive targeting as well as reducing the risk of systemic toxicity and hence improving the patient compliance. Nanotechnology represents a promising strategy in the development of inhaled drug delivery systems. Nanocarriers can improve the drug effectiveness and decrease the expected side effects as consequences of their ability to target the drug to the infected area as well as sustain its release in a prolonged manner. The current review summarizes the state-of-the-art in the development of inhaled nanotechnological carriers confined currently available anti-tuberculosis drugs (anti TB) for local and targeting drug delivery specifically, polymeric nanoparticles, solid lipid nanoparticles, nanoliposomes and nanomicelles. Moreover, complexes and ion pairs are also reported. The impact and progress of nanotechnology on the therapeutic effectiveness and patient adherence to anti TB regimen are addressed.

Biopolymeric Nanoparticles for Oral Protein Delivery: Design and In Vitro Evaluation

Chitosan (CS) nanoparticles for the oral delivery of the protein, Human Serum Albumin (HSA) were prepared by two techniques (precipitation and ionic gelation) together with two anions (sodium sulfate or tripolyphosphate, TPP). HSA was loaded with CS nanoparticles by adsorption or entrapment loading protocols. The highest HSA association efficiency (93.43%) and loading capacity (58.65%) were obtained using ionic gelation technique with 0.1% w/v TPP as a crosslinker. The particle size of CS-HSA nanoparticles ranged between 100-320 nm with a high specific surface area (703-903 m 2 /g) and porosity (1060.99-1350.95 e -3 ml/g). Incubation of nanoparticles with lysozyme led to a reduction of 243 nm in particle size within 3 h. CS nanoparticles was redispersible after one month storage. CS/TPP nanoparticles prepared by precipitation/protein entrapment technique slowly released 10.34% HSA over 5 days which is suitable for vaccine or protein delivery while 86.54% of HSA was released from nanoparticles prepared by precipitation/ protein adsorption technique after 8 hr which is suitable for rapid drug release. Using ionic gelation technique, CS/ TPP nanoparticles released 22.47-38.65 % HSA over 5 days at 7:1 to 3:1 CS/TPP mass ratio, respectively. Both techniques retained the structural integrity of HSA after preparation and release processes which was proven via gel electrophoresis.

Ionically-crosslinked milk protein nanoparticles as flutamide carriers for effective anticancer activity in prostate cancer-bearing rats

In this study, casein (CAS) nanoparticles were used to encapsulate the hydrophobic anticancer drug, flutamide (FLT), aiming at controlling its release, enhancing its anti-tumor activity, and reducing its hepatotoxicity. The nanoparticles were prepared by emulsification of CAS, at pH below its isoelectric point, and stabilized via ionic-crosslinking with sodium tripolyphosphate (TPP). The nanoparticles were spherical and positively charged with a size below 100 nm and exhibited a sustained drug release up to 4 days. After intravenous administration into prostate cancer-bearing rats for 28 days, FLT-loaded CAS nanoparticles showed a higher anti-tumor efficacy as revealed by a significantly higher % reduction in PSA serum level (75%) compared to free FLT (55%). Moreover, the nanoparticles demonstrated a marked reduction in the relative weights of both prostate tumor and seminal vesicle (43% and 32%) compared to free FLT (12% and 18%), respectively. A significantly higher anti-proliferative, anti-angiogenic, and apoptotic effects was demonstrated by the nanoparticles compared to drug solution as evidenced by their ability to decrease the expression of the proliferative marker (Ki-67) and reduce the level of tumor angiogenic markers (VEGF and IGF-1) as well as their ability to activate caspase-3 with subsequent induction of apoptosis in prostate cancer cells. Conclusively, these novel ionically-crosslinked milk protein nanovehicles offer a promising carrier to allow controlled intravenous delivery of hydrophobic anticancer drugs.

Swellable floating tablet based on spray-dried casein nanoparticles: Near-infrared spectral characterization and floating matrix evaluation.

In this study, spray-dried alfuzosin hydrochloride (ALF)-loaded casein (CAS) nanoparticles were successfully used for the preparation of a swellable floating matrix via direct compression. The developed NIR calibration model was able to assess ALF and CAS levels in five different batches of drug-loaded nanoparticles. The calibration and prediction plots exhibited good linearity with correlation coefficients of more than 0.9. The standard error of calibration and cross-validation was less than 5% of the measured values, confirming the accuracy of the model. A linear relationship was obtained correlating the actual drug entrapped and the predicted values obtained from the NIR partial least squares regression model. The un-crosslinked tablet demonstrated a substantial weight gain (317% after 2h) and completely disintegrated after 3-4h whereas both 10 and 40% w/w genipin-crosslinked tablets showed lower weight gain (114 and 42% after 2h, respectively). A rapid floating of the tablets within 5-15min (compared to 45min for the marketed tablet) was observed, with maintained floating for 24h. Marketed and prepared tablets succeeded to prolong ALF release for 24h. The development of drug-loaded CAS nanoparticles using spray-drying represents a new alternative for the preparation of swellable floating tablets for prolonged drug release.