Wassim Abdelwahed - Academia.edu (original) (raw)

Papers by Wassim Abdelwahed

Vitamin E or ␣-tocopherol is widely used as a strong antioxidant in many medical and cosmetic app... more Vitamin E or ␣-tocopherol is widely used as a strong antioxidant in many medical and cosmetic applications, but is rapidly degraded, because of its light, heat and oxygen sensitivity. In this study, we applied the nanoprecipitation method to prepare vitamin E-loaded nanocapsules, at laboratory-scale and pilotscale. We scaled-up the preparation of nanocapsule with the membrane contactor technique. The effect of several formulation variables on the vitamin E-loaded nanocapsules properties (mean diameter, zeta potential, and drug entrapment efficiency) was investigated. The optimized formulation at laboratoryscale and pilot-scale lead to the preparation of vitamin E-loaded nanocapsules with mean diameter of 165 and 172 nm, respectively, and a high encapsulation efficiency (98% and 97%, respectively).

International Journal of Pharmaceutical Sciences and Nanotechnology, 1970

This study was designed to find the best method to separate proanthocyanidins from other phenolic... more This study was designed to find the best method to separate proanthocyanidins from other phenolic compounds extracted from pomegranate’s peel and to investigate their radical scavenging capacity. Water is used as an effective solvent for extracting antioxidant compounds from pomegranate’s peel (Punica granatum). The final extract contained closely related compounds not readily separable. Proanthocyanidins are the most potent antioxidant found in this extract and the purification and separation from other phenolic compounds is an important challenge. A comparison of two SPE cartridges, including silica-based C18 and aminopropyl for the isolation and purification of proanthocyanidins extracted from pomegranate’s peel, showed that the proposed SPE method with aminopropyl cartridge using alkalized aqueous acetone as eluent was more effective for the purification and the separation of extractable proanthocyanidins.

International journal of pharmaceutics, Jan 3, 2008

The aim of this work was to study the preparation of nanospheres from amphiphilic beta-cyclodextr... more The aim of this work was to study the preparation of nanospheres from amphiphilic beta-cyclodextrins formed (a) by different acylation degrees (DA) at the secondary hydroxyl face (DA=14 and 21) followed by varying (b) the sulfatation degrees (DS) at the primary hydroxyl face (DS=0, 4 and 7). The physicochemical properties of the synthesized compounds such as molecular weights, the theoretical HLB values and the critical micellar concentration values and their surface area were presented. The nanoparticles prepared from amphiphilic beta-cyclodextrins were characterized by mean size, zeta potential and their morphology. The compounds presented hydrophile-lipophile balance values ranging from 5.6 to 10. For sulfated amphiphilic beta-cyclodextrins having HLB values higher than 8, were able to self-organize in water to form nanoparticles. However, for the amphiphilic beta-cyclodextrins that HLB values lower than 6.6 are insoluble in water but soluble in organic solvents rendering possibl...

International Journal of Pharmaceutics, 2012

International Journal of Pharmaceutics, 2006

The freeze-drying kinetics and the superficial porosity development of grapefruit puree. The impa... more The freeze-drying kinetics and the superficial porosity development of grapefruit puree. The impact of biopolymers addition (gum Arabic and bamboo fiber) and to apply (40 ºC) or not shelf temperature (room temperature) was considered. To increase the shelves temperature during freeze-drying allowed to an important drying time reduction and doesn't supposed a lower porosity related to the collapse development of the structure. Biopolymers do not affect the drying kinetics. From this results, biopolymers addition and to heat at least up to 40 ºC during grapefruit freeze-drying should be recommended.

ijppsjournal.com

Research Article PREPARATION AND CHARACTERIZATION OF NEW ORAL LYOPHILIZATES CONTAINING A NON STER... more Research Article PREPARATION AND CHARACTERIZATION OF NEW ORAL LYOPHILIZATES CONTAINING A NON STEROIDAL ANTI INFLAMMATORY DRUG ROULA SAFARab, WASSIM ABDELWAHEDa, MUSTAFA F. CHEHNAa*,GHANIA DEGOBERTb, HATEM FESSIb ...

European Journal of Pharmaceutics and Biopharmaceutics, 2003

Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been applied to the ima... more Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been applied to the imagery of solid lipid nanoparticles (SLNs) formulated from an amphiphilic cyclodextrin, 2,3-di-o-alkanoyl-b-cyclodextrin, b-CD21C6. Comparison of the results shows that the vacuum drying technique used in sample preparation for SEM causes shrinkage in the size of the SLNs, whereas the deposition method used for AFM causes the SLNs to form small clusters. The hydrodynamic diameter determined from photon correlation spectroscopy (PCS) is 359^15 nm and the zeta potential is 225 mV.

European Journal of Pharmaceutics and Biopharmaceutics, 2006

Freeze-drying was recently applied to improve the long-term storage stability of nanoparticles. N... more Freeze-drying was recently applied to improve the long-term storage stability of nanoparticles. Nanocapsules have a thin polymeric envelope that may not withstand the stresses of such process. So, cryoprotectants and lyoprotectants are usually added to the formulation to protect these vectors during freezing and desiccation steps. The aim of this paper was to investigate the importance of the vitrification of cryoprotectants on the stabilization of nanocapsules during freezing, desiccation, and storage steps. Furthermore, the effect of stabilizer crystallization on the conservation of nanocapsules properties was studied. Finally, the effect of temperature storage and relative humidity on the stability of nanocapsules was tested through an accelerated stability study. Results indicate that nanocapsules stabilization during the different steps of freeze-drying requires their dispersion within a vitrified matrix of amorphous excipient to protect them against the stress of freezing and dehydration. The crystallization of this stabilizer during the freezing, the desiccation or the storage steps can destabilize these fragile particles. Electron spectroscopy for chemical analysis revealed the adsorption of nanocapsules at the interface ice/liquid during the freezing step. Such adsorption must be avoided in the case of freeze-drying of immuno-nanoparticles to preserve the native structure of proteins attached to their surface.

Advanced Drug Delivery Reviews, 2006

Freeze-drying has been considered as a good technique to improve the long-term stability of collo... more Freeze-drying has been considered as a good technique to improve the long-term stability of colloidal nanoparticles. The poor stability in an aqueous medium of these systems forms a real barrier against the clinical use of nanoparticles. This article reviews the state of the art of freeze-drying nanoparticles. It discusses the most important parameters that influence the success of freeze-drying of these fragile systems, and provides an overview of nanoparticles freeze-drying process and formulation strategies with a focus on the impact of formulation and process on particle stability.

Poor ocular bioavailability of drugs (<1%) from conventional eye drops (i.e., solution, suspen... more Poor ocular bioavailability of drugs (<1%) from conventional eye drops (i.e., solution, suspension, and ointments) is mainly due to the physiologic barriers of the eye. In general, ocular efficacy is closely related to ocular drug bioavailability, which may be enhanced by increasing corneal drug penetration and prolonging precorneal drug residence time. In our current work, we developed a colloidal system that is polycaprolactone (PCL) nanoparticles for Gatifloxacin ophthalmic delivery, to improve precorneal residence time and ocular penetration for enhanced drug bioavailability. In this research, we studied nanoparticles preparation procedures and the effect of process variables on its characters. Nanoparticles were prepared by nanoprecipitation technique and characterized for various properties such as particle size, polydispersity index PdI, zeta potential and Entrapment efficiency EE%. The developed nanosuspension showed a mean particle size in the range of 184 to 207nm, suit...

SSRN Electronic Journal, 2021

Aims: The green synthesis of silver nanoparticles in an eco-friendly, economical and more effecti... more Aims: The green synthesis of silver nanoparticles in an eco-friendly, economical and more effective approach using Acacia cyanophylla plant extract and study the effect of preparing conditions on the size of synthesis nanoparticles and its antibacterial activity. Methodology: In this study, we synthesis of silver nanoparticles by reduction method using aqueous silver nitrate solution and aqueous extract of Acacia cyanophylla. Then, studying their characterization by several methods, such as visual inspection, UV–Vis spectroscopy, and dynamic light scattering and scanning electron microscope and then study the effect of silver nitrate: extract ratio, type extract, temperature, reaction time on the size of prepared nanoparticles and also the antibacterial effect of these nanoparticles was studied on Escherichia coli using micro-dilution method and determination the Minimum Inhibitory Concentration (MIC). Results: The results showed that the silver nanoparticles prepared using Acacia c...

Objective: The aim of this work is to investigate formulation and process parameters that could i... more Objective: The aim of this work is to investigate formulation and process parameters that could impact freeze drying of loperamide-loaded Solid Lipid Nanoparticles (Loperamide loaded SLN). Methods: Loperamide loaded SLN was prepared by high shear homogenization method and freeze dried in vials without and with different types and concentrations of cryoprotectants (lactose, glucose, mannitol and povidon) using pilot freeze dryer. Results: The best result has been obtained by using 5 % of monosaccharide glucose solution, although Nanoparticles size has been increased 6 folds. However, the total concentration of loperamide hydrochloride (Loperamide HCl) remained unchanged after freeze drying. It has been found that the type and ratio of surfactants adsorbed at the surface of SLN have impact on the success of the drying process. Conclusion: Results revealed that polymeric nanoparticles could withstand freeze drying stress more than SLN because polymers have higher mechanical resistance ...

Objective: Aim of present study was to provide stable formulation of enalapril maleate 20 mg that... more Objective: Aim of present study was to provide stable formulation of enalapril maleate 20 mg that can be manufactured simply, in a time efficient by using direct compression and on a large industrial scale. Methods: Four Enalapril maleate formulations were prepared using three different lubricants consisting of Glyceryl monostearate, sodium stearyl fumarate and zinc stearate and the same stabilizer citric acid anhydrous. Tablets were prepared by employing direct compression technique and evaluated for post compression parameters such as determination of appearance, disintegration time, friability, dissolution, assay and related substances as well as stability and industrial difficulties during manufacturing like sticking. The tablets were packed in blister Aluminum/Aluminum. The four formulations were subjected to stability studies as per ICH guidelines at temperatures and humidity of 40 C / 75% RH for six months. Formulation III and IV were kept for 12 months at the same conditions...

Objective: The aim of this study was to prepare stable all-trans retinoic acid or tretinoin (RA) ... more Objective: The aim of this study was to prepare stable all-trans retinoic acid or tretinoin (RA) loaded liposome formulation with high encapsulation efficiency intended for immediate application on the skin using the simple preparation method. Methods: Formulas were prepared by heating method. The effect of formulation variables on liposome properties was investigated. Dynamic Light Scattering Process (DLS) and the electrophoretic mobility process were used to determine the mean size and zeta potential, respectively. The encapsulation efficiency % was determined spectrophotometrically. Six liposome formulas (Fs) were prepared. Three types of phospholipids and two ratios of cholesterol were used. Sodium cholesteryl sulfate (SCS) was added to all formulas except formula 1. Six formulas and topical ethanolic solution of RA was stored at accelerated storage conditions for six months. EE% was determined by validated H. P. L. C method in the stage of the stability study. Results: pH=6.5 s...

L'objectif de ce travail a ete d'etudier les differents aspects de la formulation et du p... more L'objectif de ce travail a ete d'etudier les differents aspects de la formulation et du procede de lyophilisation de vecteurs colloidaux de type nanocapsules, nanospheres et nanoemuslions. Cette methode industrielle de sechage ameliore la stabilite a long-terme des vecteurs colloidaux. Dans une premiere approche, nous avons etudie les differents parametres de la formulation des nanocapsules preparees par la methode d'emulsification-diffusion de solvant et stabilisees par la poly (alcool de vinyle) (PVA). Il a ete trouve que la concentration de PVA et l'ajout d'un cryoprotecteur sont les parametres les plus importants pour la reussite de la lyophilisation de nanocapsules. La seconde approche a consiste a etudier le mecanisme de stabilisation des nanocpasules par les differents type d'excipients pendant les differentes etapes de la lyophilisation et pendant le stockage. D'apres les resultats, la vitrification des cryoprotecteurs et lyoprotecteurs semble etr...

International Journal of Pharmaceutical Sciences and Nanotechnology, 2012

Bulletin of Pharmaceutical Sciences. Assiut

Research Journal of Pharmacy and Technology