Bashar Al-Taani

Effect of microenvironment pH of swellable and erodable buffered matrices on the release characteristics of diclofenac sodium

The aim of this work is to design pH-dependent swellable and erodable-buffered matrices and to study the effect of the microenvironment pH on the release pattern of diclofenac sodium. Buffered matrix tablets containing diclofenac sodium, physically mixed with hydrophilic polymer (hydroxypropyl methylcellulose [HPMC]) and pH-dependent solubility polymer (Eudragit L100-55) were prepared with different microenvironment pHs. The release of diclofenac sodium from the buffer matrices was studied in phosphate buffer solutions of pH 5.9 and 7.4. The swelling and erosion matrices containing only HPMC and Eudragit L100-55 were studied in phosphate buffer solution of pH similar to the microenvironment pHs of the matrices. Drug release from matrices was found to be linear as a function of time. Amount of drug released was found to be higher in the medium of pH 7.4 than that of pH 5.9. The rate of drug release increased with the increase of the microenvironment pH of the matrices as determined from the slope. The pattern of drug release did not change with the change of microenvironment pH. The swelling and erosion occurred simultaneously from matrices made up of HPMC and Eudragit L100-55. Both extent of swelling and erosion increased with increase of the medium pH. It was concluded from this study that changing the pH within the matrix influenced the rate of release of the drug without affecting the release pattern.

Preparation and characterization of microemulsion formulations of nicotinic acid and its prodrugs for transdermal delivery

At pharmacological doses, nicotinic acid has a lipid-regulating effect and is in use clinically for that purpose. However, despite of all features, its utility is strongly limited by several disadvantages such as, extensive hepatic metabolism and flushing. Transdermal delivery of nicotinic acid may, therefore, be the solution to reducing side effects associated with oral administration, and to maintaining constant therapeutic blood levels for longer duration. The aim of this investigation was to develop a suitable formulation or select a suitable vehicle for the transdermal delivery of highly lipophilic prodrugs of nicotinic acid (dodecyl and myristyl nicotinate) designed to deliver nicotinic acid through skin without causing vasodilatation and flushing and optimizing its delivery to the blood stream. A microemulsion system and penetration enhancers have been attempted in this study. The microemulsion system was composed of isopropyl myristate (IPM), water and a 4:1 (w/w) mixture of Labrasol and Peceol where a pseudoternary phase diagram was constructed. Furthermore, the microemulsion formulations with different component ratios were characterized by determination of conductivity, pH, particle size, viscosity and refractive index. According to the particle size analysis, conductivity and viscosity measurements, the microemulsion formulations that formed were of oil-in-water type. The transdermal permeability of nicotinic acid and its prodrugs was evaluated in vitro using Franz diffusion cells fitted with mice skin and nicotinic acid concentration was analyzed by high performance liquid chromatography. A theoretical design of percutaneous penetration optimization in which prodrugs derivation and enhancer application are combined based on the skin diffusion model was experimentally verified. The selected formulations seemed promising for developing a transdermal drug delivery system of nicotinic acid from dodecyl nicotinate that would offer advantages like possible controlled drug release, reduced flushing, increased drug stability and ease of large-scale production.

Release behaviour of diclofenac sodium dispersed in Gelucire® and encapsulated with alginate beads

Sustained release polymeric particles containing diclofenac sodium dispersed in Gelucire® matrix and encapsulated in calcium alginate shell were prepared with different drug-to-polymer ratios and also with different concentrations of sodium alginate for a fixed drug-to-polymer ratio in an aqueous environment. Spherical particles were formed by dropping an emulsion of diclofenac sodium in Gelucire® matrix, emulsified with sodium alginate, into calcium chloride solution. The gelled beads formed by ionotropic gelation of alginate with calcium ions showed sustained release of the water soluble drug in in-vitro release study. Drug release was a function of square-root of time, suggesting a matrix diffusion release pattern. The rate of release was significantly suppressed with increasing proportions of Gelucire® in the mixture. Sustained and complete release was achieved with Gelucire® of low melting point and low HLB value. No significant drug release occurred in a dissolution medium of pH 1.5, whereas complete release was observed at pH 6.8, consistent with considerable swelling of the alginate gel at this pH.

Low Molecular Weight Chitosan-Coated PLGA Nanoparticles for Pulmonary Delivery of Tobramycin for Cystic Fibrosis

(1) Background: Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with Tobramycin were prepared using a solvent-evaporation method. (2) Methods: The NPs were coated with low molecular weight chitosan (LMWC) to enhance the mucoadhesiveness of PLGA-NPs. The following w/w ratios of tobramycin to LMWC were prepared: control (0:0.50), F0 (1:0.25), F0.5 (1:0.5), and F1 (1:1). (3) Results: The results showed that the size of the particles increased from 220.7 nm to 575.77 nm as the concentration of LMWC used in the formulation increased. The surface charge was also affected by the amount of LMWC, where uncoated-PLGA nanoparticles had negative charges (−2.8 mV), while coated-PLGA NPs had positive charges (+33.47 to +50.13 mV). SEM confirmed the size and the spherical homogeneous morphology of the NPs. Coating the NPs with LMWC enhanced the mucoadhesive properties of the NPs and sustained the tobramycin release over two days. Finally, all NPs had antimicrobial activity that increased as the amount of LMWC increased. (4) Conclusion: In conclusion, the formulation of mucoadhesive, controlled-release, tobramycin-LMWC-PLGA nanoparticles for the treatment of P. aeruginosa in cystic fibrosis patients is possible, and their properties could be controlled by controlling the concentration of LMWC.

Effect of different polymeric dispersions on In-vitro dissolution rate and stability of celecoxib class II drug

Solid dispersions can play a significant role in the enhancement of drug dissolution and stability. Still, the polymeric effect can vary according to the possibility of intermolecular forces with the drug. The objective of this study was to evaluate the effect of several polymers on enhancement in-vitro dissolution behavior of celecoxib; in addition to comparing prepared dispersions with selected commercial products. Solid dispersions of celecoxib were prepared with different ratios between the drug and selected polymer (Soluplus®, polyvinyl pyrrolidine, Chitosan, polyethylene glycol). Physicochemical characterizations were performed using Powder X-ray diffraction, Differential Scanning Calorimetry, Fourier Transform Infra-Red analysis and Scanning Electron Microscopy. Dispersions were subjected to in-vitro drug release studies. Results revealed enhancement in dissolution rate for all dispersions prepared except for Chitosan-based dispersions that showed clear retardation in the drug release. Prepared dispersions from other polymers succeeded to match with release profile of two commercially marketed products (Celebrex® and Flamex®). Further Characterization of Chitosan dispersions revealed presence celecoxib in its crystalline form entrapped inside Chitosan carrier with the presence of two hydrogen bonding between Chitosan and celecoxib. Although both Polyvinylpyrrolidone, and polyethylene glycol dispersions showed a great enhancement in drug release; both failed to maintain stability. Sticky paste formation occurred to dispersions, and recrystallization took place in polyethylene glycol dispersions.

Delivery of Peptidic Gonadotropin Releasing Hormone Antagonists

GnRH antagonists have several clinical applications in prostate cancer, regulation of ovulation induction in females, breast cancer, male contraception and others. Antagonists differ from natural GnRH decapeptide in having five or more amino acid substitutions, whereas most of the antagonists are available as subcutaneous (SC) formula for injection some are formulated as a depot formulation for sustained release (e.g., Cetrorelix, Degarelix). Systemic delivery of cetrorelix acetate by intratracheal route can be achieved using dry powder for inhalation of the adhesive mixture when the powder deposition reaches stage four. The oral route for systemic delivery of peptide without its degradation can be achieved using gastrointestinal permeation enhancement technology GIPET® provided by acyline.