Structure-based design and evaluation of synthetic porphyrin derivatives as G-quadruplex stabilizing anticancer agents

G-quadruplex structures formed in telomeres and proto-oncogene represent a potentially useful target for anticancer drugs. Stabilization of this arrangement may inhibit the further action of different enzymes involved in cancer cell immortalization. In present work structure based drug design and synthesis was carried out on series of meso-substituted porphyrin analogues. The interaction of porphyrin derivatives with G-quadruplex DNA has been explored by virtual screening procedure. Some of the potential binding agents were then synthesized and evaluated in-vitro by MTT and PCR stop assay. The study indicates that these compounds had strong G-Quadruplex binding affinity with very good inhibitory activity in MCF-7 and A549 cell lines.

Formulation and optimization of mucoadhesive buccal patches of losartan potassium by using response surface methodology

BACKGROUND

This study was undertaken with an aim to systematically design a model of factors that would yield an optimized sustained release dosage form of an anti-hypertensive agent, losartan potassium, using response surface methodology (RSM) by employing 3(2) full factorial design.

MATERIALS AND METHODS

Mucoadhesive buccal patches were prepared using different grades of hydroxypropyl methylcellulose (HPMC) (K4M and K100M) and polyvinylpyrrolidone-K30 by solvent casting method. The amount of the release retardant polymers - HPMC K4M (X1) and HPMC K100M (X2) was taken as an independent variable. The dependent variables were the burst release in 30 min (Y1), cumulative percentage release of drug after 8 h (Y2) and swelling index (Y3) of the patches. In vitro release and swelling studies were carried out and the data were fitted to kinetic equations.

RESULTS

The physicochemical, bioadhesive, and swelling properties of patches were found to vary significantly depending on the viscosity of the polymers and their combination. Patches showed an initial burst release preceding a more gradual sustained release phase following a nonfickian diffusion process.

DISCUSSION

The results indicate that suitable bioadhesive buccal patches with desired permeability could be prepared, facilitated with the RSM.

Azithromycin novel drug delivery system for ocular application

Background:

Azithromycin (AZT) is a macrolide antibiotic derived from and similar in structure to erythromycin. Oral administration of AZT is effective for the treatment of trachoma; however, topical formulations are difficult to develop because of the drug's hydrophobicity. The aim of this study is to formulate a novel topical ophthalmic delivery system of AZT.

Materials and Methods:

In the present study, ocular inserts of AZT are prepared using alginate, carbopol, and hydroxypropyl methylcellulose (HPMC) to solve the said formulation problem of drug and to facilitate ocular bioavailability. Ocular inserts were prepared by film casting method and the prepared films were subjected to investigations for their physical and mechanical properties, swelling behaviors, ex vivo bioadhesion, and in vitro drug release. Ocular irritation of the developed formulation was also checked by hen's egg chorioallantoic membrane test for ocular irritation potential.

Results:

The physicochemical, bioadhesive, and swelling properties of films were found to vary significantly depending on the type of polymers used and their combinations. The alginate films exhibited greater bioadhesion and showed higher tensile strength and elasticity than the carbopol films. HPMC addition to the films significantly affected the properties of ocular inserts. Carbopol:HPMC (30:70)-based ocular inserts sustained drug release for longest span of 6 h. The release profile of AZT showed that drug release was by both diffusion and swelling. The formulation was found to be practically nonirritant in ocular irritation studies.

Conclusion:

AZT can therefore be developed as an ocular insert delivery system for the treatment of ocular surface infections.

Piroxicam bioadhesive ocular inserts: physicochemical characterization and evaluation in prostaglandin-induced inflammation

PURPOSE

An attempt has been made in the present research to formulate piroxicam into bioadhesive ocular inserts with an objective to sustain drug release, reduce frequency of dosing, and enhance ocular bioavailability of piroxicam.

MATERIAL AND METHODS

Drug matrices were prepared using film forming polymer, PVP and bioadhesive polymers, HPMC, CMC, and carbopol. Ocular inserts were prepared by film casting method and prepared films were subjected to investigations for their physical and mechanical properties, swelling behaviors, ex vivo bioadhesion, and in vitro drug release. The optimized formulation was tested and compared with eye drops of piroxicam for ocular anti-inflammatory activity in rabbits against PGE(2)-induced inflammation.

RESULTS

The physicochemical, bioadhesive, and swelling properties of films were found to vary significantly depending on the type of the polymers and their combination. The above properties were found to be optimum for all films; however, formulation containing carbopol 0.5% and HPMC 1% was found to be the best film as it shows good adhesion, acceptable pH, and gives a reasonable drug release (99% at 12 hr). Kinetic studies indicated both diffusion and swelling as mechanism of drug release from this matrix. Further in vivo studies with this formulation indicated a significant inhibition of PGE(2)-induced lid closure and PMN migration as compared to eye drops formulation.

CONCLUSION

Formulation was found promising, as it sustained the drug release and enhanced the ocular bioavailability of piroxicam as compared to piroxicam eye drops.

Alginate-chitosan film for ocular drug delivery: effect of surface cross-linking on film properties and characterization

The characteristics of alginate-chitosan films intended for ocular drug delivery of gatifloxacin sesquihydrate were compared with the ionically surface cross-linked films of similar compositions. The effect of polymer ratios and cross-linking was studied relatively to various parameters of formulations including physicochemical, mechanical strength, swelling and bioadhesion. The drug release profiles and drug release mechanisms were compared. The folding endurance, tensile strength, bioadhesive strength considerably increased whereas swelling index, elongation at break decreased with surface cross-linking of the films. Surface cross-linked formulation F3 (2% w/v sodium alginate and 1% w/v chitosan) showed most prolonged drug release of 24 h indicating the potential of surface cross linking of the film to sustain drug release. As per the kinetic models both type of films showed a constant drug release, however the drug release mechanism transformed from erosion to diffusion after cross linking. These results demonstrate that the surface treated alginate-chitosan film could be a potential vehicle to enhance ocular GS bioavailability and patient compliance.