HPMC- A Marvel Polymer for Pharmaceutical Industry-Patent review

: At the present time, designing of defined release dosage forms, either controlled, sustained, modified, are gaining much importance. For the development of such delivery systems, proper blend of polymers is required, so that drug release occurs by polymer erosion, swelling, diffusion/dissolution. HPMC (hydroxypropyl methyl cellulose) is the most commonly used cellulosic polymer available in various grades to develop such types of systems. Depending upon the molecular weight and viscosity chosen, it can be applied for emulsification, adhesion, bonding, thickening, suspension, film forming and gelation. It consists of polymeric units linked together, which retain water, thereby acting as an excellent hydrophilic gel-forming polymer. It generally hydrates on the outer surface to form a gelatinous layer. It swells, expands upon contact with water and releases the drug in a predetermined manner initially and then forms a viscous gel to control the release further. The objective of the present review is to overview the recent patents and articles of HPMC, its properties, grades and its use in various drug delivery systems and as a binder, dispersing agent, bioavailability enhancer and as capsule forming material have been identified and reviewed.

Systematic Studies on Surface Erosion of Photocrosslinked Polyanhydride Tablets and Data Correlation with Release Kinetic Models

Photocrosslinkable polyanhydrides that undergo surface erosion are suitable materials for controlled-release drug delivery systems. Investigating the impact of different parameters on their erosion behavior is essential before use in drug delivery systems. Although their synthesis is well-established, parameters that may substantially affect the erosion of thiol-ene polyanhydrides including temperature and pH of the media, the geometry of the polymers, and the media shaking rate (the convective force for the polymer erosion), have not yet been studied. This study explores the effects of different environmental and geometric parameters on mass loss (erosion) profiles of polyanhydrides synthesized by thiol-ene photopolymerization. A comparative study on several release kinetic models fitting is also described for a better understanding of the polymer erosion behavior. The results demonstrated that although the temperature was the only parameter that affected the induction period substantially, the mass-loss rate was influenced by the polymer composition, tablet geometry, temperature, pH, and mass transfer (shaking) rate. With regard to geometrical parameters, polymers with the same surface area to volume ratios showed similar mass loss trends despite their various volumes and surface areas. The mass loss of polyanhydride tablets with more complicated geometries than a simple slab was shown to be non-linear, and the kinetic model study indicated the dominant surface erosion mechanism. The results of this study allow for designing and manufacturing efficient delivery systems with a high-predictable drug release required in precision medicine using surface-erodible polyanhydrides.

Understanding drug release from PCL/gelatin electrospun blends

Electrospinning is one of the efficient processes to fabricate polymeric fibrous scaffolds for several biomedical applications. Several studies have published to demonstrate drug release from electrospun scaffolds. Blends of natural and synthetic electrospun fibers provide excellent platform to combine mechanical and bioactive properties. Drug release from polymer blends is a complex process. Drug release from polymer can be dominated by one or more of following mechanisms: polymer erosion, relaxation, and degradation. In this study, electrospun polycaprolactone (PCL)–gelatin blends are investigated to understand release mechanism of Rhodamine B dye. Also, this article summarizes the effect of high-pressure carbon dioxide on drug loading and release from PCL–gelatin fibers. Results indicate that release media diffusion is a dominant mechanism for PCL–gelatin electrospun fibers. Thickness of electrospun mat becomes critical for blends with gelatin. As gelatin is highly soluble in water and has tendency of gelation, it affects diffusion of release media in and out of scaffold. This article is a key step forward in understanding release from electrospun blends.

Polyanhydrides: Synthesis, Properties, and Applications

This review focusses on polyanhydrides, a fascinating class of degradable polymers that have been used in and investigated for many bio-related applications because of their degradability and capacity to undergo surface erosion. This latter phenomenon is driven by hydrolysis of the anhydride moieties at the surface and high hydrophobicity of the polymer such that degradation and mass loss (erosion) occur before water can penetrate deep within the bulk of the polymer. As such, when surface-eroding polymers are used as therapeutic delivery vehicles, the rate of delivery is often controlled by the rate of polymer erosion, providing predictable and controlled release rates that are often zero-order. These desirable attributes are heavily influenced by polymer composition and morphology, and therefore also monomer structure and polymerization method. This review examines approaches for polyanhydride synthesis, discusses their general thermomechanical properties, surveys their hydrolysis and degradation processes along with their biocompatibility, and looks at recent developments and uses of polyanhydrides in drug delivery, stimuli-responsive materials, and novel nanotechnologies.

Characterization and Study on In Vitro Release of Praziquantel from Poly(lactide-co-glycolide) Implants

A series praziquantel-loaded poly(lactide-co-glycolide) implants are prepared by melt extrusion. The morphologies, structures and the in vitro releases are investigated. The results show that PZQ is dissolved or dispersed in the PLGA matrix and its crystal structure can be transformed into amorphous filament or flake-like structure. The in vitro release increased with the increase of the amount of low molecular weight PLGA0.13. The release of PZQ from the implant with a length of 20 mm is faster than that from that with a length of 10 mm. The macroscopic change and release curves of the implants reveal the drug release from the implants can be controlled by initial diffusion of drug from near the surface of implants followed by elution during polymer erosion.

Improving Drug Loading of Mucosal Solvent Cast Films Using a Combination of Hydrophilic Polymers with Amoxicillin and Paracetamol as Model Drugs

Solvent cast mucosal films with improved drug loading have been developed by combining carboxymethyl cellulose (CMC), sodium alginate (SA), and carrageenan (CAR) using paracetamol and amoxicillin as model drugs and glycerol (GLY) as plasticizer. Films were characterized using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), folding resilience, swelling capacity, mucoadhesivity, and drug dissolution studies. SA, CMC, and GLY (5 : 3 : 6) films showed maximum amoxicillin loading of 26.3% whilst CAR, CMC, and GLY (1 : 2 : 3) films had a maximum paracetamol loading of 40%. XRPD analysis showed different physical forms of the drugs depending on the amount loaded. Films containing 29.4% paracetamol and 26.3% amoxicillin showed molecular dispersion of the drugs while excess paracetamol was observed on the film surface when the maximum 40% was loaded. Work of adhesion was similar for blank films with slightly higher cohesiveness for CAR and CMC based films, but the differences were significant between paracetamol and amoxicillin containing films. The stickiness and cohesiveness for drug loaded films were generally similar with no significant differences. The maximum percentage cumulative drug release was 84.65% and 70.59% for paracetamol and amoxicillin, respectively, with anomalous case two transport mechanism involving both drug diffusion and polymer erosion.