The release dynamics of model drugs from the psyllium and N-hydroxymethylacrylamide based hydrogels

Synthesis and characterization of modified bioactive arabinoxylan-psyllium: Evaluation of molecular interactions, physiochemical and biomedical properties

Keeping in view the future prospectus of carbohydrate polymers, present research report is an elaboration, exploration and execution of the research expectancy in area of these polymers by researchers like John F. Kennedy. Herein, molecular interactions and physiochemical properties of modified bioactive arabinoxylan-psyllium have been evaluated for drug delivery applications. Arabinoxylan-psyllium was modified with sulphated and amide copolymers and co-polymers were characterized by SEMs, AFM, FTIR, XRD, solid state ¹³C NMR, TGA-DSC and water absorption studies. The ¹³C-NMR and FTIR confirmed grafted copolymers. The polymer-blood interactions revealed non-thrombogenic nature with thrombose percentage 63.17 ± 5.61 % and polymer-mucous membrane interactions showed detachment force 0.237 ± 0.078Nwith bio-membrane in mucoadhesion test. The pH responsible gels exhibited 44.49 ± 3.12 % inhibitions of free radicals in DPPH assay. The polymer-drug interactions demonstrated sustained diffusion of methotrexate with non-Fickian diffusion and Korsmeyer-Peppas kinetic model. Overall, co-polymeric network structure was found useful in colon specific drug delivery.

Hydration Patterns in Sodium Alginate Polymeric Matrix Tablets-The Result of Drug Substance Incorporation

The purpose was to show, using destructive/nondestructive methods, that the interplay between water, tablet structure, and composition determine the unique spatiotemporal hydration pattern of polymer-based matrices. The tablets containing a 1:1 w/w mixture of sodium alginate with salicylic acid (ALG/SA) or sodium salicylate (ALG/SNA) were studied using Karl Fischer titration, differential scanning calorimetry, X-ray microtomography, and magnetic resonance imaging. As the principal results, matrix specific features were detected, e.g., "locking" of the internal part of the matrix (ALG/SA); existence of lamellar region associated with detection of free/freezing water (ALG/SA); existence of water penetrating the matrix forming specific region preceding infiltration layer (ALG/SNA); switch in the onset temperature of endothermic water peak associated with an increase in the fraction of non-freezing water weight per dry matrix weight in the infiltration layer (ALG/SNA). The existence of complicated spatiotemporal hydration patterns influenced by matrix composition and molecular properties of constituents has been demonstrated.

Optimized copolymeric microstructured platforms for smart controlled delivery of an anticoagulant drug: Preparation, in vitro assessment and crossover study in healthy adult human volunteers

In the present study, novel micro-structured copolymeric carriers were developed based on the grafting technology where acrylamide was chemically crosslinked with different types of Eudragits® (NE30D, L100, RL30D, or RS30D) based on a 4¹*2¹ factorial design. The designed systems efficiently engulfed the anticoagulant drug dipyridamole (DIP), within their formed entangled mesh of crosslinked polymeric network. An optimized formulation, ECOP4 with a desirability-value of 0.706, (in which DIP is engulfed within a copolymeric network of acrylamide and Eudragit® RS30D) showed high engulfment capacity (97.13 ± 1.34%) and controlled DIP release over 8 h. FTIR studies revealed absence of interactions between DIP and the formed copolymer. ECOP4 was further inserted within an easily-administered safe raft forming system composed of a mixture of LM-pectin and gellan gum. A pharmacokinetic study was performed using human volunteers to determine DIP concentration in their plasma after administering the designed formulation using the high-performance liquid chromatography (HPLC) method. A crossover design was adopted comparing the designed formulation with Persantin® 25 mg tablets as a reference standard. Superior results were obtained for the optimized formulation regarding the measured pharmacokinetic parameters (AUC_0-24h, C_max, and T_max) with a 2.31 fold increase in relative bioavailability, which reveals the usefulness of the designed grafted dipyridamole formulation in site-specific delivery system.

An immobilized invertase enzyme for the selective determination of sucrose in fruit juices

Poly(N-vinylpyrrolidone-co-butylacrylate-co-N-hydroxymethylacrylamide) has been synthesized by free radical polymerization at 70 °C. Copolymer were characterized by FT-IR, elemental analysis and viscometric methods. Invertase was immobilized onto poly(N-vinyl pyrrolidone-co-butyl acrylate-co-N-hydroxymethyl acrylamide) by entrapment method. Optimum parameters (pH, temperature, substrate concentration, amount of polymer) for immobilization to obtain maximum activity were investigated. Kinetic parameters, K_m and V_max, of the free and immobilized invertases were also assayed. Results showed that immobilization enhanced the enzyme stability against changes of pH and temperature and immobilized enzyme showed lower K_m value than free enzyme. One of the most interesting results is that the optimum operational temperature of the immobilized enzyme was 15 °C higher than that of the free enzyme. The next is the activity of the immobilized enzyme at the optimum temperature (70 °C) was approximately the same as the activity of the free enzyme at its optimum temperature (55 °C). Finally, immobilized invertase were used for determination of sucrose in commercial fruit juices. A new method and equation based on immobilized invertase were derived for determination of sucrose in commercial cheryy and pomegranate juices.

Lornoxicam controlled release transdermal gel patch: Design, characterization and optimization using co-solvents as penetration enhancers

The aim of the current study was to develop membrane-based transdermal patches of lornoxicam gel using oleic acid (OA)and propylene glycol (PG) as penetration enhancers to improve drug delivery across the skin and to evaluate in vivo analgesic and anti-inflammatory activity. For this purpose, nine formulations were developed in accordance with 32 factorial design using Design Expert® 11. The concentration of propylene glycol (X1) and oleic acid (X2) were selected as independent variable whereas Q10 (Y1), flux (Y2) and lag time (Y3) were considered as the response variables. The impact of drug loading, surface area, gel concentration, membrane variation and agitation speed on drug release and permeation was also studied. The skin sensitivity reaction, analgesic activity and anti-inflammatory action of the optimized patch were also determined in Albino Wistar rats. Stability studies were performed for three months at three different temperature conditions. The result suggests that a membrane-based system with controlled zero-order drug release of 95.8 ± 1.121% for 10 h exhibiting flux of 126.51±1.19 μg/cm2/h and lag time of 0.908 ±0.57h was optimized with the desired analgesic and anti-inflammatory effect can be obtained by using propylene glycol and oleic acid co-solvents as a penetration enhancer. The patch was also found stable at 4˚C for a period of 6.44 months. Formulation F9 comprising of 10% PG and 3% OA was selected as an optimized formulation. The study demonstrates that the fabricated transdermal system of lornoxicam can deliver the drug through the skin in a controlled manner with desired analgesic and anti-inflammatory activity and can be considered as a suitable alternative of the oral route.

Swelling behavior of poly (N-hydroxymethylacrylamide-co-acrylic acid) hydrogels and release of potassium nitrate as fertilizer

Poly (N-hydroxymethylacrylamide-co-acrylic acid) [P(NHMA-AAx)] hydrogels were prepared by free-radical polymerization in aqueous solution at 56°C, using N,N′-methylenebisacrylamide as the cross-linking agent. The synthesized hydrogels were subsequently investigated by a series of characterization techniques including Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis and differential scanning calorimetry analysis. The effects of comonomer composition in the feed, pH, temperature and ionic strength on the swelling behavior were studied. Results indicated that the swelling capabilities of P(NHMA-AAx) hydrogels decreased with the increase in N-hydroxymethylacrylamide (NHMA) content in the polymeric matrix and ionic strength of the medium. Additionally, the hydrogels showed both temperature and pH responses. The dynamic swelling behaviors of hydrogels at different pH values followed a non-Fickian type. The P(NHMA-AAx) hydrogels were also loaded with potassium nitrate (KNO3) as a model agrochemical, and the release kinetics of fertilizer from the hydrogels was studied as a function of KNO3 and NHMA concentrations. Moreover, various kinetic parameters, such as release exponents and diffusion coefficients, were calculated.

Ex-vivoand in-vitro assessment of mucoadhesive patches containing the gel-forming polysaccharide psyllium for buccal delivery of chlorhexidine base

The aim of the present study was to evaluate the gel-forming polysaccharide psyllium in the preparation of mucoadhesive patches for the controlled release of chlorhexidine (CHX) to treat pathologies in the oral cavity, using the casting-solvent evaporation technique. A number of different film-forming semi-synthetic polymers, such as sodium carboxymethyl cellulose (SCMC) and hydroxypropylmethyl cellulose (HPMC) were evaluated for comparison. The patch formulations were characterized in terms of drug content, morphology surface, swelling and mucoadhesive properties, microbiology inhibition assay and in vitro release tests. Three ex-vivo testswere carried out using porcine mucosa: an alternative dissolution test using artificial saliva that allows contemporary measurement of dissolution and mucoadhesion, a permeation test through the mucosa and the measurement of mucoadhesion using a Nouy tensile tester, as the maximum force required for the separation of the patch from the mucosa surface. The patches were also examined for determination of the minimum inhibitory concentration in cultures of Escherichia coli and Staphylococcus aureus. All the patches incorporating psyllium were found suitable in terms of external morphology, mucoadhesion and controlled release of the drug: in the presence of psyllium the drug displays prolonged zero-order release related to slower swelling rate of the system.

"Development and evaluation of sodium alginate-polyacrylamide graft-co-polymer-based stomach targeted hydrogels of famotidine"

In the present study, grafting technology has been used to develop novel grafted hydrogel beads as controlled drug delivery carriers. The chemical crosslinking and grafting of polyacrylamide onto sodium alginate has been found to be efficient method for the development of new polymeric carrier. The successful crosslinking has been confirmed by Fourier transformed infrared spectroscopy, thermogravimetric analysis, and elemental analysis. The polymeric network of sodium alginate-co-polyacrylamide (NaAlg-g-PAM) has been interlinked by covalent and hydrogen bonds which also strength the gel network. Simple ionotropic gelation method has been used for the preparation of NaAlg-g-PAM hydrogel beads. Its swelling and gelation were dependent on monomer and crosslinker concentrations. Entrapment of the drug moiety (famotidine; an antiulcer drug) within the grafted beads has been confirmed by X-ray powder diffraction and differential scanning calorimetry. More than 75% of drug loading in beads occurred with the increase of monomer and crosslinker concentration. In vitro drug release was found to be sustained up to the 12 h with 80% drug release.

Pharmaceutical applications of various natural gums, mucilages and their modified forms

A large number of plant based pharmaceutical excipients are available today. Gums and mucilages are the most commonly available plant ingredients with a wide range of applications in pharmaceutical and cosmetic industries. They are being used due to their abundance in nature, safety and economy. They have been extensively explored as pharmaceutical excipients. They are biocompatible, cheap and easily available. Natural materials have advantages over synthetic ones since they are chemically inert, nontoxic, less expensive, biodegradable and widely available. They can also be modified in different ways to obtain tailor-made materials for drug delivery systems and thus can compete with the available synthetic excipients. Recent trend toward the use of plant based and natural products demands the replacement of synthetic additives with natural ones. In this review, we describe the pharmaceutical applications of various natural gums, mucilages and their modified forms for the development of various drug delivery systems.

Preliminary evaluation of molecular imprinting of 5-fluorouracil within hydrogels for use as drug delivery systems

Molecular imprinting is a new and rapidly evolving technique used to create synthetic receptors and it possesses great potential in a number of applications in the life sciences. Keeping in mind the therapeutic importance of 5-fluorouracil (5-FU) and the technological significance of molecular imprinting polymers, the present study is an attempt to synthesize 2-hydroxyethylmetacrylate- and acrylic acid-based 5-FU imprinted hydrogels. For the synthesis of these hydrogels, N,N'-methylenebisacrylamide was used as a crosslinker, ammonium persulfate as an initiator and N,N,N',N'-tetramethylethylenediamine as an accelerator. Both molecular imprinted polymers (MIPs) and non-imprinted polymers were synthesized at the optimum crosslinker concentration obtained from swelling studies and used to study their recognition affinity, their swelling and the in vitro release dynamics of the drug. It was observed from this study that the recognition affinity of MIPs is increased when these are synthesized in a high concentration template solution.

In vitro release dynamics of thiram fungicide from starch and poly(methacrylic acid)-based hydrogels

In order to make the judicious use of pesticide/fungicide and to maintain the environment and ecosystem we have developed the starch and poly(methacrylic acid)-based agrochemical delivery system for their controlled and sustained release. The delivery device was prepared by using N,N'-methylenebisacrylamide (N,N'-MBAAm) as crosslinker and was characterized with FTIR, TGA and with swelling studies as a function of time and crosslinker concentration. This article discusses the swelling kinetics of polymer matrix and release dynamics of thiram (fungicide) from hydrogels for the evaluation of the diffusion mechanism and diffusion coefficients. The values of the diffusion exponent 'n' for both cases, that is the swelling of hydrogels and for the release of thiram from the hydrogels have been observed between 0.7 and 0.9 when the concentration of the crosslinker in the polymers were varied from 6.49x10(-3) to 32.43x10(-3) moles/L. It is inferred from the values of the 'n' that Non-Fickian diffusion mechanism has occurred in both the cases.

Controlled release of thiram fungicide from starch-based hydrogels

In order to make the judicious use of thiram fungicide and to exploit the potential of agri-polymers, we have developed the starch- poly(acrylamide) and starch-poly(acrylic acid) based agrichemical delivery system (hydrogels) for its controlled and sustained release. Polymeric networks have been prepared by using N,N'-methylenebisacrylamide (N,N-MBAAm) as crosslinker and ammonium persulfate (APS) as initiator and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and swelling studies. Release dynamics of thiram fungicide from polymeric matrices has been studied for the evaluation of the diffusion mechanism and diffusion coefficients. It has been established that Non-Fickian diffusion mechanism has occurred for the release of thiram from these polymeric matrices. Furthermore, the initial rate of diffusion of thiram from these polymeric matrices is more as compared to the late stages of diffusion, which is analogous to the trends obtained for the diffusion of water molecules from these polymer matrices.