In vitro drug release from porous cellulose matrices

Curcumin-loaded alginate hydrogels for cancer therapy and wound healing applications: A review

Hydrogels have emerged as a versatile platform for a numerous biomedical application due to their ability to absorb a huge quantity of biofluids. In order to design hydrogels, natural polymers are an attractive option owing to their biocompatibility and biodegradability. Due to abundance in occurrence, cost effectiveness, and facile crosslinking approaches, alginate has been extensively investigated to fabricate hydrogel matrix. Management of cancer and chronic wounds have always been a challenge for pharmaceutical and healthcare sector. In both cases, curcumin have been shown significant improvement and effectiveness. However, the innate restraints like poor bioavailability, hydrophobicity, and rapid systemic clearance associated with curcumin have restricted its clinical translations. The current review explores the cascade of research around curcumin encapsulated alginate hydrogel matrix for wound healing and cancer therapy. The focus of the review is to emphasize the mechanistic effects of curcumin with its fate inside the cells. Further, the review discusses different approaches to designed curcumin loaded alginate hydrogels along with the parameters that regulates their release behavior. Finally, the review is concluded with emphasize on some key aspect on increasing the efficacy of these hydrogels along with novel strategies to further develop curcumin loaded alginate hydrogel matrix with multifacet applications.

Tailored beads made of dissolved cellulose--investigation of their drug release properties

In the frame of this work, we have investigated drug entrapping and release abilities of new type of porous cellulose beads (CBs) as a spherical matrix system for drug delivery. For that purpose, CBs prepared with three different methods were used as drug carriers and three compounds, anhydrous theophylline (Thp), riboflavin 5'-phosphate sodium (RSP) and lidocaine hydrochloride monohydrate (LiHCl) were used as model drug substances. The loading procedure was carried out by immersing swollen empty beads into the solutions of different concentrations of model drugs. The morphology of empty and loaded beads was examined using a field emission scanning electron microscopy (FE-SEM). Near-infrared (NIR) imaging was performed to identify the drug distributions on and within the loaded CBs. The drug amount incorporated into CBs was examined spectrophotometrically and in vitro drug release studies were performed to determine the drug release rates. The results of FE-SEM and chemical NIR imaging analyses revealed that incorporated drug were distributed on the surface and but also within the internal structure of the CBs. Physical properties of CBs and solubility of model drugs had effect on loading efficacy. Also, the drug release rates were controlled by solubility of model drugs (diffusion controlled release). In conclusion, CBs from dissolved cellulose show promise in achieving controlled drug delivery.

Modulation and optimization of drug release from uncoated low density porous carrier based delivery system

The purpose of this research work was to explore an application of uncoated porous drug carrier prepared by single-step drug adsorption for a delivery system based on integration of floating and pulsatile principles intended for chronotherapy. This objective was achieved by utilizing 3(2) factorial design, solvent volume (X(1)) and drug amount (X(2)) as selected variables, for drug adsorption using solvents, methanol, and dichloromethane (DCM), of varying polarity. Nitrogen adsorption (N(2)), scanning electron microscopy of cross-sections, and atomic force microscopy were done to study adsorption patterns and their effect on release pattern. Drug release study was customized by performing for 6 h in acidic environment to mimic gastroretention followed by basic environment akin to transit phase. Correlation between porous data from mercury and N(2) adsorption was probably studied for the first time. Observed regression analysis values for pore volume, surface area, and drug release indicated the influence of selected variables. Total release range in acidic medium was 12.77-24.57% for methanol, 8.79-15.26% for DCM, and final release of 69.45-92.23% for methanol, and 60.16-99.99% for DCM influenced by varying internal geometries was observed. Present form of drug delivery system devoid of any additives/excipients influencing drug release shows distinct behavior from other approaches/technologies in chronotherapy by (a) observing desired low drug release (8%) in acidic medium, (b) overcoming the limitations of process variables caused by multiple formulation steps and different characteristic polymers, (c) reducing time consumption due to single step process, and (d) extending as controlled/extended release.

The Influence of Thermal Treatment on the Release Behavior of Diclofenac Sodium from Acrylic Matrices

The objective of this work was to investigate the effect of thermal treating on the release rate of diclofenac sodium from Eudragit RS and Eudragit RL matrices. Eudragit RS and RL are nonswelling polymers that have a low glass transition (Tg) temperature. The matrices were thermally treated at different temperatures (40, 50, 60, and 70 degrees C) for different periods of times (2, 5, and 24 h). The results showed that thermal treating at temperatures less than the Tg of the polymer has no effect on the release of the drug, whereas heat-treating at temperatures higher than the Tg decreases the release rate of diclofenac sodium from matrices. It was shown that the duration of heat treatment was also an important factor in controlling the release rate of diclofenac sodium from Eudragit matrices. The results showed that an increase in the duration of heat treatment from 2 h to 24 h resulted in a reduction in the release rate of the drug. Scanning electron microscopy of the cross section of the tablet before and after heat treating showed that the tablets were deformed and fused into a continuous and homogeneous structure after heat treating. Thermally treated tablets demonstrated fewer surface defects than did nonthermally treated tablets. These structural changes in the tablet compacts resulted in a matrix structure that decreased the release rate of the diclofenac sodium from Eudragit matrices.

The kinetics of pentoxifylline release from drug-loaded hydroxyapatite implants

Hydroxyapatite (HAP) was synthesized by the aqueous precipitation method from CaO and H3 PO4 as the reagents. The HAP powders, either subjected or not subjected to preliminary calcination, were mixed with a pore-creating medium and isostatically shaped at a pressure of 350 MPa to form cylindrical samples. A natural product such as flour served as a pore-creating medium. Sintering was performed in the air, at 1200 or 1250 degrees C. The employed procedure allowed for achieving microporous materials of pore sizes ranging from 0.1 to 15 microm and with open porosity values of 23-44%. It was demonstrated that the porosity of the obtained materials depended mainly on the amount of the added pore-creating medium and the temperature of sintering. The implants, shaped as hollow cylinders, were filled with 50 mg of pentoxifylline (PTX) as a model drug. Internal wells for drug placement were drilled in the samples using a high precision drill. The drug release study was performed in pH = 7.35 phosphate buffer, at 37 degrees C. The results showed that the amount and time of PTX release, as well as the lag time were mainly controlled by the open porosity of the carriers.

Porous cellulose matrices containing lipophilic release modifiers--a potential oral extended-release system

A multiple-unit extended-release matrix preparation was prepared by the incorporation of a hydrophilic drug (paracetamol) and lipophilic release modifiers (cetyl alcohol and paraffin) into porous cellulose matrices. The incorporation was performed using a one-step melt method. The in vitro drug release could be extended up to at least 16 h. The release rate could be controlled by varying the ratio of cetyl alcohol to paraffin. The porosity of the matrix during release increased to a larger extent than explainable by dissolution of the drug substance. This increase in porosity appears to be caused by swelling of the cellulose in combination with some erosion of the matrix material.

Fluorometric Studies of Pyrene Adsorption on Porous Crystalline Cellulose

Pyrene crystals were physically mixed with either porous crystalline cellulose (PCC) or octa decyl siryl silica-80Tm (ODS). Solid-state fluorescence spectra of pyrene were analyzed to estimate the interaction between pyrene and porous materials. Pyrene monomer emission was observed at 398 nm immediately after being mixed with PCC, while pyrene crystals showed only excimer emission at 475 nm, indicating that the pyrene molecules adsorbed onto the PCC surface in a short period. For the PCC system containing 1.0% pyrene, long-term storage caused an increase in the intensity of excimer-like emission peak at 477 nm accompanied by a decrease in the intensity of monomer emission peak at 398 nm. For the ODS system containing 1.0% pyrene, spectrometric changes were similar to those for the PCC system. In the process of interaction formation between pyrene and an additive, a two-step mechanism was proposed, i.e., the adsorption of pyrene molecules onto the surface of porous additives, and the formation of a ground state dimer of pyrene. The formation of dimeric pyrene could be associated with the surface polarity of additives. Copyright 1998 Academic Press.