Biomedical subjects

Nilüfer Yüksel

Publications and source records attributed to Nilüfer Yüksel.

5 recordsLinked to original sources

PubMed2006

Influence of aluminum tristearate and sucrose stearate as the dispersing agents on physical properties and release characteristics of eudragit RS microspheres.

The purpose of this research was to investigate the effects of different concentrations of polymer and sucrose stearate, aluminum tristearate as dispersing agents on microsphere properties and performance. The yield values of microspheres were over the 78%, and the encapsulation efficiencies were found to be approximately 73%. Particle sizes of microspheres prepared with aluminum tristearate were between 76 and 448 microm, while that of the microspheres containing sucrose stearate were between 521 and 2000 microm. Morphological and physicochemical properties of microspheres were investigated by scanning electron micrography and differential scanning calorimetry (DSC). DSC analysis indicated that verapamil hydrochloride formed a solid solution with acrylic polymers. In vitro release studies were performed using the flow-through cell method. While approximately 80% of drug was released from the microspheres containing aluminum tristearate in 480 minutes, the same amount of drug was released from microspheres containing sucrose stearate in only 60 minutes. Chemical structures and concentrations of the dispersing agents were clearly effective on the physical properties of microspheres and their drug-release characteristics.

Acrylic Resins↗

PubMed2005

Improved solubility and dissolution rate of piroxicam using gelucire 44/14 and labrasol.

Piroxicam is a nonsteroidal anti-inflammatory drug that is characterized by low solubility-high permeability. The present study was designed to improve the dissolution rate of piroxicam at the physiological pH's through its increased solubility by preparing semi-solid dispersions of drug using Gelucires and Labrasol. These excipients are essentially characterized by their melting points and HLB (hydrophilic-lipophilic balance) values. The dissolution tests of the preparations were performed in the media with different pH's. Differential scanning calorimetry (DSC), were used to examine the interaction between piroxicam and excipients. Gelucire 44/14 and Labrasol at the concentration of 15% w/v in water provided 20- and 50-fold increase in the solubility of piroxicam, respectively. The semi-solid dispersion containing 1/20 of drug/excipient mixture (20% Gelucire 44/14 and 80% Labrasol in w/w) produced the dissolution not less than 85% of piroxicam within 30 min in each dissolution media (simulated gastric fluid (SGF), pH 1.2; phosphate buffers, pH 4.5 and 6.8; and water). DSC analysis of this semi-solid dispersion indicated that there was no chemical reaction between the drug and excipients, and that a solid-state solution of piroxicam with excipient formed.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2003

Enhanced bioavailability of piroxicam using Gelucire 44/14 and labrasol: in vitro and in vivo evaluation.

Piroxicam is a non-steroidal anti-inflammatory drug that is characterized by low solubility and high permeability. The purpose of the study was to investigate the in vitro and in vivo performance of the semi-solid dispersion prepared with Gelucire 44/14 and Labrasol into hard gelatin capsules (GL) for enhancing the dissolution rate of the drug. The results were evaluated by comparing with pure piroxicam filled into hard gelatin capsules (PP) and a commercially available tablet dosage form containing a piroxicam:beta-cyclodextrin complex (CD). The in vitro dissolution testing of the dosage forms was performed in different media (simulated gastric fluid, pH 1.2; phosphate buffers, pH 4.5 and 6.8; and water). Amongst the dosage forms, GL provided at least 85% piroxicam dissolution within 30 min in each of the media, behaving like a fast-dissolving immediate release drug product. Oral bioavailability of 20 mg piroxicam in GL, CD, and PP was compared after administration of a single dose to eight healthy volunteers. Three treatments were administered in crossover fashion, separated by a washout period of 2 weeks. Piroxicam was monitored in plasma by high-performance liquid chromatography. The apparent rate of absorption of piroxicam from GL (Cmax=2.64 micrograms/ml, tmax=82.5 min) was significantly higher than that of the PP (Cmax=0.999 micrograms/ml, tmax=144 min) (P<0.05) and similar to that of CD (Cmax=2.44 micrograms/ml, tmax=120 min) (P>0.05). The relative bioavailability values as the ratios of mean total AUC for GL relative to PP and CD, were 221 and 98.6%. Piroxicam is characterized by a slow and gradual absorption via the oral route and this causes a delayed onset of therapeutic effect. Thus, plain piroxicam preparations are not indicated for analgesia. The results of the in vivo study revealed that the GL dosage form would be advantageous with regards to rapid onset of action, especially in various painful conditions where an acute analgesic effect is desired.

Adult↗

PubMed2003

Comparative evaluation of granules made with different binders by a fluidized bed method.

Granules were prepared using three different binders, pregelatinized starch (PGS), gelatin (GEL), and polyvinylpyrrolidone (K30) by a fluidized bed method. As a quantitative measurement of mechanical strength or abrasion resistance, granules were subjected to a friability test for certain periods of time, and friability indexes (FI) as a function of time were calculated. The data obtained were analyzed by applying standard mathematical models. According to the derived parameters of the logistic and Weibull models, which fit best to the data, mechanical strength of granules made with K30 was observed to be lower than that of the granules of PGS and GEL which have similar values of model parameters. Flow properties, consolidation, and compressibility behaviors of unfriabled (UFR) and friabled (FR) granules, which were selected based upon their Weibull time parameter, were investigated as comparative. The flow rate of granules decreased due to diminishing particle size depending on binder type and friability, but the values of angle of repose were within the acceptable limits. Regarding consolidation behavior, the change of relative density vs. the number of taps, i.e., packing rate for FR granules of GEL was slower than that of its UFR form, whereas FR granules of PGS and K30 showed faster change in relative density compared to their UFR forms. According to the parameters obtained from the Heckel equation, PGS and K30 were found to produce softer, more plastic and readily deformable granules than GEL, and the compressibility of their FR forms was not influenced negatively.

Drug Design↗

PubMedDate not supplied

Preparation and characterization of poly(D,L-lactic-co-glycolic Acid) microspheres containing flurbiprofen sodium.

This study aimed to prepare biodegradable microspheres containing flurbiprofen sodium, a nonsteroidal anti-inflammatory drug (NSAID), as the drug delivery system to the periodontal pocket. Microspheres were prepared from biodegradable copolymers of poly (D,L-lactic-co-glycolic acid) (PLGA) using solvent evaporation method. The effects of the different copolymers and amounts of polyvinyl alcohol (PVA) as a dispersing agent on characteristics of the microspheres were evaluated. Although there was no correlation between microsphere size and amount of PVA, an optimum PVA concentration was essential to achieve narrower size distributions of microspheres. As the concentration of PVA increased, the drug loading of the microspheres increased. The effect of PVA on drug loading was found to be statistically significant for those microspheres prepared from PLGA 50:50 (p < 0.05). Regarding copolymer composition, PLGA 85:15 provided higher drug loading into the microspheres than PLGA 50:50 (p < 0.05). The recoveries of microspheres (60-80%) were affected neither by different PVA concentrations nor by copolymer compositions (p > 0.05). According to the first-order release rate constants of the microspheres, the microspheres of PLGA 50:50 released the drug at the highest rate consistently, with the highest hydrophilicity of this copolymer.

Algorithms↗