Effect of Drug Loading and Molecular Weight of Cellulose Acetate Propionate on the Release Characteristics of Theophylline Microspheres (original) (raw)
Related papers
2011
Purpose: To formulate theophylline microspheres with cellulose acetate using solvent evaporation method and evaluate the effect of various processing factors on their characteristics. Methods: Microspheres containing theophylline were prepared with a hydrophilic, biocompatible polymer- cellulose acetate- by an emulsion solvent evaporation technique using an acetone/liquid paraffin system containing Span 80 as a surfactant. The effect of processing factors, e.g., varying drug/polymer ratio (1:1, 1:2, 1:3) and temperature (10 and 35 °C) on microsphere characteristics and drug release were examined. Similarly, microspheres with a drug/polymer ratio of 1:3 incorporating Span 20 were also also prepared and evaluated. Results: The microspheres were white, free-flowing and spherical. The yield varied from 73.0 to 87.5 % while entrapment efficiency was in the region of 71.8 to 92.4 %. High drug/polymer ratio, Span 80 (surfactant) and processing temperature between 10 and 30 °C produced form...
Tropical Journal of Pharmaceutical Research, 2011
Purpose: To formulate theophylline microspheres with cellulose acetate using solvent evaporation method and evaluate the effect of various processing factors on their characteristics. Methods: Microspheres containing theophylline were prepared with a hydrophilic, biocompatible polymer-cellulose acetate-by an emulsion solvent evaporation technique using an acetone/liquid paraffin system containing Span 80 as a surfactant. The effect of processing factors, e.g., varying drug/polymer ratio (1:1, 1:2, 1:3) and temperature (10 and 35 °C) on microsphere characteristics and drug release were examined. Similarly, microspheres with a drug/polymer ratio of 1:3 incorporating Span 20 were also also prepared and evaluated. Results: The microspheres were white, free-flowing and spherical. The yield varied from 73.0 to 87.5 % while entrapment efficiency was in the region of 71.8 to 92.4 %. High drug/polymer ratio, Span 80 (surfactant) and processing temperature between 10 and 30 °C produced formulations with better drug entrapment efficiency. High drug/polymer ratio, low processing temperature and low HLB value of surfactant enhanced the sustained drug release characteristics of the microspheres. Conclusion: The combination of three suitable factors-Span mixture (with HLB value of 4.3), processing temperature of 10 °C and drug/polymer ratio of 1:3-produced a suitable controlled release theophilline microsphere formulation which could be effective for the management of asthma.
Pharmaceutical Development and Technology, 2011
Altering the combined hydrophilic-lipophilic balance (CHLB), by varying the ratio of dual surfactants, on formulation parameters and in vitro drug release of ethyl cellulose microspheres was examined. Theophylline, a xanthine bronchodilator was used to model controlled release owing to its narrow therapeutic index. Microspheres were prepared using different ratios of dual surfactant in an emulsion-solvent evaporation process. Drug loading, encapsulation efficiency, particle size distribution, and geometric mean diameters were evaluated. Drug release was evaluated using several kinetic models including zero and first order, Higuchi square root, and Hixson-Crowell. Microspheres presented as mostly spherical particles and diffusional drug release was affected by microsphere construction. For this novel, dual surfactant system the microsphere matrix is a hydrophobic polymer and the release rate may be modulated with variation in ratio of dual surfactants. Dissolution data followed the Higuchi model and supports the formation of a monolithic microsphere matrix that releases theophylline by Fickian diffusion. Dual surfactants for preparation of microspheres are an inadequately studied research area that offers another means to modulate particle size and drug release. For the current study microspheres prepared with surfactant ratios of Span 65: Tween 40 between 3:1 and 2:1 provided the best control of size and drug release.
Brazilian Journal of Pharmaceutical Sciences, 2016
The present study describes the development of theophylline microcapsules by a non-solvent addition method and the effect of plasticizer addition on microencapsulation. The release was studied in distilled water and the data were analysed by various mathematical models for determining the mechanism of release. Prepared microcapsules were found to be spherical, free flowing and having more than 80% entrapped drug. The polymer - cellulose acetate phthalate and plasticizer - polyethylene glycol was considered to be affecting the properties of microcapsules including drug release (time for 50% drug release, T50). The formulation with the highest proportion of polymer and without plasticizer (F3) showed the slowest release with T50 = 4.3 h, while the formulation with lower proportion of polymer and 20% (w/w) plasticizer (F13 &14) showed the fastest release of drug with T50 values of 1.2 h and 1.3 h, respectively. The drug release from most of the formulations was found to be following Hi...
PubMed, 2010
The objective of the present investigation was to design a sustained release floating microcapsules of theophylline using two polymers of different permeability characteristics; Eudragit RL 100 (Eu RL) and cellulose acetate butyrate (CAB) using the oil-in-oil emulsion solvent evaporation method. Polymers were used separately and in combination to prepare different microcapsules. The effect of drug-polymer interaction was studied for each of the polymers and for their combination. Encapsulation efficiency, the yield, particle size, floating capability, morphology of microspheres, powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) were evaluated. The in vitro release studies were performed in PH 1.2 and 7.4. The optimized drug to polymer ratios was found to be 4:1 (F(2)) and 0.75:1 (F'(2)) with Eu RL and CAB, respectively. The best drug to polymer ratio in mix formulation was 4:1:1 (theophylline: Eu RL: CAB ratio). Production yield, loading efficiencies, and particle size of F(2) and F'(2) were found to be 59.14% and 45.39%, 73.93% and 95.87%, 372 and 273 micron, respectively. Microsphere prepared with CAB showed the best floating ability (80.3 ± 4.02% buoyancy) in 0.1 M HCl for over 12 h. The XRD and DSC showed that theophylline in the drug loaded microspheres was stable and in crystaline form. Microparticles prepared using blend of Eu RL and CAB polymers indicated more sustained pattern than the commercial tablet (P<0.05). Drug loaded floating microballoons prepared of combination of Eu RL and CAB with 1:1 ratio were found to be a suitable delivery system for sustained release delivery of theophylline which contained lower amount of polymer contents in the microspheres.
Jordan Journal of Pharmaceutical Sciences, 2011
The objective of this study was to prepare and evaluate microparticles of Eudragit and Ethyl cellulose binary blend loaded with theophylline for controlled release. Microparticles were prepared by Phase separation method. The method is quite simple, rapid, and economical and does not imply the use of toxic organic solvents. Solid, discrete, reproducible free flowing microparticles were obtained. The yield of the microparticles was up to 92%. More than 85% of the isolated microparticles were of particle size range of 325 to 455 µm. The obtained angle of repose, % carr's index and tapped density values were well within the limits, indicating that prepared microparticles had smooth surface, free flowing and good packing properties. Scanning Electron Microscopy photographs and calculated sphericity factor confirms that the prepared formulations are spherical in nature. Prepared microparticles were sTab. and compatible, as confirmed by DSC and FT-IR studies. The prepared formulations were quantitatively analyzed for the amount of encapsulated drug. It was observed that there is no significant release of the drug at gastric pH. The drug release was controlled more than 12 h. Intestinal drug release from microparticles was studied and compared with the release behavior of commercially available oral formulation Duralyn CR 400. The release kinetics followed different transport mechanisms.
Iranian Journal of Basic Medical Sciences, 2012
The aim of this study was to formulate and evaluate microencapsulated controlled release preparations of theophylline using ethylcellulose as the retardant material with high entrapment efficiency. Microspheres were prepared by water-in-oil-in-oil (W/O1/O2) emulsion-solvent diffusion (ESD). A mixed solvent system consisting of acetonitrile and dichloromethane in a 1:1 ratio and light liquid paraffin were chosen as primary and secondary oil phases, respectively. In the current study formulations with different drug/polymer ratios were prepared and characterized by drug loading, loading efficiency, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The best drug to polymer ratio was 0.5:1 (F2 formulation). F2 Formulation showed 29.53% of entrapment, loading efficiency of 88.59%, and mean particle size of 757.01 µm. SEM studies showed that the microspheres were spherical. FTIR, SEM, XR...
Comparative Evaluation of Theophylline Microsphere prepared using Various Biodegradable Polymers
international journal of chemical sciences, 2008
The present investigation was to formulate theophylline loaded microspheres using different grade of chitosan, chitosan-sodium alginate and chitosan-albumin by the following methods such as phase separation emulsification, modified ionotropic gelation and heat stabilization method. The prepared microspheres were evaluated in terms of drug content, incorporation efficiency, micromeritic studies, moisture content and in vitro drug release profile. Chitosan-sodium alginate combination produced microspheres with spherical, smooth surface and frees flowing. It exhibited incorporation efficiency above 75% and size range between 999-994 µm. The drug release from the microspheres follows first order kinetics and the mechanism is Higguchi's diffusion. Theophylline loaded microspheres prepared from Chitosan-sodium alginate combination exhibited good sustained release characteristics and was found suitable for chronic obstructive pulmonary disease (COPD) and nocturnal asthma.
Influence of cellulose polymers type on in vitro controlled release tablets containing theophylline
Revista Brasileira de Ciências Farmacêuticas, 2007
In this study, the effect of ethylcellulose (EC) and 6 types of hydroxypropylmethylcellulose (Methocel ® K100M, K100MPRCR, K15MPRCR, K4MPRCR, K4M PR and E4MCR) on release profile of theophylline from matrix tablets was evaluated. Formulations tablets were prepared by either wet granulation or direct compression technique. The tablets were evaluated for physical characteristics and in vitro release of drug was performed as described in USP 30 ed. (Test 3). All formulations with cellulose polymer produced tablets easily and with physicals characteristics in accordance with official limits. Drug dissolution tests showed that formulations with 15% of Methocel ® K4MPR, 15% of Methocel ® K4MPRCR and 30% of Ethocel ® N10STD, obtained by direct compression method, complied with official specifications, in terms of release profile and diffusion was the main mechanism involved in theophylline delivery.