An Investigation on the Effect of Polyethylene Oxide Concentration and Particle Size in Modulating Theophylline Release from Tablet Matrices

Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20-45, 45-90, 90-180 and 180-425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles.

An Investigation on the Effect of Polyethylene Oxide Concentration and Particle Size in Modulating Theophylline Release from Tablet Matrices

Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20-45, 45-90, 90-180 and 180-425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles.

Bimodal gastroretentive drug delivery systems of lamotrigine: formulation and evaluation

Gastroretentive bimodal drug delivery systems of lamotrigine were developed using immediate release and extended release segments incorporated in a hydroxypropyl methylcellulose capsule and in vitro and in vivo evaluations were conducted. In vivo radiographic studies were carried out for the optimized formulation in healthy human volunteers with replacement of drug polymer complex by barium sulphate and the floating time was noted. Here the immediate release segment worked as loading dose and extended release segment as maintenance dose. The results of release studies of formulations with hydrophillic matrix to formulations with dual matrix hydroxypropyl methylcellulose acetate succinate shown that as the percentage of polymer increased, the release decreased. Selected formulation F2 having F-Melt has successfully released the drug within one hour and hydrophillic matrix composing polyethylene oxide with 5% hydroxypropyl methylcellulose acetate succinate showed a lag time of one hour and then extended its release up to 12th hour with 99.59% drug release following zero order kinetics with R(2) value of 0.989. The Korsmeyer-Peppas equation showed the R(2) value to be 0.941 and n value was 1.606 following non-Fickian diffusion pattern with supercase II relaxation mechanism. Here from extended release tablet the drug released slowly from the matrix while floating.

Designing of the mucoadhesive intravaginal spermicidal films

A mucoadhesive drug delivery system for local delivery of metronidazole through vaginal route was formulated. Films were prepared by solvent evaporation method using various compositions of Carbopol, hydroxypropylmethylcellulose, chitosan, Polyox and propylene glycol. The films were evaluated for their weight, thickness, surface pH, folding endurance, mechanical, drug content uniformity, in vitro drug release, swelling, gelling and mucoadhesion property. All the films possess satisfactory film characteristics. Films made of Polyox found to possess acceptable, physicochemical, mechanical, gelling and mucoadhesion property for delivery of metronidazole.

Evaluation of polyoxyethylene homopolymers for buccal bioadhesive drug delivery device formulations

Our objective was to evaluate the application of polyoxyethylene homopolymers in buccal bioadhesive drug (BBD) delivery device formulations. The bioadhesive strength of four different molecular weight (MW) polyoxyethylene polymers was measured by Instron tensile tester using glass plate and bovine sublingual tissue as substrate surfaces. Several BBD device formulations containing polyoxyethylene polymer (MW 7,000,000) were prepared by direct compression and compression molding processes. The prepared BBD devices were evaluated for their elasticity, in vitro adhesion and drug release characteristics. The in vivo bioadhesion characteristics of a placebo compression molded device were examined in 3 adult healthy male beagle dogs. The bioadhesive strength of polyoxyethylene polymers appeared to be directly related to their molecular weights. When bovine sublingual mucosa or a glass plate was used as model mucosal substrate surface, the rank order of bioadhesive strength of different molecular weight polyoxyethylene polymers was similar. The bioadhesive strength of devices prepared by the compression molding process was greater than those prepared by direct compression, but the kinetics of drug release were independent of the process used for the preparation of the devices. The drug release and the bioadhesive strength of the similarly prepared device formulations appeared to be dependent on the drug:polymer ratios. The elasticity of the BBD devices prepared by compression molding was improved by the inclusion of polyisobutylene polymer in the formulations. When adhered to the oral cavity of the dogs, the compression molded placebo BBD device exhibited adhesion for at least 4 hours and appeared to show no signs of local irritation. In conclusion, BBD devices containing polyoxyethylene polymer (MW 7,000,000) can be prepared by direct compression or compression molding process in order to provide controlled drug release to the oral cavity while maintaining appropriate bioadhesive characteristics.