Formulation and characterization of nystatin gel

The main objective of this research is to develop and characterize a series of carbopol 934 (CP) hydroxypropyl methylcellulose (HPMC) and a combination of carbopol-HPMC as a gel base for topical delivery of nystatin. The drug level was held constant at 1.72% w/w and the level of propylene glycol which is used as a co-solvent and penetration enhancer was also kept constant at 2% w/w. The total level of the polymer was held constant at 1.5% w/w as a single polymer or combination of two polymers. The polymers combination selected were: carbopol 934 to HPMC at a ratio of 0:1, 1:0, 1:2, 2:1 and 1:1. The batch size was 500 g and triethanolamine was used to adjust the pH of the gel. The rheological study showed that formulation containing combination of 2 carbopol and 1 HPMC ratio gave the highest viscosity, and exhibited an apparent pseudoplastic thixotropic behavior. The diffusion study indicated that gel formulation containing carbopol-HPMC at a ratio of 2:1 gave the highest percent drug diffusion compared to formulation containing low carbopol to HPMC ratio, carbopol alone or HPMC alone. Both in-vitro release and rheological study indicated that carbopol-HPMC had the best gel strength, physical properties and ability to diffuse the drug than carbopol or HPMC alone. The results obtained in this study demonstrated that the combination of carbopol and hydroxypropyl methylcellulose can be used as a gel vehicle for nystatin topical application.

Effect of hydrodynamic environment on tablet dissolution using flow-through dissolution apparatus

The main objective of this research is to investigate the principles underlying the dissolution process, study the phenomena of drug release in laminar flow, and better understand the effect of hydrodynamic condition on drug dissolution, in order to predict drug dissolution from a solid dosage form. Two drug models were selected, theophylline (Class I) and naproxen (Class II), and were formulated into conventional tablets containing 105 mg theophylline or 300 mg naproxen using wet granulation method. Additionally theophylline (105 mg) and naproxen (300 mg) matrices containing 30hydroxypropylmethylcellulose (HPMC) polymer were prepared by direct compression and tested for dissolution using both USP II and IV dissolution apparatus. Tablets were tested for dissolution (USP IV) using different cell diameter, flow rate, and different position of the tablet inside the cell. In general, the drug dissolution at a given time is a direct function of the flow rate, increasing the flow rate increases drug release. The use of a small cell resulted in faster drug dissolution and higher Reynold's Number than using a large cell. Tablet position in the cell, also has an effect on drug dissolution, inserting the tablet in a horizontal position inside the cell gave faster dissolution than a vertical position. The hydrodynamic conditions did not affect the drug dissolution from HPMC controlled release tablets indicating that the drug dissolution is controlled by the matrix. An equation to predict drug dissolution from conventional tablets was established: Sh=-21.36+10.58Re(1/2) where R2=0.98. This study demonstrated that hydrodynamic conditions, and type of dissolution testing apparatus used have an effect on dissolution rate, mass transfer rate, and film thickness underlying dissolution process.

In-vitro evaluation of sustained release ibuprofen microspheres

Microspheres for oral use have been employed to target and to sustain the release of the drug. The objective of this study was to use the melt dispersion technique and aqueous vehicle to entrap ibuprofen into wax carrier (carnauba wax) with the aid of surfactant (Pluronic L-62). The effects of different levels of Pluronic L-62, stirring speed, and ibuprofen levels, as well as the in-vitro release rate of ibuprofen were evaluated. The in-vitro dissolution of ibuprofen in phosphate buffer pH 7.2 showed that microspheres prepared with low amount of drug (1.5 g) released 58.1 percent of ibuprofen after 6 hours, while microspheres prepared with high amount of drug (6.0 g) released only 38.9 percent of ibuprofen. Microsphere formulations prepared by using aqueous vehicle were spherical and of smooth surface. In general the melt dispersion technique was a successful method for preparing sustained release ibuprofen microspheres

Sustained release phenylpropanolamine hydrochloride from ATO 888 matrix

Sustained release phenylpropanolamine HCl tablets were prepared with compritol as a retardant material. The effects of varying wax levels and methods of matrix formation on drug release were investigated. Also the compaction profiles were recorded for all formulations. The amount of drug in the formula was held constant (10 per cent w/w), while the wax level was varied from 10 per cent to 50 per cent w/w. Two methods were used for the preparation of drug: wax systems; physical mixture and solid dispersion. The drug release from tablets containing 10 per cent Compritol and prepared by solid dispersion was 97 per cent after six hours of testing dissolution. Tablets prepared with 30 per cent wax released 72 per cent of the drug, while tablets containing 50 per cent wax released only 30 per cent of the drug after six hours. Tablets prepared by physical mixture gave higher drug release than tablets prepared by solid dispersion method. The incorporation of Compritol decreased the ejection forces of tablets during compaction. The drug release from tablets prepared by solid dispersion followed the diffusion controlled model described by Higuchi for inert porous matrix

Acetaminophen-alginate spheres prepared by cross linking technology

Spheres of acetaminophen (APAP) were prepared via the cross linking agglomeration technique and were successfully compacted into tablets. The drug load in all formulations was 20w/v, the cross linking agent varied from 1w/v to 20w/v, the polymer levels varied from 1w/v to 4w/v and the residence time from 3 to 60 minutes. The data obtained showed that increasing the concentration of the cross linking agent to 5w/v or more showed no reduction in drug release rate. Also varying the residence time of the spheres in the cross linking solution showed no detectable differences in the drug release from spheres. Formulations prepared with 3w/v and or 4w/v polymer level showed higher drug release than formulation prepared with lower polymer levels

Physicochemical characterization of acetaminophen-ethylcellulose solid dispersion

In this study, ethylcellulose was evaluated as a carrier for the preparation of sustained release of acetaminophen via solid dispersion technique. Physical mixture at the same level of acetaminophen and ethylcellulose was prepared. Differential scanning calorimetry and scanning electron microscope were used to characterize the physical properties of the various systems and to determine if there is possible interaction between acetaminophen and ethylcellulose