Preparation and in Vitro evaluation of mefenamic Acid Sustained Release Beads

Formulation and evaluation of time-controlled triple-concentric mefenamic acid tablets for rheumatoid arthritis

A triple-concentric time-controlled release mefenamic acid (MA) tablet was developed using Carbopol and Ethocel polymers. The burst dose was programed to release immediately after an ingestion of tablet to be followed by a lag period of 2-4 h, and thereafter an 8 h controlled release of MA from core tablet. Core tablets were prepared using Carbopols 971P, 974P, 71G or 907 at various concentrations. The core tablet provided a controlled release of MA and the release rate decreased with increasing polymer concentration. Highly cross-linked Carbopol 974P released MA at a faster rate compared to release from Carbopol 971P with medium degree of cross-linking. Carbopols 71G and 971P exhibited essentially similar release rates. Carbopol 907, a linear polymer, showed fastest release of MA. The extent of uptake of dissolution medium by core tablets was inversely related to the rate of release of MA from the tablets. Compression coating of core tablet with Ethocel provided the lag period to delay release of MA from core tablet. Increase in lateral coating thickness decreased MA release and increased lag period. Compression forces applied during compression coating with Ethocel for lag period, and immediate-release MA coating for burst release did not affect the integrity of core tablet.

Investigations on mefenamic acid sustained release tablets with water-insoluble gel

Mefenamic acid (MA) has analgesic, anti-inflammatory and antipyretic properties. Available conventional dosage forms are capsules and film-coated tablets. No commercial sustained release preparation of MA exists in the market. The usual oral dose is 250 or 500 mg and reported half-life is 2 h. Sodium alginate (NaAL) is the sodium salt of alginic acid, a natural polysaccharide extracted from marine brown algae. It has the ability to form a water-insoluble gel with a bivalent metal ions as calcium. Therefore, NaAL has been studied for preparing sustained release formulations in pharmaceutical technology. In this study, tablet formulations containing different ratios of NaAL and calcium gluconate (CaGL) were prepared by direct compression method. In vitro release studies were carried out using USP 23 basket method and release data were kinetically evaluated. According to release studies, it can be emphasized that NaAL and CaGL can be used for design of sustained release preparation of MA.

Extrusion and spheronization in the development of oral controlled-release dosage forms

The concept of multiparticulate dosage forms was introduced in the 1950s. With the increasing use of multiparticulate controlled release (CR) oral dosage forms, in recent times there has been a rise in interest in the methods of preparing these dosage forms. A method that has gained increased usage over the past few years is that of extrusion and spheronization. It has been extensively explored as a potential technique and also as a future method of choice for preparation of multiparticulate CR dosage forms. In this review an attempt is made to outline the general process of extrusion and spheronization and to assess its importance in the development of multiparticulate CR oral dosage forms.

Effect of coating of aluminum carboxymethylcellulose beads on the release and bioavailability of diclofenac sodium

The production of spheres loaded with diclofenac sodium by the cross linking technique was achieved. The hydrophilic polymer sodium carboxymethylcellulose (Na-CMC) which gels in the presence of a cross linking agent, aluminum chloride (AlCl3), was used as a matrix forming agent for the bead production. To obtain a regular and uniform rate of drug release, the produced beads were coated with sodium alginate to increase the pathway of the diffused medium. Two processing variables were studied, the flocculating agent concentration (20, 40 and 60% w/v) and different coating times (15, 30 and 60 min). The results show that the higher concentrations of aluminum chloride (40 and 60% w/v) produced more uniform and rounded beads than that prepared using 20% w/v salt. The particle size of the core beads decreased insignificantly (P > 0.05) as the flocculating agent concentration increased. The coating time did not affect the particle size of the coated beads within the same concentration of aluminum chloride. The dissolution studies showed that the release rate of diclofenac sodium from the core beads increased with the increase of AlCl3 concentration and that the rate of drug release was markedly reduced after the coating of the core beads with Na-alginate. The results also show a linear relationship for drug release over a 4-5 h period from the core beads where it showed a longer straight line relationship (7 h) for the coated beads. The coating of the Al-CMC beads, prepared using 60% w/v AlCl3.6H2O, with 2% w/v aqueous solution of Na-alginate resulted in a significant (P < 0.05) sustaining action of the Al-CMC beads as indicated by the shift in Tmax from 1.7 +/- 0.84 to 3 +/- 0.71 h and the prolongation of the MRT from 7.86 +/- 0.54 to 10.82 +/- 1.33 h. The Cmax increased significantly from 5.43 +/- 2.91 to 11.66 +/- 6.18 micrograms/ml while the AUC0-->24 increased insignificantly (P > 0.05) from 39.82 +/- 26.61 to 57.92 +/- 25.58 micrograms h/ml resulting in a relative bioavailability of 145.45% relative to Al-CMC beads.