SPECTROPHOTOMETRIC ANALYSIS OF TABLETS OF PIROXICAM USING MELTED NIACINAMIDE AS SOLVENT (MIXED SOLVENCY CONCEPT)

In the present research a novel method for spectrophotometric estimation of piroxicam tablets using melted niacinamide as solvent was developed. The main objective of the research is to show that solids also possess solubilizing power. The current study deals with a novel spectrophotometric analytical technique for quantitative estimation of piroxicam in tablets using melted niacinamide as solvent. According to the theory proposed by Maheshwari, each & every substance possesses solubilising power; the substance may be a gas, solid or liquid. Niacinamide imbibes large solubilizing power to piroxicam and having approximate solubility 110 mg per gm of melted niacinamide (135°C) whereas aqueous solubility of piroxicam is 0.40 mg/ml at room temperature. Niacinamide does not interfere above 300 nm in the spectrophotometric analysis. Calibration curve of piroxicam was plotted by recording the absorbances of standard solutions of the drug (5, 10, 15, 20 and 25 microgram/ml). The absorbances were observed at 358 nm against respective reagent blanks. The percent label claims were found very close to 100.0 (99.08 ±1.764 and 100.93 ±1.303) indicating the accuracy of the proposed method. Percent recoveries estimated by the proposed method are close to 100.0 (99.92 ±1.605 to 101.74 ±1.663) with signicant low values of percent coefcient of variation and standard error. Thus, it may be concluded that the proposed method is simple, safe, and precise, and excludes the use of toxic organic solvents.


EXPERIMENTAL METHODS SOLUBILITY STUDIES -
The solubility of piroxicam at room temperature in water was found to be 0.40 mg/ml. Using an approximate method of solubility determination, it was found that more than 110 mg piroxicam was dissolved in one gram of melted niacinamide (at 135°C).
CALIBRATION CURVE -10 gm niacinamide was taken in a 500ml volumetric ask and it was heated carefully on the heating mantle. As soon as niacinamide was melted, 50 mg of standard sample of piroxicam was added and the ask was shaken to dissolve the drug. Intermittent heating and shaking were done for the complete dissolution of the drug. Then, 400 ml of hot distilled water (90°C) was transferred carefully (little at a time) to the volumetric ask and the contents are shaken for about 5 minutes. The ask was allowed to cool to attain the room temperature. Then, the volume was made up 500ml with distilled water. This was the stock solution of the drug (100 µg/ml). By appropriate dilution of this stock solution with distilled water, standard solutions of the drug (10, 20, 30, 40, 50 µg/ml) were prepared and their absorbances were noted at 358 nm against the respective reagent blanks and using these values, the calibration curve was obtained.

SPECTROPHOTOMETRIC ANALYSIS OF TABLETS OF PIROXICAM USING MELTED NIACINAMIDE AS SOLVENT (MIXED SOLVENCY CONCEPT)
Original Research Paper

Pharmacy
In the present research work, a novel method for spectrophotometric estimation of piroxicam tablets using melted niacinamide as solvent was developed. The main objective of the research is to show that solids also possess solubilizing power. The current study deals with a novel spectrophotometric analytical technique for quantitative estimation of piroxicam in tablets using melted niacinamide as solvent. According to the theory proposed by Maheshwari, each & every substance possesses solubilising power; the substance may be a gas, solid or liquid. Niacinamide imbibes large solubilizing power to piroxicam and having approximate solubility 110 mg per gm of melted niacinamide (135°C) whereas aqueous solubility of piroxicam is 0.40 mg/ml at room temperature. Niacinamide does not interfere above 300 nm in the spectrophotometric analysis. Calibration curve of piroxicam was plotted by recording the absorbances of standard solutions of the drug (5, 10, 15, 20 and 25 microgram/ml). The absorbances were observed at 358 nm against respective reagent blanks. The percent label claims were found very close to 100.0 (99.08 ±1.764 and 100.93 ±1.303) indicating the accuracy of the proposed method. Percent recoveries estimated by the proposed method are close to 100.0 (99.92 ±1.605 to 101.74 ±1.663) with signicant low values of percent coefcient of variation and standard error. Thus, it may be concluded that the proposed method is simple, safe, and precise, and excludes the use of toxic organic solvents.

RESULTS AND DISCUSSION
The aqueous solubility of piroxicam at room temperature was 0.40 mg/ml whereas the solubility of piroxicam in melted niacinamide was found to be 110 mg per gram of melted niacinamide at 135°C. It is evident from Table I that (Table I & II).

CONCLUSION
The mixed solvency concept can be successfully employed in increasing solubility and analytical estimation of various drugs. A large number of poorly water-soluble drugs having absorption maxima above 300 nm can be tried for estimation by this method. Such solid as solvent (niacinamide) can be used in place of costly and toxic organic solvents. Then, 400 ml of hot (90°C) distilled water was carefully (little at a time) added to the ask and the ask was shaken for about 5 minutes. Then, the ask was allowed to cool to attain room temperature and the volume was made up to the mark with distilled water. After ltration through Whatman lter paper no.41, 5 ml ltrate was diluted to 50 ml with distilled water and the absorbance was noted at 358 nm against reagent blank. Using the calibration curve the drug, content was computed. Similar treatment was done for formulation II. All analysis were performed thrice.
PROPOSED METHOD -20 tablets of piroxicam, formulation I were weighed and crushed to get a ne powder. Ten grams of niacinamide was kept in a 500 ml volumetric ask and the ask was carefully heated on the heating mantle to melt the niacinamide. After complete melting of niacinamide, tablet powder equivalent to 50mg of the drug was transferred to the ask and the ask was shaken for 10 minutes with intermittent heating and shaking.

RECOVERY STUDIES -
Recovery studies taking 15 mg and 30 mg of pure drug as spiked drug together with pre-analysed tablet powder equivalent to 50 mg drug) were performed using the same proposed method.