Solubilization of tenoxicam via different techniques

Document Type : Original Article

Authors

1 Department of Pharmaceutics, Faculty of Pharmacy, Al-zhar University

2 Department of Pharmaceutics, Faculty of Pharmacy, Assiut University, Egypt

Abstract

In this study, several techniques were employed to improve the aq. soly. of tenoxicam.  These techniques include co-​solvency, micellar solubilization and solid dispersions using different water-​sol. polymers.  The aq. soly. of tenoxicam in presence of 10​% of formamide, DMF and DMSO was enhanced about 4.5, 3.1 and 2.8 times, resp.  In addn., the results show that the hydroxylated cosolvents (glycerol, PG, PPG, PEG 200, PEG 300, PEG 400 and PEG 600) just potentiated the aq. soly. of the drug.  Several classes of non-​ionic surfactants were studied for their solubilizing action on tenoxicam.  These classes were polysorbates (Tweens)​, polyoxyethylene alkylethers (Brijs) and polyoxyethylene stearates (Myrjs)​.  Tween 80 exhibited a better solubilizing capacity on tenoxicam than other investigated tweens and they could be arranged according to their solubilizing capacity on the drug and the distribution coeff. of the drug between their micelles as: Tween 80 > Tween 60 > Tween 40.  It is clearly evident that the solubilizing effect of these micellar forming agents increases as the hydrophobic chain length of the surfactant increases.  In addn., Brij 35 exhibited a higher solubilizing capacity on the drug than Brij 58.  Furthermore, Myrj 59 exhibited higher solubilizing power on tenoxicam compared to Myrj 53 and Myrj 52.  These results indicate the relationship between the aq. soly. of the drug in presence of the above tested surfactants and its distribution coeff. between micellar and aq. phases.  The dissoln. rate of tenoxicam in presence of PEG 4000 and PVP 40000 in its solid dispersions was improved esp. with PVP 40000 (in a drug: polymer ratio 1:9)​.  IR, DSC and x-​ray diffraction studies were conducted to investigate the mechanism responsible for this improvement