[Formulation of immediate release lamotrigine tablets and bioequivalence study]

Lamotrigine tablets were compressed directly by means of Avicel PH102, sodium starch glycolate, magnesium stearate, Aerosil 200 and PVPK25. A rapid, sensitive and simple high-performance liquid chromatographic [HPLC] method for the determination of lamotrigine in plasma is described. The drug was extracted from one mL of each rabbits plasma sample, then it was transferred into a 15 mL tube fitted with a polyethylene cap, 1 mL acetonitrile were added to the sample, and the supernatant was injected into the HPLC system. The drug and the internal control [carbamazepine] were eluted from C18 Zorbax ODS [4.6x250mm, USA] column at ambient temperature with a mobile phase consisting of acetonitrile and 20mM potassium dihydrogen phosphate buffer [35:65, v/v] and adjusted to [pH 7] using 1N NaOH, at a flow rate of 1.5 ml min[-1] and the detector was monitored at 210 nm. Quantitation was achieved by measurement of the peak-area ratio of the drug to the internal standard and the lower limit of detection for malotrigine in plasma was 0.491 micro g ml[-1]. The intraday precision ranged from 0.801-7.692% [coefficient of variation] [CV] and accuracy [relative error%] ranged from 0.048-4.9 for all samples. The relative recoveries of lamotrigine ranged from 95.10 to 101.89%. The method was applied in studying the pharmacokinetics of lamotrigine administered orally to rabbits. This reliable micro-method would have application in pharmacokinetic studies of lamotrigine. The relative percentage bioavailability of prepared lamotrigine tablets with respect to the commercially available Lamictal [registered sign] tablets was 134.68%

Terbutaline sulphate hydrophilic matrix tablets

Terbutaline sulfate hydrophilic matrix tablets were prepared using different hydrophilic matrix forming polymers. Cellulosic polymers used were hydroxypropylmethyl cellulose [HPMC] 15 cps, 100 cps and 4000 cps. Other polymers were sodium alginate and xanthan gum each used in concentrations of 7, 14, and 28%. Combinations of HPMC with pectin were also used for the preparation of terbutaline sulfate hydrophilic matrix tablets. In vitro evaluation of the prepared tablets was performed by the determination of the hardness, friability and release profiles. Release of the prepared formulations was performed using USP Dissolution Tester Apparatus II. Results showed that terbutaline sulfate hydrophilic matrix tablets prepared using different polymers controlled the release of the water-soluble drug over an extended period of time. The release of terbutaline from tablets prepared using hydroxypropylmethyl cellulose of different viscosity grades showed marked decrease with the increase of the viscosity grade used, where after 8 hours 94.7%, 54.7% and 49.5% of the drug was released using HPMC 15 cps, HPMC 100 cps and HPMC 4000 cps, respectively. For tablets prepared using xanthan gum, increasing the concentration of xanthan gum showed a decrease in release of terbutaline sulfate, where increasing the concentration from 7% to 28% showed a decrease in release from 91.5% to 69.1% after 8 hours. Hydrophilic matrix tablets prepared using sodium alginate did not offer the desired control over drug release. Binary mixtures of hydroxypropylmethyl cellulose and pectin in different ratios optimized the release profile of terbutaline sulfate. It was found that increasing the ratio of pectin resulted in an increase in the release rate of the drug. Optimum release profile was achieved when the hydrophilic matrix tablet was prepared using HPMC 100cps and pectin in ratio of 4:1. Kinetic analysis of the release data showed that ideal zero order release was achieved for tablets prepared using this binary mixture