Validated HPLC Method for Concurrent Determination of Antipyrine, Carbamazepine, Furosemide and Phenytoin and its Application in Assessment of Drug Permeability through Caco-2 Cell Monolayers.

The present work explains the development and validation of a simple, rapid and sensitive liquid chromatographic method for the simultaneous determination of antipyrine (ANT), carbamazepine (CBZ), furosemide (FSD) and phenytoin (PHTN). Chromatographic analysis was carried out by a reversed phase technique on a C18 column, using water pH 3.0 and 50:50 mixtures of methanol and acetonitrile (58:42 v/v) as the mobile phase, at a flow-rate of 1.0 ml/min and a column temperature of 40°C. Detection was carried out at 205 nm for CBZ and PHTN and at 230 nm for ANT and FSD. The proposed method was evaluated for validation parameters including linearity, range, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ) and specificity. Elution of drugs ANT, FSD, PHTN, and CBZ was observed at 4.1, 5.1, 12.3 and 13.5 min, respectively. The method was found to be linear (R(2) ≥ 0.999) in the concentration range of 5-100 µM, with an acceptable accuracy and relative standard deviation. Results of intra- and inter-day validation (n=3) showed the method to be efficient for routine determination of these permeability markers in Caco-2 cell monolayer permeability studies. The method was successfully utilized for determination of standard compounds in Caco-2 permeability experiments.

Bioavailability of a lipidic formulation of curcumin in healthy human volunteers.

Numerous publications have reported the significant pharmacodynamic activity of Curcumin (CRM) despite low or undetectable levels in plasma. The objective of the present study was to perform a detailed pharmacokinetic evaluation of CRM after the oral administration of a highly bioavailable lipidic formulation of CRM (CRM-LF) in human subjects. Cmax, Tmax and AUC0-¥ were found to be 183.35 ± 37.54 ng/mL, 0.60 ± 0.05 h and 321.12 ± 25.55 ng/mL respectively, at a dose of 750 mg. The plasma profile clearly showed three distinct phases, viz., absorption, distribution and elimination. A close evaluation of the primary pharmacokinetic parameters provided valuable insight into the behavior of the CRM after absorption by CRM-LF. CRM-LF showed a lag time (Tlag) of 0.18 h (around 12 min). Pharmacokinetic modeling revealed that CRM-LF followed a two-compartment model with first order absorption, lag time and first order elimination. A high absorption rate constant (K01, 4.51/h) signifies that CRM-LF ensured rapid absorption of the CRM into the central compartment. This was followed by the distribution of CRM from the central to peripheral compartment (K12, 2.69/h). The rate of CRM transfer from the peripheral to central compartment (K21, 0.15/h) was slow. This encourages higher tissue levels of CRM as compared with plasma levels. The study provides an explanation of the therapeutic efficacy of CRM, despite very low/undetectable levels in the plasma.

Effect of counterions on the properties of amorphous atorvastatin salts.

Amorphous systems have gained importance as a tool for addressing delivery challenges of poorly water soluble drugs. A careful assessment of thermodynamic and kinetic behavior of amorphous form is necessary for successful use of amorphous form in drug delivery. The present study was undertaken to evaluate effect of monovalent sodium (Na(+); ATV Na), and bivalent calcium (Ca(2+); ATV Ca) and magnesium (Mg(2+); ATV Mg) counterions on properties of amorphous salts of atorvastatin (ATV) model drug. Amorphous form was generated from crystalline salts of ATV by spray drying, and characterized for glass transition temperature (T(g)), fragility and devitrification tendency. In addition, chemical stability of the amorphous salt forms was evaluated. Fragility was studied by calculating activation enthalpy for structural relaxation at T(g), from heating rate dependency of T(g). Density functional theory and relative pK(a)'s of counterions were evaluated to substantiate trend in glass transition temperature. T(g) of salts followed order: ATV Ca>ATV Mg>ATV Na. All salts were fragile to moderately fragile, with D value ranging between 9 and 16. Ease of devitrification followed the order: ATV Na∼ATV Mg≫ATV Ca, using isothermal crystallization and reduced crystallization temperature method. Chemical stability at 80°C showed higher degradation of amorphous ATV Ca (∼5%), while ATV Na and ATV Mg showed degradation of 1-2%. Overall, ATV Ca was better in terms of glass forming ability, higher T(g) and physical stability. The study has importance in selection of a suitable amorphous form, during early drug development phase.