A Novel Method for the Investigation of Liquid/Liquid Distribution Coefficients and Interface Permeabilities Applied to the Water-Octanol-Drug System

Abstract

Our results show that the technique, which is available on any modern NMR spectrometer, is well suited to the measurement of distribution coefficients. The experiments present also new insight into the dynamics of the water-octanol interface itself and permit measurement of the interface permeability.

Novel in situ gel-forming solid dosage form (gfSDF) prepared by the simple syringe-based moulding: A screening study

“…Chromatographic separation of the two drugs was conducted using a Waters XTerra RP18 5 μm 3.9x150 mm reverse phase column, using a mobile phase composed of methanol (60%) and water (40%) with 0.1% of acetic acid (flow rate of 0.8 mL/min, injection volume 10 μL). CHL was detected at the wavelength of 278 nm (Satinski et al, 2006) and IBU at 264 nm (Stein et al, 2011;Zhu et al, 2005). Calibration curves for both drugs were prepared at their specific wavelengths of detection (coefficient of determination R 2 ≥ 0.999).…”

“…Ibuprofen (IBU) was chosen as model of anti-inflammatory drug ( Fig. 1 reports its chemical structure together with some of its physicochemical properties (Drugbank, 2017b;Stein et al, 2011)) because of its well-known, effective, safe and well-tolerated anti-inflammatory activities (Pierce and Voss, 2010). In this work, shape of the solid dosage form as well as the drugs chosen makes this formulation most suited for vaginal delivery, but the method can be easily adapted in order to obtain tablet (for oral use), suppositories (for rectal therapy) as well as thin sheets (for plaster in skin therapy) varying also the choice of the APIs.…”

Origin and correction of magnetic field inhomogeneity at the interface in biphasic NMR samples

“…Biphasic phenomenon have been studied to understand reaction kinetics [1], equilibria [2], partition coefficients [3], surfactant aggregation [4], prediction of reaction mechanism [5], and investigation of biological membrane models [6, 7]. Techniques other than NMR used to investigate surface properties of biphasic systems include atomic force microscopy [8], scanning electron microscopy [9], nonlinear optics [10], scanning electrochemical microscopy (SECM) [11], and x-ray [12] and neutron [13] scattering.…”

“…Techniques other than NMR used to investigate surface properties of biphasic systems include atomic force microscopy [8], scanning electron microscopy [9], nonlinear optics [10], scanning electrochemical microscopy (SECM) [11], and x-ray [12] and neutron [13] scattering. A number of methods have been proposed for generating slice-resolved spectra of biphasic systems prepared in conventional NMR tubes, and run in high resolution liquid probes equipped with z-gradients [3, 14–16]. Here we study consequences of, and remedies for, magnetic field in homogeneity caused by susceptibility mismatch at the interface.…”

“…One is whether slice volumes are large enough to provide adequate signals from lower-concentration-surface-active species [17]. A second is that it can be difficult to isolate diffusive transport from unanticipated slow convection [16, 18], and slice-selection studies [3] have yet to take this into account. A third problem, which we address here, is line shape distortion in the vicinity of the interface caused by susceptibility mismatch between phases.…”