New data on the solubility (buffers pH 2.0, pH 5.0, pH 7.4, EtOH (ethanol), OctOH (1-octanol) and IPM (isopropyl myristate)), distribution (OctOH/buffer and IPM/buffer systems), and permeability through the polydimethylsiloxane-polycarbonate membrane (PDS) and PermeaPad barrier (PP) of three structurally similar nitrofuran class drugs: nifurtimox (NFM), nifuratel (NFT) and nifuroxazide (NFX) have been obtained. All the compounds appeared to be very sparingly soluble in the range of physiological pH. In addition, low solubility in organic solvents: EtOH > OctOH > IPM was also determined. The solubility of the studied substances in the organic solvents was shown to be higher than in the aqueous media. The values of the distribution coefficients appeared to be in agreement with the solubility in the respective solvents. According to the distribution in the OctOH/buffer system, only NFX matched the range of optimal lipophilicity (logD=1÷3) for successful absorption. Permeability of all the studied nitrofuran derivatives was shown to be essentially greater through the PP barrier as compared to the PDS membrane. The trends between the distribution coefficients and permeability were disclosed.
