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Abstract: Indomethacin (IM) easily forms an amorphous complex with lidocaine (LC) by heat treatment. To know the mechanism involved in the formation of this complex, we studied temperature-dependent phase changes in mixtures of IM and lidocaine hydrochloride (LH), in which the cationic form of LC forms a salt with Cl−, in various molar ratios by using DSC and NMR. Although heating of the mixture of IM and LC (IM+LC), formed a eutectic mixture, that of IM and LH (IM+LH) did not, and IM in the IM+LH mixture was dissolved into fused LH. Cooling of the fused IM+LH showed the glass transition in all of the samples containing various amounts of IM, suggesting that fused IM+LH took a homogenous amorphous state (IM/LH) below its glass transition temperature, in contrast to the fused IM+LC, which formed the rubber state and/or glass state depending on the molar content of IM. The results of the NMR study showed that IM in IM/LH caused the electronic structure of LH to change in such a way as to become similar to that of LC, but this effect was limited. Hence, mode of interaction of LH with IM is different from that of LC with IM. [Copyright &y& Elsevier]

Abstract: We studied temperature-dependent phase changes in the mixture of indomethacin (IM) and lidocaine (LC) in various molar ratios by differential scanning calorimetry (DSC). DSC studies were carried out between −40°C and 180°C heating/cooling/heating cycle at a rate of 10°C/min under a nitrogen gas flow. Although LC in the liquid state was crystallized, fused IM showed a glass transition signal upon cooling. Hence, cooling of fused IM caused it to assume the amorphous state below its glass transition temperature. Heating of the mixture of IM and LC resulted in formation of a eutectic mixture between them, and cooling of the fused mixture caused formation of the amorphous state at any molar ratio examined. It is noteworthy that the amorphous solid of the fused complex of IM and LC was in the rubber state and glass state in the mixtures containing IM between 20% and 40%, whereas there was only the glass state in the samples containing 50% IM and higher. In addition, crystallization of LC took place by cooling the fused sample containing 10% IM. [Copyright &y& Elsevier]

Abstract: Nanoparticles effectively deliver therapeutic agent by penetrating into the rat skin in vivo. Indomethacin (IM) and coumarin-6 were loaded in PLGA nanoparticles with an average diameter of 100nm. Indomethacin (IM) and coumarin-6 were chosen as a model drug and as a fluorescent marker, respectively. The surfaces of the nanoparticles were negatively charged. Permeability of IM-loaded PLGA nanoparticles through rat skin was studied in vivo. Higher amount of IM was delivered through skin when IM was loaded in nanoparticles than IM was free molecules. Also, iontophoresis was applied to enhance the permeability of nanoparticles. When iontophoresis was applied at 0.05mA/cm2, permeability of IM was much higher than that obtained by simple diffusion of nanoparticles through skin. The combination of charged nanoparticle system with iontophoresis is useful for effective transdermal systemic delivery of therapeutic agents. [Copyright &y& Elsevier]

Abstract: Nanoparticles effectively deliver therapeutic agent by penetrating into the skin. Indomethacin (IM) and coumarin-6 were loaded in PLGA nanoparticles with an average diameter of 100nm. IM and coumarin-6 were chosen as a model drug and as a fluorescent marker, respectively. The surfaces of the nanoparticles were negatively charged. Permeability of IM-loaded PLGA nanoparticles through rat skin was studied. Higher amount of IM was delivered through skin when IM was loaded in nanoparticles than IM was free molecules. Also, iontophoresis was applied to enhance the permeability of nanoparticles. When iontophoresis with 3V/cm was applied, permeability of IM was much higher than that obtained by simple diffusion of nanoparticles through skin. The combination of charged nanoparticle system with iontophoresis is useful for effective transdermal delivery of therapeutic agents. [Copyright &y& Elsevier]