Structural and thermal analyses of zinc and lactose in homeopathic triturated systems

A series of different experimental approaches was applied in Zincum metallicum (Zinc met.) samples and lactose controls. Experiments were designed to elucidate the effect of zinc trituration and dynamization on physicochemical properties of homeopathic formulations, using lactose as excipient.

Zinc met. potencies (Zinc met 1-3c) were triturated and dynamized using lactose as excipient, according to Brazilian Homeopathic Pharmacopoeia. Lactose samples (LAC 1-3c) were also prepared following the same protocol and used as controls. The samples were analyzed structurally by Atomic Absorption Spectroscopy (AAS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscopy (SEM), and thermodynamically by Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC).

AAS analysis detected 97.0 % of zinc in the raw material, 0.75 % (Zinc met 1c) and 0.02% (Zinc met 2c). XRD analysis showed that inter-atomic crystalline spacing of lactose was not modified by dynamization. Amorphous and crystalline lactose spheres and particles, respectively, were observed by TEM in all samples, with mean size from 200 to 800 nm. EDX obtained with TEM identified zinc presence throughout the amorphous matter but individualized zinc particles were not observed. SEM images obtained from dynamized samples (LAC 1c and Zinc met 1c) with electron backscattering could not identify zinc metal grains. The dynamization process induced Derivatives of Thermal Gravimetric (DTg) peak modification, which was previously centered near 158°C to lactose, to a range from 140 to 170°C, suggesting the dynamization process modifies the temperature range of water aggregation. Thermal phenomena were analyzed and visualized by Analysis of Variance (ANOVA) and Principal Component Analysis (PCA) statistics. Both indicated that fusion enthalpy of dynamized samples (DynLAC 1-3c; DynZn 1-3c) increased 30.68 J/g in comparison to non-dynamized lactose (LAC; p < 0.05).

Our results suggested no structural changes due to the trituration and dynamization process. However, TG and DSC analyses permit the differentiation of dynamized and non-dynamized groups, suggesting the dynamization process induced a significant increase in the degradation heat. These results call for further calorimetric studies with other homeopathic dilutions and other methodologies, to better understand the dynamics of these systems.