The Assessment of Physicochemical and Antimicrobial Properties of Hydrophilic Gels Containing Tetracycline Hydrochloride and Various Concentrations of Ethanol.

The high prevalence of acne, which affects nearly 85% of adolescents and young adults, underscores the importance of exploring new therapeutic solutions. The aim of the present study was to design a stable hydrogel formulation containing tetracycline hydrochloride (TC) in the presence of ethanol at various concentration levels. The antibiotic stability was assessed over a period of 84 days using the HPLC method. The rheological properties of the formulations and their microbiological activity were also evaluated. Hydrogels without ethanol and those containing 5% and 25% alcohol showed similar rheological properties and high stability of the antibiotic throughout the observation period. The formulation with the highest ethanol content of 50% differed significantly from the others in terms of rheological properties. Although the flow and viscosity curves were like those of the other formulations, the viscosity values were significantly lower. The stability of tetracycline in this formulation was also significantly lower, and by the 84th day of observation, the concentration of the drug had decreased to almost 45% of its initial content. The formulations containing the highest concentration of ethanol displayed the highest activity against the biofilm of the acne-causing agent, Cutibacterium acnes. The study demonstrated the possibility of developing stable and antimicrobial effective hydrogel formulations with tetracycline and ethanol as a substance enhancing drug penetration into the hair follicles.

Effect of Hydrogel Substrate Components on the Stability of Tetracycline Hydrochloride and Swelling Activity against Model Skin Sebum.

Due to its high instability and rapid degradation under adverse conditions, tetracycline hydrochloride (TC) can cause difficulties in the development of an effective but stable formulation for the topical treatment of acne. The aim of the following work was to propose a hydrogel formulation that would ensure the stability of the antibiotic contained in it. Additionally, an important property of the prepared formulations was the activity of the alcoholamines contained in them against the components of the model sebum. This feature may help effectively cleanse the hair follicles in the accumulated sebum layer. A series of formulations with varying proportions of anionic polymer and alcoholamine and containing different polymers have been developed. The stability of tetracycline hydrochloride contained in the hydrogels was evaluated for 28 days by HPLC analysis. Formulations containing a large excess of TRIS alcoholamine led to the rapid degradation of TC from an initial concentration of about 10 µg/mL to about 1 µg/mL after 28 days. At the same time, these formulations showed the highest activity against artificial sebum components. Thanks to appropriately selected proportions of the components, it was possible to develop a formulation that assured the stability of tetracycline for ca. one month, while maintaining formulation activity against the components of model sebum.

Evaluation of the Influence of a Hydrogel Containing AMPD on the Stability of Tetracycline Hydrochloride.

Tetracyclines, as beneficial antimicrobial factors in both local and systemic therapy, are characterized by high instability. The aim of the study was the development of the influence of hydrogel formulation on the tetracycline hydrochloride (TC) level under varying storage conditions. The HPLC, XPRD as well as SEM and macroscopic observations were involved in the study. The TC concentration decreased within ca. two months from 9.37 µg/mL to 4.41 µg/mL in the case of the photoprotected TC solution stored at 23 °C, whereas the decrease in storage temperature did not improve the final level of TC. In the presence of AMPD, the TC level in aqueous solution decreased drastically to ca. 1 µg/mL. Application of a polyacrylic acid derivative enabled conservation of the TC level through the ca. two months. Thus, the use of alcoholamine in the preparation of the TC hydrogel may result in the development of a therapeutic product with a dual action against acne, including antimicrobial activity and saponification of free fatty acids deposited in the follicles.

The Influence of Increasing Concentrations of AMPD on the Efficacy of Its Penetration into a Model Skin Sebum Layer.

Alcoholamines are widely used as auxiliary substances in various topical preparations. Their impact on the components of skin sebum allows them to be used in preparations that cleanse the skin of sebum in hair follicles. We measured the effects of various concentrations of aqueous solutions of AMPD (2-amino-2-methyl-1,3-propanediol) on model skin sebum. The volume of reacted sebum was calculated using two methods: optical assessment of the interaction of alcoholamines with the components of model skin sebum and determination of the reacted volume of model skin sebum based on the measurements of changes in the pH of the AMPD solutions. Both methods showed that the most favorable AMPD concentration for model sebum penetration was approximately 1-2%. Lower values of alcoholamine caused premature exhaustion from the solution. Excessively high concentrations resulted in the formation of a dense layer of products hindering effective skin cleansing.