Farmacja Polska (Sep 2021)
Development and qualitative assesment of medicinal aerosol with lidocaine hydrochloride based on sodium alginate
Abstract
Medicinal aerosols for external use are a less popular form of the drug than aerosols for internal use, i.e., inhalation aerosols. Most common are dermal and nasal aerosols. If the aerosol is used on damaged skin, it must be sterile. Aerosols intended for use on damaged epidermis form a bandage after spraying, protecting the wound from external contamination. The use of natural polymers such as alginates is also widespread in the treatment of wounds and burns. Alginates gel creates hydrogels with a high degree of hydration. This process happens by adding electrolytes. A moist environment promotes proper wound healing processes. What is more, bandages reduce the risk of wound infection. The aim of this work was to develop the composition and technology of manufacture for an aerosol gel based on the natural polymer such as sodium alginate. The active ingredient used as a topical anesthetic in the formulations was lidocaine hydrochloride in 1% concentration. It is characterized by a local anesthetic effect and is used in creams, ointments, and gels commercially available in pharmacies. After the aerosol is sprayed on the surface, the gel covers it evenly and does not need to be spread. The form of a gel gives a feeling of cooling to the burned area, and lidocaine hydrochloride is designed to anesthetize it additionally. Rheological evaluation of the obtained gels was a performer. Effects of the addition of the active substance and excipients on the viscosity of the formulations were investigated. The efficacy of antimicrobial preservation was assessed to select the preservative. In addition, the amount of propellant and a suitable valve and spray atomizer were also chosen for each aerosol to reduce the foaming effect. Quantitative determination of the active substance present in the aerosol composition was performed using high-performance liquid chromatography (HPLC) with isocratic elution. The method used was validated for specificity, accuracy, precision, and linearity. Based on the calibration curve, limits of detection and quantification (LOD and LOQ) for lidocaine hydrochloride were also calculated. The optimal concentration of sodium alginate in the developed gel is 0.6%, which was confirmed by the viscosity test results. The preservative was bronopol in concentration 0,01%. Isopropanol and colloidal silica were included in the formulation to reduce the foam created after the aerosol was sprayed on the substrate. The amount of propellant in relation to the amount of the gel was around 10:90 (m/m).
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