Solid effervescent formulations as new approach for topical minoxidil delivery

Abstract

Currently marketed minoxidil formulations present inconveniences that range from a grease hard aspect they leave on the hair to more serious adverse reactions as scalp dryness and irritation. In this paper we propose a novel approach for minoxidil sulphate (MXS) delivery based on a solid effervescent formulation. The aim was to investigate whether the particle mechanical movement triggered by effervescence would lead to higher follicle accumulation. Preformulation studies using thermal, spectroscopic and morphological analysis demonstrated the compatibility between effervescent salts and the drug. The effervescent formulation demonstrated a 2.7-fold increase on MXS accumulation into hair follicles casts compared to the MXS solution (22.0±9.7μg/cm² versus 8.3±4.0μg/cm²) and a significant drug increase (around 4-fold) in remaining skin (97.1±29.2μg/cm²) compared to the drug solution (23.5±6.1μg/cm²). The effervescent formulations demonstrated a prominent increase of drug permeation highly dependent on the effervescent mixture concentration in the formulation, confirming the hypothesis of effervescent reaction favoring drug penetration. Clinically, therapy effectiveness could be improved, increasing the administration interval, hence, patient compliance. More studies to investigate the follicular targeting potential and safety of new formulations are needed.

Keywords: Effervescent formulations; Hair follicles; Minoxidil; Preformulation; Skin permeation.