Abstract
Hydroquinone (HQ) is an anti-hyperpigmentation agent with poor physicochemical stability. HQ formulations are currently elaborated by compounding in local pharmacies. Variability in the characteristics of HQ topical formulations can lead to remarkable differences in terms of their stability, efficacy, and toxicity. Four different semisolid O/W formulations with 5% HQ were prepared using: (i) Beeler´s base plus antioxidants (F1), (ii) Beeler´s base and dimethyl isosorbide (DMI) as solubiliser (F2), (iii) olive oil and DMI (F3), and (iv) Nourivan®, a skin-moisturising and antioxidant base, along with DMI (F4). Amongst the four formulations, F3 showed the greatest physicochemical stability with less tendency to coalescence but with marked chromatic aberrations. An inverse correlation was established by multivariate analysis between the mean droplet size in volume and the steady-state flux, which explains why F3, with the smallest droplet size and the most hydrophobic excipients, exhibited the highest permeation across both types of membranes with enhancement ratios of 2.26 and 5.67-fold across Strat-M® and mouse skin, respectively, compared to F1. It is crucial to understand how the HQ is formulated, bearing in mind that the use of different excipients can tune the transdermal delivery of HQ significantly.
Highlights
Hydroquinone (HQ) ointments and creams are one of the most frequent types of formulations prescribed by dermatologists to treat the hyperpigmentation of the skin [1]
The trend in droplet size expressed in volume, number, or area was the same in all the cases, in which F1 was the formulation with the highest droplet size (61.8 ± 3.4 μm) followed by F2 (44.9 ± 4.5 μm), F4 (26.0 ± 1.9 μm), and F3 (8.3 ± 0.8 μm)
An inverse correlation was established between the mean droplet size in volume and the steadystate flux, which explains why F3 exhibited the shortest lag time and the highest permeation across both types of membranes with enhancement ratios of 2.26 and 5.67-fold across Strat-M® and mouse skin, respectively, compared to F1
Summary
Hydroquinone (HQ) ointments and creams are one of the most frequent types of formulations prescribed by dermatologists to treat the hyperpigmentation of the skin [1]. The poor physicochemical stability of HQ topical formulations is a crucial problem that has led to low interest within the pharmaceutical industry for the manufacturing of HQ topical formulations; patients need to rely on extemporaneously produced products prepared by community pharmacies. The hydrophilic nature of HQ is an extra challenge in developing topical formulations, as its permeability is limited unless an appropriate penetration enhancer is included in the extemporaneous prepared topical products [7,8,9]. Variability in the physicochemical characteristics of different HQ formulations can lead to remarkable differences in terms of its stability, efficacy, and toxicity, and it is an interesting topic of research due to its significant clinical implications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
