Incorporation of stingless bee honey in benzoyl peroxide emulgel formulation for acne treatment

Abstract

Acne vulgaris affects people globally with negative psychological impacts. Benzoyl peroxide has widely been used as an effective topical treatment for acne. However, it can cause skin irritation such as drying, itchiness and redness. These side effects may increase the concern among the patients to use benzoyl peroxide as an acne treatment. Hence, this study aimed to formulate a benzoyl peroxide emulgel incorporating stingless bee honey for acne vulgaris treatment. This is because stingless bee honey possesses excellent moisturising properties which are believed can help to counter the side effect of benzoyl peroxide. Besides, stingless bee honey also has antibacterial properties which may enhance the bactericidal (antiacne) effect of benzoyl peroxide. The objectives of this study are to formulate and characterise the physicochemical properties of the benzoyl peroxide and stingless bee honey emulgel formulations, to determine the minimum inhibitory concentration (MIC) with minimum bactericidal concentration (MBC) of the stingless bee honey, to evaluate the in vitro antiacne activity of the formulated emulgel and also to assess the skin hydration, transepidermal water loss (TEWL) and skin erythema of human volunteers after the application of the formulated benzoyl peroxide and stingless bee honey emulgel. Four formulations with the same excipients were prepared which are benzoyl peroxide with stingless bee honey emulgel (F1), benzoyl peroxide emulgel (F2), stingless bee honey emulgel (F3) and base emulgel (F4). All of these formulations underwent characterisation encompassing organoleptic properties, centrifugation, pH, droplet size, polydispersity index (PDI), zeta potential, spreadability, and microbial limit count study. They were further subjected to stability study at two different conditions (30oC/75%RH and 40oC/75%RH) for three months and the formulations’ characterisation was measured in weeks 2, 4 and 12 of the study. Besides, the MIC and MBC of stingless bee honey against P.acnes were evaluated to determine the effective concentration of stingless bee honey to be incorporated into the formulation. Meanwhile, the antiacne study of all formulations was conducted to assess the formulations’ effectiveness against P.acnes bacteria. Lastly, an in vivo study on 26 volunteers was conducted to assess the effectiveness of stingless bee honey in reducing the side effects of benzoyl peroxide and the safety of the formulated emulgel on human skin. All formulations showed good characterisation and were considered stable since all the parameters remained in the acceptable range during the three-month stability study although there were some changes observed for the pH, droplet size, PDI, zeta potential and spreadability study. Based on the MIC and MBC results, it showed that stingless bee honey could inhibit and kill P.acnes bacteria with concentrations of 12.5% and 15% respectively. Hence, a 15% concentration was incorporated into the formulation. Since F3 showed some inhibition zone and the inhibition zone of F1 was significantly larger than F2, hence this proved that stingless bee honey could still exhibit its antiacne effect when in a dosage form. All formulations were able to improve the skin erythema, hydration and TEWL of the volunteers except the F2. F2 worsened these three parameters which were signs of impaired skin barrier. In conclusion, the combination of stingless bee honey with benzoyl peroxide emulgel was successfully developed and effective in reducing the side effects of benzoyl peroxide.