Purpose: The purpose of the research study was to formulate and prepare a medicated chewing gum for the treatment of oral candidiasis as well evaluate the in-vitro release of the essential oils included in the formulation.
Methods: Minimum inhibitory concentration (MIC) test; manufacturing of the medicated chewing gum by direct compression; In-vitro drug release test.
Results: The antifungal activities of the EO’s were determined for C. albicans ATCC 10231 using the microdilution method described by Eloff (1998: 711-713). The MIC values were investigated and determined from highest concentration of 8 mg/ml to lowest of 0.0625 mg/ml. Generally, results obtained (Figure 3) showed that most of the oils exhibit their activities at a concentration of 1 mg/ml except for thyme oil which exhibited a MIC value of 0.5 mg/ml. Spearmint oil had the highest concentration of 4 mg/ml. No activities for all the oils were observed at a concentration above 4 mg/ml.
Further MIC tests were performed to investigate the effectiveness of Eos in combinations. Thyme and lemongrass oils were tested because of their better activities against C. albicans than the other oils; nevertheless peppermint oil as well was further investigated because of its common use as a flavouring agent in chewing gums in order to improve the flavour (Heema & Stuti, 2011: 68; Pagare et al., 2012: 46). The combination of lemongrass and peppermint was shown to be the most suitable due to the fact they have good taste and smell and displayed a MIC value of 0.5 mg/ml. The combination of lemongrass and peppermint oils at ratio 1:1 respectively was therefore selected as the actives pharmaceutical ingredients to be formulated into a MCG.
MCG’s containing lemongrass oil and peppermint oil as active ingredients were prepared by direct compression. No granulation process was required as the gum base ‘’ Health in Gum® ’’(Cafosa, Barcelona, Spain) is a directly compressible powder. Stevia was used as sweetener; silicon dioxide and magnesium stearate were respectively used as glidant and lubricant; No flavour was required due to the excellent organoleptic properties (taste and smell) of the oils. Flexicoat red powder was used as the film coating agent.
Figure 3: Minimum inhibitory concentration values of seven antifungal essential oils. Talc was added in the formulation to overcome the sticking effect which can lead to the damage of the tablet press, knowing that sticking is a frequent problem during compression due to the adhesive nature of the gum base (Maggi et al., 2005:488). The finished product was evaluated general appearance, key dimensions and dissolution profile. No cracks or defects were observed on the gums. The texture and the feel of the finished uncoated gum were also good.
Table 2 summarizes the final product formulation. The gum powder mixes were directly compressed using a conventional rotary tablet press.
Table 2: Directly compressible MCG formulation
Ingredient Function Percentage (w/w)
Health in gum Gum base 91.5
Lemongrass oil API 2
Peppermint oil API 2
Stevia Sweetener 0.5
Magnesium stearate Lubricant 1.5
Silicon dioxide Glidant 1
Talc Anti-adherent 1.5
API- Active Pharmaceutical Ingredient
Conclusion: Essential oils, namely lemongrass and peppermint, were proven to be suitable alternative drugs for the treatment of oral candidiasis displaying antimicrobial activity on C. albicans at lower concentrations. Their inclusion in MCG formulation was made possible by the use of direct compression as the manufacturing method in a pharmaceutical facility in GMP requirements. The release of EO’s from the gums can be studied by the chewing dissolution tester developed by Wennergren. Dissolution studies revealed the fast release of the drugs from the gums at high percentages. The addition of 4% BSA in the dissolution medium helped improved the aqueous solubility. The release profiles of the drugs during dissolution studies after different chewing times are the evidence of efficiency of MCG as drug delivery system.