Effect of cyclodextrins and polymers on triclosan availability and substantivity in toothpastes in vivo

The aqueous solubility of triclosan is only about 10 mu g/ mt. This very lo w solubility can hamper its biological activity in the oral cavity, which c ould explain the mixed clinical results obtained from triclosan toothpaste trials. Triclosan availability in a silica-based toothpaste was improved th rough cyclodextrin solubilization. The triclosan in vivo availability was o ptimized through a series of phase-solubility studies and triclosan release studies. It was found that in toothpastes, natural beta-cyclodextrin (beta CD) was just as good a solubilizer as the more water-soluble beta CD deriv atives. Furthermore, the amount of cyclodextrin could be reduced by as much as 60% through the addition of a small amount of carboxymethylcellulose (C MC), without affecting triclosan release from the toothpaste. Optimally, cy clodextrins resulted in an almost 3-fold enhancement of triclosan availabil ity compared to an identical toothpaste containing no cyclodextrin. In vivo studies in humans showed that replacing triclosan with triclosan/ beta CD in the toothpaste resulted in only moderate improvement in triclosan substa ntivity. However, replacing triclosan with triclosan/beta CD/ CMC complex r esulted in significant improvement in triclosan substantivity. Furthermore, the in vivo studies showed that replacing free triclosan with triclosan/be ta CD/CMC complex resulted in an almost 3-fold increase in initial triclosa n concentration in saliva after brushing and about 2-fold increase in durat ion of activity.