Bioequivalence of locally acting lozenges: Evaluation of criticalin vivoparameters and first steps towards a bio-predictivein vitrotest method
Locally-acting lozenges are among the most common types of solid dosage forms applied in the oral cavity. Since no guidance on the in vitro demonstration of local bioequivalence is available, we wanted to develop a new bio-predictive test method for dissolution of lozenges based on a set of physiological parameters relevant to lozenge dissolution in the oral cavity. An in vivo sucking study determining the impact of different lozenge (candy) bases and flavours on sucking times, saliva osmolality and salivary flow rates was performed in 6 volunteers. In vivo sucking times were compared with in vitro dissolution times observed in experiments with official dissolution methods. In vitro dissolution times of all formulations were significantly longer than average in vivo sucking times (20–30 vs. <5 min) indicating that official test methods are not applicable for predicting in vivo dissolution of lozenges. Therefore, we developed and evaluated a novel test apparatus enabling the simulation of forces applied by tongue and hard palate during sucking. Results obtained in a first set of in vitro experiments came very close to those obtained in vivo. This novel in vitro approach is thus very promising in terms of predicting the bioequivalence of locally-acting lozenges.