Comparative analysis of tetracycline-containing dental gels: Poloxamer- and monoglyceride-based formulations

The aim of the paper was to develop tetracycline-containing formulations for the treatment of periodontitis by direct periodontal intrapocket administration. Two different semi-solid formulations were prepared, based on poly(oxyethylene)poly(oxypropylene) block copolymer (poloxamer) and monoglycerides, respectively. Both formulations possess interesting properties as delivery systems. They are easily administered by syringe equipped with needles appropriate for intrapocket delivery, they are characterized by a sol-gel transition, becoming semi-solid once in the periodontal pocket and, finally, they represent biocompatible formulations eliminated from the body by normal routes. A rheological characterization of both formulations was performed in the presence or in the absence of tetracycline, determining the sol-gel transition temperature (T-c) by 'time cure tests' and the z coefficient by 'frequency sweep test'. In addition, the in vitro tetracycline release from formulations was determined. Comparative in vivo studies were conducted, in order (a) to compare the persistence of the gels on the gum and (b) to evaluate the clinical performances of the gels. These latest studies indicated that both poloxamer and monoglycerides gels, when applied subgingivally, produce a significantly improved outcome in moderate to deep periodontal pockets.