title: PAMAM dendrimers for the delivery of the antibacterial Triclosan.
abstract: Many oral care products incorporate an antibacterial compound to prevent the formation of dental plaque which predisposes teeth to dental caries or periodontal disease. Triclosan (TCN) is a commonly used antiplaque agent in toothpastes. Strategies to increase the delivery efficiency of antibacterials using formulation aids such as polyamidoamine (PAMAM) dendrimers are of interest. Solubilisation studies over the pH range 5-12 demonstrated an increase in the level of TCN solubilised with increasing dendrimer concentration (1 mM-5 mM). However, the dendrimer was unable to enhance TCN solubility at lower pH values and the solubilising effect observed was attributed to the ionization of TCN (pKa 8.14) resulting from dendrimer induced pH changes. End group modification of G3 PAMAM dendrimer with phenylalanine in order to promote solubility through pi-pi stacking between TCN and the amino acid has been carried out. Phenylalanine:G3 PAMAM conjugates of different ratios (32:1, 21:1, 16:1) were synthesized. The fully conjugated dendrimer (32:1) had poor aqueous solubility, whereas the 21:1 and 16:1 dendrimer conjugates were water soluble. The 21:1 conjugate was tested for its ability to solubilise TCN, however, again there was no increase over control buffer solutions of the same pH. An alternative approach under investigation is to directly conjugate TCN to PAMAM dendrimers via a hydrolysable linkage.
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gardiner
authors.forename: Sally
authors.initials: S
authors.lastname: Freeman
authors.forename: Matthew
authors.initials: M
authors.lastname: Leach
authors.forename: Alison
authors.initials: A
authors.lastname: Green
authors.forename: Jacqui
authors.initials: J
authors.lastname: Alcock
authors.forename: Antony
authors.initials: A
authors.lastname: D'Emanuele
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D050091:Dendrimers / Q000737:chemistry* / Q000627:therapeutic use; D004337:Drug Carriers / Q000737:chemistry*; D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D010649:Phenylalanine / Q000737:chemistry; D011073:Polyamines / Q000737:chemistry* / Q000627:therapeutic use; D012995:Solubility; D013329:Structure-Activity Relationship; D014260:Triclosan / Q000008:administration & dosage*
chemical_list: D000900:Anti-Bacterial Agents; D050091:Dendrimers; D004337:Drug Carriers; C104700:PAMAM Starburst; D011073:Polyamines; D010649:Phenylalanine; D014260:Triclosan