Effect of addition of antimicrobial drugs to human collagen membrane

Antimicrobial agents included in graft material for use in guided tissue regeneration of periodontally diseased tissue may be of value in combating infection, but may also alter the properties of the membrane material and exert an effect upon the host immune response. Metronidazole, niridazole and tinidazole were added to a cross-linked freeze-dried human type I collagen membrane in various doses and the following measured: (i) daily drug release into an aqueous solution, (ii) minimum inhibitory concentration (MIC) of the drugs against periodontopathogens, (iii) the effect of the drugs on mechanical properties of the membrane, and (iv) degradation by bacterial collagenase. In addition, the effects of the drugs on in-vitro cellular response was assessed by measuring blastogenesis of mononuclear cells obtained from patients suffering from periodontal disease and age/sex matched controls following incubation with the periodontopathogen Actinobacillus actinomycetemcomitans (AaY4). It was found that the collagen membranes released high levels of the drugs, at concentrations well above the MIC values. The mechanical properties of the membranes were not affected by the addition of the drugs, although resistance to the collagenases were. The cellular immune response was likewise suppressed in both patient and controls at drug doses comparable with the in-vitro drug release patterns. It is concluded that incorporation of antimicrobial drugs in a collagen barrier membrane may be of value when used in guided tissue regeneration.