The development and in vitro evaluation of acrylic strips and dialysis tubing for local drug delivery.

This study reports on the development of drug containing acrylic strips for delivering antimicrobial agents and compares the in vitro release pattern with dialysis tubing. Polyethylmethacrylic strips of suitable dimensions containing 10 to 50% chlorhexidine acetate, 40% metronidazole and 40% tetracycline were prepared. Daily release of the incorporated drugs into 1 ml aliquots was measured spectrophotometrically over a 14 day period. Similarly the release of chlorhexidine gluconate from various lengths of patent and heat sealed dialysis tubing was recorded for 4 days. At 30%, 40% and 50% admixtures the acrylic strips released chlorhexidine up to the 14 day period and a parallel bioassay confirmed the maintenance of antibacterial activity to this time. At the same admixture the release of metronidazole was greater than chlorhexidine and tetracycline. All drugs were released at high levels on day 1 followed by a marked fall in release by day 2 and progressive fall thereafter. The release from tubing was almost total within 24 hours and was independent of sealing the ends. The strips appear to have potential for prolonged drug delivery to periodontal pockets. Preliminary clinical use revealed no patient acceptability problems and alterations in subgingival flora were produced.