The purpose was to evaluate the ability of MPPT to reduce the time to reaching a clean wound and to achieve wound closure in a pre-clinical wound model. A wound was induced in the rat by administering 1 ml 10% calcium chloride solution into the subcutaneous layer under local anesthesia. Following opening of the abscess, MPPT, a topical antibiotic (24 mg/g gentamicin, L-tryptophan 14 mg/g, zinc sulphate 10 mg/g in a polymethylsiloxane powder ad 1 g), or Control (no treatment) were applied topically to the wound every 24 hours until a clean wound was achieved, i.e. the wound was free from necrosis, pus and fibrinogenous thickenings.
Rats (n=15 per group) receiving MPPT reached the stage of a clean wound in 3.0±0.4 days compared to 7.0±0.4 days for the topical antibiotic and 10.0±0.4 days for Control, corresponding to a 70% reduction in time relative to the control group. Time to wound closure was 13.9±0.3 days for rats receiving MPPT, 18.7±0.6 days for the topical antibiotic, and 23.0±0.4 days for Control, corresponding to a 39% reduction in time relative to the control group.
The surface area of the wounds was measured Day 1 and Day 13. At Day 1, the wound surface areas were similar in all three groups (157.4±8.9 mm2), but at Day 13 the MPPT group had significantly smaller wound areas (5.2±1.7 mm2) compared to the topical antibiotic (38.0±1.5 mm2) and Control groups (95.7±11.3 mm2).
The study was conducted in young rats that were still growing and gaining weight. At the start of the study the average weight was similar in all groups (251±5g), but at Day 19, it was only the rats receiving MPPT that exhibited a weight increase during the study (271±5g). Animals receiving the topical antibiotic did not gain weight (249±5g) and animals in the Control group lost weight (242±16 g).
Evaluations of wound smears taken the first three days after opening of the abscess showed that the level of microbial invasion was reduced in the topical antibiotic group, whereas the MPPT and the Control groups were comparable. This indicates that MPPT lacks any antimicrobial effects, which is in agreement with other findings.
The study found that MPPT reduced the time to reaching a clean wound by 70% relative to the control group. The reduced time to reach a clean wound promoted the overall wound healing process such that the rats receiving MPPT reached full wound closure 40% quicker compared to rats in the control group and 26% quicker than rats receiving topical antibiotic.