Sixteen consecutive consenting patients presenting with malodorous wounds were enrolled for this clinical study (Table 1). All patients received treatment with the topical formulation. Upon initiation and prior to initial application, wounds were assessed for odor, exudate, and signs of infection. Wound odor was evaluated before initial application (baseline Day 0) and once daily by the patient and 1 investigator. A 10cm visual analog scale rating the odor score from 0–10 was used (0=no wound odor, 1–4=mildly offensive, 5–8=moderately offensive, and 9–10 extremely offensive). The patients were followed for 2 weeks. No debridement was undertaken, as it is not usually performed on fungating tumors. Patients on systemic antibiotics, currently receiving chemotherapy or radiotherapy, or with known sensitivity to metronidazole were excluded from the study. All wounds were clinically assessed for general appearance, signs of infection, degree of exudation, skin maceration, wound size (volume), and local pain. Patients were also asked to provide comments about their treatment.
Treatment protocol and dressings. Wounds were cleansed with sterile normal saline before treatment. There were no forceful irrigation techniques and no other cleansing agents utilized. The same dressing technique was used throughout the study. It consisted of a nonadherent primary dressing (Adaptic®, Johnson & Johnson Wound Management, Somerville, NJ) and an absorbent (gauze or nonwoven) secondary dressing. Treatment with metronidazole gel was performed once daily. Using a tongue depressor, enough study medication (about the thickness of a dime, 1–1.5mm) was applied over the entire surface of the wound. If the dressing came off or became soiled, only 1 additional application of the test agent was allowed.
Cost. Costs associated with metronidazole powder and formulation ingredients were compared to the costs of purchasing the commercially available topical formulation. The number of empty jars was counted as an approximation of total amount of product used throughout the study.
Statistical analysis. Summarized odor and exudate scores were evaluated using Winks Basic Edition Statistics Software (TexaSoft, Inc., Cedar Hill, Tex). The mean baseline scores were compared to mean scores following treatment with metronidazole 0.75% gel using a nonparametric test (Friedman’s Test) for the comparison of repeated measures.²⁰ Unlike the parametric repeated measures ANOVA or paired t-test, Friedman’s test does not assume the distribution of the data (eg, normality).

Results

Treatment with metronidazole 0.75% gel was easy and convenient. The application of this topical medication was not associated with any pain or discomfort. The effect of metronidazole 0.75% gel on wound odor is presented in Figures 1 and 2. Figure 1 summarizes the odor scores as determined by the investigator, and Figure 2 presents the scores determined by the patients. There was a statistically significant (p<0.05) decrease in wound odor 24 hours after just 1 (initial) application in both investigator and patient data sets. Statistical significance (p<0.05) was also noted on Days 7 and 14 after the initiation of therapy. Metronidazole 0.75% gel was effective throughout the entire 2-week treatment period. For the most part, there was a close correlation between the investigator and patient odor score. With 2 exceptions (Day 6 and Day 8), the score variation between patient and investigator was <30% (Figure 3). The response to topical metronidazole on wound odor was dramatic with a 100% response rate (10 patients reported complete odor elimination, and 6 reported marked improvement [Figure 4]). Wounds treated with topical metronidazole exhibited less drainage. The decrease in the amount of wound exudate was noticeable after just 2 applications (48 hours) and persisted throughout the study period.