Effectiveness of a Topical Formulation Containing Metronidazole for Wound Odor and Exudate Control

Cathy Kalinski, RN, BSN, CWCN, COCN; Mary Schnepf, RNC, MPH, ET; Debbie Laboy, RPh; Lucy Hernandez, MS, APRN, BC; Jeanne Nusbaum, RN; Brian McGrinder, RPh; Christopher Comfort, MD; Oscar M. Alvarez, PhD


Wounds. 2005;17(4):84-90. 

In This Article


The Calvary Hospital Pharmacy formulated metronidazole 0.75% gel as follows: 3.6g of metronidazole USP (Gallipot Inc., St Paul, Minn) were blended with 10mL of propylene glycol (Paddock Labs, Minneapolis, Minn) to produce a gelatin. Upon dispersion, 480mL of hydroxypropyl methylcellulose (Liqua-GelTM, Paddock Labs) was added and slowly blended until the metronidazole powder dissolved. The metronidazole 0.75% gel was packaged in either 2 or 4oz jars and labeled.

The study was a prospective, single-center, open (uncontrolled) trial. 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.

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 (AdapticTM, 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-.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.

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.

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).