July 23, 2016



The mechanisms by which metronidazole acts in the treatment of rosacea are unknown, but appear to include an anti-inflammatory effect.


Absorption of metronidazole after topical application of MetroLotion® (metronidazole lotion) Topical Lotion is less complete and more prolonged than after oral administration. Detectable plasma levels were found in all subjects following the administration of a 1 gram dose of MetroLotion® Topical Lotion (containing 7.5 mg of metronidazole) applied every morning and evening for 4 days to the faces of 8 patients. The highest concentration (96 ng/mL) seen following the morning dose on Day 5 was approximately 80 times lower than the peak concentrations produced by a single 250 mg tablet of metronidazole. The mean (±SD) AUC0-24 after twice daily administration was 962±373 ng.hr/mL.

Clinical Studies

A controlled clinical study was conducted in 144 patients with moderate to severe rosacea, in which MetroLotion® (metronidazole lotion) Topical Lotion was compared with its vehicle. Applications were made twice daily for 12 weeks during which patients were instructed to avoid spicy foods, thermally hot foods and drinks, alcoholic beverages, and caffeine. Patients were also provided samples of a soapless cleansing lotion and, if requested, a moisturizer. MetroLotion® (metronidazole lotion) Topical Lotion was significantly more effective than its vehicle in mean percent reduction of inflammatory lesions associated with rosacea and in the investigators' global assessment of improvement. The results of the mean percent reduction in inflammatory lesion counts from baseline after 12 weeks of treatment and the investigators' global assessment of improvement at week 12 are presented in the following table:

Efficacy Outcomes at Week 12
Mean Percent Reduction in Inflammatory Lesion Counts from Baseline

MetroLotion® Topical Lotion
Vehicle Lotion
55% 20%
Investigators' Global Assessment of Improvement (percent change from baseline)
  Worse No Change Minimal Improvement Definite Improvement Marked Improvement Clear
MetroLotion® Topical Lotion
5% 12% 11% 32% 32% 8%
Vehicle Lotion
15% 27% 23% 15% 20% 0%

The scale is based on the following definitions:

Worse: Exacerbation of either erythema or quantitative assessment of papules and/or pustules.

No Change: Condition remains the same.

Minimal Improvement: Slight improvement in the quantitative assessment of papules and/or pustules, and/or slight improvement in erythema.

Definite Improvement: More pronounced improvement in the quantitative assessment of papules and/or pustules, and/or more pronounced improvement in erythema.

Marked Improvement: Obvious improvement in the quantitative assessment of papules and/or pustules, and/or obvious improvement in erythema.

Clear: No papules or pustules and minimal residual or no erythema.

Last reviewed on RxList: 9/3/2008
This monograph has been modified to include the generic and brand name in many instances.

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