Diffusion Techniques: Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure² requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with trovafloxacin mesylate equivalent to 10 mcg trovafloxacin to test the susceptibility of microorganisms to trovafloxacin.

Reports from the laboratory providing results of the standard single-disk susceptibility test with a trovafloxacin mesylate disk (equivalent to 10 mcg trovafloxacin) should be interpreted according to the following criteria:

The following zone diameter interpretive criteria should be used for testing Neisseria gonorrhoeae^c:

Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for trovafloxacin.

As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms that are used to control the technical aspects of the laboratory procedures. For the diffusion technique, the trovafloxacin mesylate equivalent to 10-mcg trovafloxacin disk should provide the following zone diameters in this laboratory quality control strain:

No testing method or interpretive criteria have been established for trovafloxacin against Chlamydia trachomatis.

Azithromycin

No interpretive criteria have been established for testing azithromycin against Neisseria gonorrhoeae. This species is usually not tested against azithromycin.

No testing method or interpretive criteria have been established for azithromycin against Chlamydia trachomatis.

ANIMAL PHARMACOLOGY

Trovafloxacin

Quinolones have been shown to cause arthropathy in immature animals.

Arthropathy and chondrodysplasia were observed in immature animals given trovafloxacin (See WARNINGS).

At doses from 10 to 15 times the human dose based on mg/kg or approximately 3 to 5 times based on mg/m², trovafloxacin has been shown to cause arthropathy in immature rats and dogs. In addition, these drugs are associated with an increased incidence of chondrodysplasia in rats compared to controls. There is no evidence of arthropathies in fully mature rats and dogs at doses from 40 or 10 times the human dose based on mg/kg or approximately 5 times based on mg/m² for a 6-month exposure period.

Unlike some other members of the quinolone class, crystalluria and ocular toxicity were not observed in chronic safety studies with rats or dogs with either trovafloxacin or its prodrug, alatrofloxacin.

Quinolones have been reported to have proconvulsant activity that is exacerbated with concomitant use of non-steroidal antiinflammatory drugs (NSAIDS). Neither trovafloxacin administered orally at 500 mg/kg, nor alatrofloxacin administered intravenously at 75 mg/kg, showed an increase in measures of seizure activity in mice at doses when used in combination with the active metabolite of the NSAIDs fenbufen.

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