Objective: To evaluate the activity of benzydamine, lidocaine, and bupivacaine, three drugs with
local anesthetic activity, against Candida albicans and non-albicans strains and to clarify their
mechanism of activity.Methods: The minimal inhibitory concentration (MIC) was determined for 20 Candida strains
(18 clinical isolates and two American Type Culture Collection strains). The fungistatic activity
was studied with the fluorescent probe FUN-1 and observation under epifluorescence microscopy
and flow cytometry. The fungicidal activity of the three drugs was assayed by viability counts.
Membrane alterations induced in the yeast cells were evaluated by staining with propidium iodide,
by quantitation of intracellular k+ leakage and by transmission electron microscopy of intact yeast
cells and prepared spheroplasts.Results: The MIC ranged from 12.5–50.0 μg/mL, 5.0–40.0 mg/mL, and 2.5–10.0 mg/mL for
benzydamine, lidocaine, and bupivacaine, respectively. The inhibitory activity of these concentrations
could be detected with the fluorescent probe FUN-1 after incubation for 60 minutes. A very
fast fungicidal activity was shown by 0.2, 50, and 30 mg/mL of benzydamine, lidocaine, and bupivacaine,
respectively.Conclusions: At lower concentrations, the tested drugs have a fungistatic activity, due to yeast
metabolic impairment, while at higher concentrations they are fungicidal, due to direct damage to
the cytoplasmic membrane. Infect. Dis. Obstet. Gynecol. 8:124–137, 2000.
