CLINICAL PHARMACOLOGY
Systemic Absorption
Absorption studies in humans with the ciprofloxacin
ointment have not been conducted, however, based on studies with ciprofloxacin
solution, 0.3%, mean maximal concentrations are expected to be less than 2.5
ng/mL.
Microbiology
Ciprofloxacin has in vitro activity against a wide range
of gram-negative and gram-positive organisms. The bactericidal action of
ciprofloxacin results from interference with the enzyme DNA gyrase which is
needed for the synthesis of bacterial DNA.
Ciprofloxacin has been shown to be active against most
strains of the following microorganisms both in vitro and in clinical
infections (See INDICATIONS AND USAGE section).
Aerobic Gram-positive Microorganisms
Staphylococcus aureus (methicillin-susceptible
strains)
Staphylococcus epidermidis (methicillin-susceptible
strains)
Streptococcus pneumoniae
Streptococcus Viridans Group
Aerobic Gram-positive Microorganisms
Haemophilus influenzae
The following in vitro data are available; but their
clinical significance in ophthalmologic infections is unknown. The
safety and effectiveness of ciprofloxacin in treating conjunctivitis due to
these microorganisms have not been established in adequate and well controlled
trials.
The following organisms are considered susceptible when
evaluated using systemic breakpoints. However, a correlation between the in
vitro systemic breakpoint and ophthalmological efficacy has not been
established. Ciprofloxacin exhibits in vitro minimal inhibitory concentrations
(MIC's) of 1 mcg/mL or less (systemic susceptible breakpoint) against most
( ≥ 90%) strains of the following ocular pathogens.
Aerobic Gram-positive Microorganisms
Bacillus species
Corynebacterium species
Staphylococcus haemolyticus
Staphylococcus hominis
Aerobic Gram-positive Microorganisms
Acinetobacter calcoaceticus
Enterobacter aerogenes
Escherichia coli
Haemophilus parainfluenzae
Klebsielle pneumoniae
Moraxella catarrhalis
Neisseria gonorrhoeae
Proteus mirabilis
Pseudomonas aeruginosa
Serratia marcesens
Most strains of Burkholderia cepacia and some strains of Stenotrophomonas
maltophilia are resistant to ciprofloxacin as are most anaerobic bacteria,
including Bacteroides fragilis and Clostridium difficile.
The minimal bactericidal concentration (MBC) generally
does not exceed the minimal inhibitory concentration (MIC) by more than a
factor of 2. Resistance to ciprofloxacin in vitro usually develops slowly
(multiple-step mutation). Ciprofloxacin does not cross-react with other
antimicrobial agents such as beta-lactams or aminoglycosides; therefore,
organisms resistant to these drugs may be susceptible to ciprofloxacin.
Organisms resistant to ciprofloxacin may be susceptible to beta-lactams or
aminoglycosides.
Clinical Studies
In multicenter clinical trials, approximately 75% of the
patients with signs and symptoms of bacterial conjunctivitis and positive
conjunctival cultures were clinically cured and approximately 80% had presumed
pathogens eradicated by the end of treatment (day 7).
Animal Pharmacology
Ciprofloxacin and related drugs have been shown to cause
arthropathy in immature animals of most species tested following oral
administration. However, a one month topical ocular study using immature Beagle
dogs did not demonstrate any articular lesions.