BESIVANCE Ophthalmic suspension Ref.[9958] Active ingredients: Besifloxacin

Plasma concentrations of besifloxacin were measured in adult patients with suspected bacterial conjunctivitis who received BESIVANCE bilaterally three times a day (16 doses total). Following the first and last dose, the maximum plasma besifloxacin concentration in each patient was less than 1.3 ng/mL. The mean besifloxacin C_max was 0.37 ng/mL on day 1 and 0.43 ng/mL on day 6. The average elimination half-life of besifloxacin in plasma following multiple dosing was estimated to be 7 hours.

Besifloxacin is an 8-chloro fluoroquinolone with an N-1 cyclopropyl group. The compound has activity against Gram-positive and Gram-negative bacteria due to the inhibition of both bacterial DNA gyrase and topoisomerase IV. DNA gyrase is an essential enzyme required for replication, transcription and repair of bacterial DNA. Topoisomerase IV is an essential enzyme required for partitioning of the chromosomal DNA during bacterial cell division. Besifloxacin is bactericidal with minimum bactericidal concentrations (MBCs) generally within one dilution of the minimum inhibitory concentrations (MICs).

The mechanism of action of fluoroquinolones, including besifloxacin, is different from that of aminoglycoside, macrolide, and β-lactam antibiotics. Therefore, besifloxacin may be active against pathogens that are resistant to these antibiotics and these antibiotics may be active against pathogens that are resistant to besifloxacin. In vitro studies demonstrated cross-resistance between besifloxacin and some fluoroquinolones.

In vitro resistance to besifloxacin develops via multiple-step mutations and occurs at a general frequency of <3.3 × 10^-10 for Staphylococcus aureus and <7 × 10^-10 for Streptococcus pneumoniae.

Besifloxacin has been shown to be active against most isolates of the following bacteria both in vitro and in conjunctival infections treated in clinical trials [see Indications and Usage (1)]:

Aerococcus viridans*
CDC coryneform group G
Corynebacterium pseudodiphtheriticum*
Corynebacterium striatum*
Haemophilus influenzae
Moraxella catarrhalis*
Moraxella lacunata*
Pseudomonas aeruginosa*
Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus hominis*
Staphylococcus lugdunensis*
Staphylococcus warneri*
Streptococcus mitis group
Streptococcus oralis
Streptococcus pneumoniae
Streptococcus salivarius*

* Efficacy for this organism was studied in fewer than 10 infections.

Long-term studies in animals to determine the carcinogenic potential of besifloxacin have not been performed.

No in vitro mutagenic activity of besifloxacin was observed in an Ames test (up to 3.33 mcg/plate) on bacterial tester strains Salmonella typhimurium TA98, TA100, TA1535, TA1537 and Escherichia coli WP2uvrA. However, it was mutagenic in S. typhimurium strain TA102 and E. coli strain WP2 (pKM101). Positive responses in these strains have been observed with other quinolones and are likely related to topoisomerase inhibition.

Besifloxacin induced chromosomal aberrations in CHO cells in vitro and it was positive in an in vivo mouse micronucleus assay at oral doses ≥1,500 mg/kg. Besifloxacin did not induce unscheduled DNA synthesis in hepatocytes cultured from rats given the test compound up to 2,000 mg/kg by the oral route. In a fertility and early embryonic development study in rats, besifloxacin did not impair the fertility of male or female rats at oral doses of up to 500 mg/kg/day. This dose is approximately 26,500 times higher than the mean plasma concentration measured in humans at the recommended human ophthalmic dose.

In a randomized, double-masked, vehicle-controlled, multicenter clinical trial, in which patients 1-98 years of age were dosed 3 times a day for 5 days, BESIVANCE was superior to its vehicle in patients with bacterial conjunctivitis. Clinical resolution was achieved in 45% (90/198) for the BESIVANCE-treated group versus 33% (63/191) for the vehicle-treated group (difference 12%, 95% CI 3%-22%). Microbiological outcomes demonstrated a statistically significant eradication rate for causative pathogens of 91% (181/198) for the BESIVANCE-treated group versus 60% (114/191) for the vehicle-treated group (difference 31%, 95% CI 23%-40%). Microbiologic eradication does not always correlate with clinical outcome in anti-infective trials.