Besifloxacin was developed in the early 2000s as a fluoroquinolone antibiotic specifically for ophthalmic use. It is used to treat bacterial eye infections, such as conjunctivitis, by killing bacteria or inhibiting their growth. Besifloxacin is available as an eye drop and is often prescribed for short-term treatment of eye infections. It works by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes essential for bacterial DNA replication and survival.
BRAND NAMES
Besivance – a prescription eye drop used to treat bacterial conjunctivitis.
MECHANISM OF ACTION
Besifloxacin works by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes essential for DNA replication, transcription, and repair. This disruption prevents bacteria from multiplying and ultimately leads to their death.
PHARMACOKINETICS
Absorption
Besifloxacin is administered as an ophthalmic (eye drop) solution, and systemic absorption is minimal. Most of the drug stays in the eye, achieving high local concentrations while very little enters the bloodstream, reducing the risk of systemic side effects.
Distribution
Besifloxacin, given as an eye drop, stays mostly in the tear film and cornea, providing high local concentrations to treat eye infections. Systemic absorption is minimal, with less than 1% of the dose entering the bloodstream, so it rarely affects other tissues.
Metabolism
Besifloxacin undergoes minimal metabolism in the body. Most of the drug remains unchanged in the eye, and the small amount that enters systemic circulation is primarily excreted unchanged in the urine, with negligible biotransformation by the liver.
Excretion
Besiloxacin is primarily excreted unchanged in the urine. Since systemic absorption is minimal after ophthalmic use, only a small fraction reaches the kidneys, and most of the drug is eliminated locally from the eye through tears and drainage.
PHARMACODYNAMICS
Besifloxacin is a bactericidal fluoroquinolone that kills bacteria by inhibiting DNA gyrase and topoisomerase IV, enzymes essential for bacterial DNA replication. It is highly effective against the bacteria that commonly cause eye infections, acting directly at the site of infection.
ADMINISTRATION
Besifloxacin is administered as ophthalmic eye drops, usually applied directly to the affected eye several times a day as prescribed.
DOSAGE AND STRENGTH
Besifloxacin is typically available as 0.6% ophthalmic (eye) drops. The usual dosage for bacterial conjunctivitis is one drop in the affected eye every 8 hours for 7 days, or as prescribed by a doctor.
FOOD INTERACTIONS
Besifloxacin eye drops have no significant food interactions, since systemic absorption is minimal. Patients can eat normally while using the medication.
DRUG INTERACTIONS
Besifloxacin has minimal drug interactions due to its low systemic absorption. However, caution is advised if used with other topical ophthalmic medications, as they may affect eye surface exposure or wash out the drops if applied too closely together. It is generally recommended towait at least 5–10 minutes between different eye drops.
CONTRAINDICATIONS
Besifloxacin is contraindicated in individuals who have a known hypersensitivity to besifloxacin, other fluoroquinolones, or any component of the formulation. It should not be used in such patients due to the risk of allergic reactions.
SIDE EFFECTS
Common side effects of besifloxacin eye drops include mild eye irritation, redness, burning,or stinging at the application site. Less frequently, patients may experience blurred vision, itching, or tearing. Serious allergic reactions are rare.
TOXICITY
Besifloxacin has a low toxicity profile when used as ophthalmic drops due to minimal systemic absorption. Overuse or accidental ingestion may cause eye irritation, redness, or gastrointestinal upset, but serious systemic toxicity is extremely rare.
