Zymarin

Approved Indications:

• Bacterial Conjunctivitis: Treatment of bacterial conjunctivitis caused by susceptible strains of Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and other ocular pathogens.
• Bacterial Keratitis: Used for infections of the cornea caused by susceptible bacteria.
• Other Ocular Infections: Such as blepharitis and conjunctival infections when caused by susceptible organisms.

Off-label/Clinically Accepted Uses:

• Treatment of systemic bacterial infections (oral/IV formulations) such as respiratory tract infections, urinary tract infections, skin infections, though usage varies by region due to safety concerns.
• Prophylaxis in ocular surgery or invasive eye procedures.

Ophthalmic Formulation:

• Adults and Pediatrics (>1 year):
  Instill 1–2 drops into the affected eye(s) every 2 hours while awake for the first 2 days, then every 4 hours for the next 5 days or as directed by physician.
• Duration: Typically 7 days or as clinically indicated.

Oral Formulation (where available):

• Adults: 400 mg once daily for 5–14 days depending on infection severity and site.
• Elderly: No routine dose adjustment but monitor for adverse effects.
• Renal Impairment: Dose adjustment required in moderate to severe renal dysfunction; reduce dose or extend dosing interval.
• Hepatic Impairment: No specific dose adjustment recommended.

Administration:

• Ophthalmic drops should be applied directly to the conjunctival sac.
• For oral therapy, administer with or without food.
• Complete the full prescribed course even if symptoms improve.

Gatifloxacin is a fluoroquinolone antibiotic that exerts bactericidal effects by inhibiting bacterial DNA gyrase (topoisomerase II) and topoisomerase IV enzymes. These enzymes are essential for bacterial DNA replication, transcription, repair, and recombination. By blocking these enzymes, gatifloxacin prevents bacterial DNA replication and transcription, leading to DNA strand breaks and ultimately bacterial cell death. This dual-target mechanism enhances efficacy against a broad spectrum of Gram-positive and Gram-negative bacteria.

• Absorption: Oral bioavailability approximately 96%; peak plasma concentrations achieved within 1–2 hours after oral administration.
• Distribution: Widely distributed throughout body tissues and fluids; achieves therapeutic levels in respiratory tract, urinary tract, and ocular tissues.
• Metabolism: Minimally metabolized by the liver.
• Elimination: Primarily excreted unchanged via the kidneys (glomerular filtration and tubular secretion); minor biliary excretion.
• Half-life: Approximately 7–9 hours in healthy adults; prolonged in renal impairment.

• Pregnancy: FDA Category C. Animal studies have shown adverse effects on fetal development at high doses; no adequate well-controlled human studies. Use only if benefit justifies risk.
• Lactation: Excreted in breast milk in small amounts; caution advised. Breastfeeding should be avoided or discontinued during treatment.

• Primary Class: Antibiotic
• Subclass: Fluoroquinolone, third-generation

• Known hypersensitivity to gatifloxacin, other fluoroquinolones, or any formulation excipients.
• History of tendon disorders related to fluoroquinolone use.
• Myasthenia gravis (fluoroquinolones may exacerbate muscle weakness).
• Concomitant use with tizanidine (for oral formulation).
• Severe hepatic or renal impairment without appropriate dose adjustment.

• Tendinitis and Tendon Rupture: Increased risk especially in elderly, transplant patients, or concurrent corticosteroid use; discontinue if tendon pain occurs.
• QT Interval Prolongation: Use with caution in patients with known QT prolongation or on QT-prolonging drugs.
• Hypoglycemia and Hyperglycemia: Cases reported; monitor blood glucose in diabetics, especially on oral hypoglycemics or insulin.
• Central Nervous System Effects: May cause dizziness, headache, confusion, or seizures; caution advised in patients with CNS disorders.
• Photosensitivity: Avoid excessive sunlight or UV exposure.
• Resistance Development: Use only for infections proven or strongly suspected to be caused by susceptible bacteria.
• Ophthalmic Use: Avoid contamination of dropper tip; remove contact lenses before use and wait 15 minutes before reinsertion.

Common Adverse Effects:

• Ocular: Eye irritation, burning, stinging, conjunctival hyperemia
• Gastrointestinal (oral): Nausea, diarrhea, abdominal pain
• CNS: Headache, dizziness

Serious and Rare Side Effects:

• Tendon rupture or tendinitis
• Hypersensitivity reactions including rash, pruritus, anaphylaxis
• QT prolongation and arrhythmias
• Severe hypoglycemia or hyperglycemia
• Photosensitivity reactions
• Clostridioides difficile-associated diarrhea (oral use)

Onset: Most ocular side effects occur shortly after instillation; systemic effects depend on administration route and dose.

• Antacids, Sucralfate, Multivitamins, and Minerals: May reduce oral absorption; separate administration by at least 2 hours.
• Warfarin: May potentiate anticoagulant effects; monitor INR.
• Antiarrhythmics and Other QT-prolonging Drugs: Increased risk of arrhythmias.
• Oral Hypoglycemics/Insulin: Risk of hypoglycemia or hyperglycemia.
• Theophylline: Possible increased serum levels and toxicity.
• Tizanidine: Contraindicated due to increased tizanidine levels.
• No significant CYP450 induction or inhibition noted.

• Regulatory agencies have restricted or withdrawn oral gatifloxacin in some markets due to dysglycemia risk; ophthalmic formulations remain widely used.
• Updated warnings emphasize monitoring blood glucose levels in diabetic patients.
• Guidelines recommend avoiding fluoroquinolones for uncomplicated infections to reduce resistance and adverse events.
• Recent recommendations advise caution in elderly and patients with cardiac risks due to QT prolongation.

• Store ophthalmic solutions at 15°C to 25°C (59°F to 77°F).
• Protect from light and excessive heat.
• Keep the bottle tightly closed when not in use.
• Avoid freezing.
• Discard opened ophthalmic solutions according to package instructions, typically after 28 days.
• For oral tablets, store at controlled room temperature 20°C to 25°C, dry place.