Usage
Gatifloxacin ophthalmic solution is an antibiotic, specifically a fluoroquinolone, indicated for the treatment of bacterial conjunctivitis. It is effective against susceptible strains of various bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Haemophilus influenzae. It works by inhibiting bacterial DNA synthesis, preventing bacterial growth and replication. Please note that the oral and intravenous formulations of gatifloxacin have been removed from the US market due to the risk of serious side effects. This guide refers to the ophthalmic solution, which remains available.
Alternate Names
Gatifloxacin ophthalmic solution is also marketed under brand names such as Zymar® and Zymaxid®.
How It Works
Pharmacodynamics: Gatifloxacin exerts its antibacterial effect by inhibiting DNA gyrase and topoisomerase IV. These enzymes are crucial for bacterial DNA replication, transcription, and repair. By inhibiting these enzymes, gatifloxacin disrupts bacterial DNA synthesis and ultimately leads to bacterial cell death.
Pharmacokinetics: Gatifloxacin ophthalmic solution is administered topically to the eye. Systemic absorption is minimal, minimizing the risk of systemic side effects. The drug primarily exerts its effects locally in the eye tissues. Elimination pathways for the small amount absorbed systemically are primarily renal.
Dosage
Standard Dosage
Adults and Children (≥1 year old):
- Day 1: Instill one drop in the affected eye(s) every 2 hours while awake, up to 8 times.
- Days 2-7: Instill one drop in the affected eye(s) 2 to 4 times a day while awake.
Children (<1 year old):
Use and dose must be determined by a doctor.
Special Cases:
- Elderly Patients: No dosage adjustment is generally required. However, monitoring for potential adverse reactions is recommended due to possible age-related decline in renal function.
- Patients with Renal/Hepatic Impairment: Dose modifications are usually not necessary for ophthalmic use due to minimal systemic absorption. For systemic gatifloxacin (no longer available in the US), dosage adjustments were made based on creatinine clearance for renal impairment and Child-Pugh score for hepatic impairment.
Clinical Use Cases (For Ophthalmic Solution):
The primary clinical use case for gatifloxacin ophthalmic solution is bacterial conjunctivitis. Dosage recommendations are the same as the standard dosage. Gatifloxacin ophthalmic solution is not indicated for use in situations like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments (For Ophthalmic Solution):
Dosage adjustments are generally not required for gatifloxacin ophthalmic solution based on renal/hepatic function, metabolic disorders, or genetic polymorphisms due to its topical application and minimal systemic absorption.
Side Effects
Common Side Effects:
- Eye irritation
- Blurred vision
- Eye pain
- Eye discharge
- Swollen eyelids
- Unpleasant taste
- Headache
Rare but Serious Side Effects:
- Allergic reactions (anaphylaxis, angioedema, dyspnea, urticaria)
- Stevens-Johnson syndrome
- Tendonitis (with systemic use)
Long-Term Effects:
Long-term use of topical antibiotics may lead to fungal or bacterial superinfection.
Adverse Drug Reactions (ADR):
Any signs of allergic reaction, such as itching, hives, difficulty breathing, or swelling of the face, lips, tongue, or throat, should be treated as a medical emergency. Stevens-Johnson syndrome, characterized by fever, sore throat, and a painful red or purplish rash that spreads and blisters, requires immediate medical intervention.
Contraindications
- Hypersensitivity to gatifloxacin, other quinolones, or any component of the formulation.
Drug Interactions
For topical ophthalmic gatifloxacin, no significant drug interactions have been established. However, patients should always inform their doctors about all other medications they are using, including prescription drugs, over-the-counter medications, and supplements.
Pregnancy and Breastfeeding
- Pregnancy: Pregnancy Safety Category C. Use only if the potential benefit justifies the potential risk to the fetus. Animal studies have shown adverse fetal effects at high doses.
- Breastfeeding: It is unknown if gatifloxacin passes into breast milk. Caution should be exercised when administering gatifloxacin to nursing women.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial DNA gyrase and topoisomerase IV.
- Side Effects: Eye irritation, blurred vision, eye pain, allergic reactions.
- Contraindications: Hypersensitivity to gatifloxacin or other quinolones.
- Drug Interactions: No significant interactions established for topical ophthalmic use.
- Pregnancy & Breastfeeding: Category C; use with caution. Excretion in breast milk unknown.
- Dosage: See above for detailed dosing guidelines.
- Monitoring Parameters: Monitor for signs of hypersensitivity reactions and superinfection.
Popular Combinations
No specific popular drug combinations are typically used with gatifloxacin ophthalmic solution.
Precautions
- Patients should avoid wearing contact lenses during treatment with gatifloxacin ophthalmic solution.
- Avoid contaminating the tip of the bottle.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Gatifloxacin ophthalmic solution?
A: For adults and children 1 year and older: Day 1: Instill one drop in the affected eye(s) every 2 hours while awake, up to 8 times. Days 2 through 7: Instill one drop in the affected eye(s) 2 to 4 times a day while awake.
Q2: What are the common side effects of Gatifloxacin ophthalmic solution?
A: Common side effects include eye irritation, blurred vision, eye pain, eye discharge, swollen eyelids, bad taste, and headache.
Q3: Is Gatifloxacin ophthalmic solution safe during pregnancy?
A: Gatifloxacin ophthalmic solution is a Pregnancy Category C drug. It should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.
A: No, patients should not wear contact lenses while using gatifloxacin eye drops or while experiencing symptoms of bacterial conjunctivitis.
Q5: What should I do if I miss a dose of Gatifloxacin ophthalmic solution?
A: Instill the missed dose as soon as you remember, and then return to your regular dosing schedule. Do not instill two drops at the same time to make up for a missed dose.
Q6: How long does it take for Gatifloxacin ophthalmic solution to work?
A: Patients usually start to feel better within a few days, but it’s essential to complete the entire course of treatment as prescribed by the doctor, even if symptoms improve.
Q7: Can Gatifloxacin ophthalmic solution cause allergic reactions?
A: Yes, allergic reactions, including serious ones like anaphylaxis, are possible. Seek immediate medical attention if you experience symptoms such as hives, difficulty breathing, or swelling of the face, lips, tongue, or throat.
Q8: Are there any drug interactions with Gatifloxacin ophthalmic solution?
A: No significant drug interactions have been established for topical ophthalmic gatifloxacin. However, inform your doctor about all other medications you are taking.
Q9: How should I store Gatifloxacin ophthalmic solution?
A: Store at room temperature, away from light and moisture. Do not freeze. Discard any remaining solution after the treatment course is complete.
