Generic Name

Gentamicin Sulfate, Prednisolone Acetate

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Classification

FDA Approved Indications

• Gentamicin Sulfate: Bacterial infections caused by susceptible organisms.
• Prednisolone Acetate: Inflammatory and allergic ocular conditions, such as conjunctivitis, uveitis, keratitis.

Mechanism of Action

Gentamicin binds to bacterial 30S ribosomal subunit, inhibiting protein synthesis, leading to bacterial cell death. Prednisolone exerts anti-inflammatory effects by suppressing multiple inflammatory mediators and immune responses.

Dosage and Administration

Adult: Gentamicin: Dosing varies based on infection severity and site; typically 3-5 mg/kg/day divided into 2-3 doses. Prednisolone Acetate: Usually one or two drops into affected eye(s) 1-2 times daily, as prescribed.

Pediatric: Gentamicin: Dosing based on weight and infection severity; requires careful monitoring. Prednisolone Acetate: Same as adults, adjusted as needed under supervision.

Geriatric: Gentamicin: Start at lower doses due to possible renal impairment. Prednisolone Acetate: Use with caution, monitor for increased intraocular pressure.

Renal Impairment: Gentamicin: Dose adjustment required; monitor renal function. Prednisolone: Usually no dose adjustment but monitor for increased side effects.

Hepatic Impairment: Prednisolone: Use with caution; monitor for steroid-related side effects.

Pharmacokinetics

Absorption: Gentamicin: Poorly absorbed orally; administered parenterally or topically. Prednisolone: Well absorbed via ocular route; systemic absorption varies.

Distribution: Gentamicin: Mainly in extracellular fluid. Prednisolone: Wide distribution including ocular tissues.

Metabolism: Gentamicin: Not metabolized; excreted unchanged. Prednisolone: Partially metabolized in liver.

Excretion: Gentamicin: Primarily renal excretion. Prednisolone: Renal and hepatic pathways.

Half Life: Gentamicin: ~2-3 hours. Prednisolone: Variable, approximately 2-4 hours systemically, ocular topical forms have different tissue half-lives.

Contraindications

• Gentamicin: Known hypersensitivity to aminoglycosides.
• Prednisolone: Fungal infections, hypersensitivity to corticosteroids.

Precautions

• Gentamicin: Renal impairment, neuromuscular disorders, ototoxicity risk. Prednisolone: Systemic infections, caution in ocular herpes simplex, monitor intraocular pressure, potential corticosteroid side effects with systemic absorption.

Adverse Reactions - Common

• Ototoxicity (hearing loss, tinnitus) (Uncommon with brief use)
• Nephrotoxicity (Uncommon)
• Local ocular irritation, increased intraocular pressure, cataract formation (Common with topical ocular corticosteroids)

Adverse Reactions - Serious

• Allergic reactions including anaphylaxis (Rare)
• Systemic hyperglycemia, secondary infections, osteoporosis (systemic steroids) (Varies)

Drug-Drug Interactions

• Nephrotoxic drugs (e.g., other aminoglycosides, NSAIDs)
• Potassium-sparing diuretics (risk of hyperkalemia)
• Other corticosteroids or immunosuppressants.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Complete full course of antibiotics.
• Report signs of hearing loss, dizziness, or allergic reactions.
• Avoid ocular trauma and follow healthcare provider instructions for eye drops.
• Report any increased eye pain or visual changes.

Special Considerations

Black Box Warnings:

• Gentamicin: Ototoxicity and nephrotoxicity risk, especially with prolonged use.

Genetic Factors: Pharmacogenetic variations may influence drug metabolism and toxicity.

Lab Test Interference: Ongoing renal function and audiology testing recommended during gentamicin therapy.

Overdose Management

Signs/Symptoms: Ototoxicity, nephrotoxicity, hypersensitivity reactions.

Treatment: Discontinue drug, supportive care, hydration, hemodialysis if necessary.

Storage and Handling

Storage: Store at room temperature, protect from light and moisture.

Stability: Stable under recommended storage conditions for shelf life.