How Do Ophthalmic Aminoglycosides Work?

Aminoglycosides are a class of antibiotics, and ophthalmic aminoglycosides are antibiotic solutions and ointments used as topical applications to treat bacterial eye infections. Some of the ophthalmic aminoglycosides are effective for fungal infections.

Aminoglycosides have twofold action against bacterial infections:

• Create fissures in the bacterial cell membrane, which causes the bacterial cellular contents to leak out, and enables the uptake of the antibiotic into the bacterial cell.
• Block bacterial protein synthesis.

Bacteria are broadly classified as gram-positive or gram-negative based on a lab test known as the Gram stain test. Gram stain test uses a violet stain (gentian violet) to find the type of bacteria infecting the tissue that is tested. Gram-positive bacteria absorb and retain the violet stain, while gram-negative bacteria do not retain the color.

Aminoglycosides are potent antibiotics against aerobic gram-negative bacteria. Aerobic bacteria require oxygen for survival, while anaerobic bacteria thrive in low-oxygen environments. Aminoglycosides are more active against aerobic bacteria because they have the energy that is required for the absorption of the antibiotic, while anaerobic bacteria have low energy.

Uses of ophthalmic aminoglycosides include:

Ophthalmic aminoglycosides are used for several types of bacterial and fungal infections. Pseudomonas aeruginosa is one of the most common bacterial infections that affects the eyes. Eye conditions treated with ophthalmic glycosides include:

• Conjunctivitis (inflammation in the whites of the eyes and the inner surface of the eyelids from bacterial infection)
• Eye infections
• Prophylaxis (preventive use) against infection after eye surgery
• Fungal keratitis (inflammation of cornea from fungal infection)
• Fungal conjunctivitis
• Fungal blepharitis (inflammation of the eyelids due to fungal infection)
• Candidiasis (Candida yeast infection)

Side effects of ophthalmic aminoglycosides may include:

• Redness and tearing of the eyes
• Transient irritation, burning or stinging
• Allergic reactions to preservatives such as parabens in the eye drops
• Allergic contact dermatitis
• Erythema multiforme (skin rash from immune reaction)
• Punctate keratitis (inflammation in the cornea)
• Itching and swelling of the eyelids

Names of ophthalmic aminoglycoside drugs include:

• Ophthalmic gentamicin sulfate (Genoptic, Gentak)
• Ophthalmic tobramycin (AKTob, Tobrex)
• Ophthalmic natamycin (Natacyn)