Trimethoprim Sulfate and Polymyxin B Sulfate

INDICATIONS AND USAGE Trimethoprim Sulfate and Polymyxin B Sulfate Ophthalmic Solution is indicated in the treatment of surface ocular bacterial infections, including acute bacterial conjunctivitis, and blepharoconjunctivitis, caused by susceptible strains of the following microorganisms: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus viridans, Haemophilus influenza and Pseudomonas aeruginosa. * *Efficacy for this organism in this organ system was studied in fewer than 10 infections.

DOSAGE AND ADMINISTRATION Adults: In mild to moderate infections, instill one drop in the affected eye(s) every three hours (maximum of 6 doses per day) for a period of 7 to 10 days. Pediatric Use: Clinical studies have shown Trimethoprim and Polymyxin B Sulfate Ophthalmic Solution to be safe and effective for use in pediatric patients over two months of age. The dosage regimen is the same as for adults.

WARNINGS NOT FOR INJECTION INTO THE EYE. If a sensitivity reaction to Trimethoprim and Polymyxin B Sulfate Ophthalmic Solution occurs, discontinue use. Trimethoprim Sulfate and Polymyxin B Sulfate Ophthalmic Solution is not indicated for the prophylaxis or treatment of ophthalmic neonatorum.

CONTRAINDICATIONS Trimethoprim Sulfate and Polymyxin B Sulfate Ophthalmic Solution is contraindicated in patients with known hypersensitivity to any of its components.

ADVERSE REACTIONS The most frequent adverse reaction to Trimethoprim Sulfate and Polymxin B Sulfate Ophthalmic Solution is local irritation consisting of increased redness, burning, stinging, and/or itching. This may occur on instillation, within 48 hours, or at any time with extended use. There are also multiple reports of hypersensitivity reactions consisting of lid edema, itching, increased redness, tearing, and/or circumocular rash. Photosensitivity has been reported in patients taking oral trimethoprim.

CLINICAL PHARMACOLOGY Trimethoprim is a synthetic antibacterial drug active against a wide variety of aerobic gram-positive and gram-negative ophthalmic pathogens. Trimethoprim blocks the production of tetrahydrofolic acid from dihydrofolic acid by binding to and reversibly inhibiting the enzyme dihydrofolate reductase. This binding is very much stronger for the bacterial enzyme than for the corresponding mammalian enzyme. For that reason, trimethoprim selectively interferes with bacterial biosynthesis of nucleic acids and proteins. Polymyxin B, a cyclic lipopeptide antibiotic, is rapidly bactericidal for a variety of gram-negative organisms, especially Pseudomonas aeruginosa . It increases the permeability of the bacterial cell membrane by interacting with the phospholipid components of the membrane. When used topically, trimethoprim and polymyxin B absorption through intact skin and mucous membranes is insignificant. Blood samples were obtained from 11 human volunteers at 20 minutes, 1 hour and 3 hours following instillation in the eye of 2 drops of ophthalmic solution containing 1 mg trimethoprim and 10,000 units polymyxin B per mL. Peak serum concentrations were approximately 0.03 mcg/mL trimethoprim and 1 unit/mL polymyxin B. Microbiology: In vitro studies have demonstrated that the anti-infective components of Trimethoprim and Polymyxin B Sulfate Ophthalmic Solution are active against the following bacterial pathogens that are capable of causing external infections of the eye: Trimethoprim: Staphylococcus aureus and Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus faecalis, Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus aegyptius, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis (indole-negative), Proteus vulgaris (indole-positive), Enterobacter aerogenes, and Serratia marcescens. Polymyxin B: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes and Haemophilus influenzae.