Overview
DESCRIPTION Polymyxin B Sulfate and Trimethoprim Ophthalmic Solution is a sterile antimicrobial solution for topical ophthalmic use. It has a pH of 4.0 to 6.2 and osmolality of 270 to 310 mOsm/kg. Chemical Names: Trimethoprim sulfate, 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine sulfate (2:1), is a white, odorless, crystalline powder with a molecular weight of 678.
Mechanism of Action
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 and therefore 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.
Indications
- INDICATIONS AND USAGE Polymyxin B Sulfate and Trimethoprim 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 influenzae and Pseudomonas aeruginosa. * *Efficacy for this organism in this organ system was studied in fewer than 10 infections.
Common Doses
- Refer to label
Dosage
DOSAGE AND ADMINISTRATION 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.
Contraindications
- CONTRAINDICATIONS Polymyxin B Sulfate and Trimethoprim Ophthalmic Solution is contraindicated in patients with known hypersensitivity to any of its components.
Side Effects
- ADVERSE REACTIONS The most frequent adverse reaction to Polymyxin B Sulfate and Trimethoprim 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.
Interactions
- No major interactions listed on the FDA label. Always consult a healthcare professional.