Polymyxin B Sulfate and Trimethoprim Ophthalmic Solution USP* 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. Trimethoprim sulfate, a white, odorless, crystalline powder, is represented by the following structural formula:
Mol. Wt. 678.72
Chemical Name: Trimethoprim sulfate, 2,4-diamino-5-(3,4 5-trimethoxybenzyl)pyrimidine sulfate (2:1)
Polymyxin B sulfate is the sulfate salt of polymyxin B1 and B2 which are produced by the growth of Bacilluspolymyxa (Prazmowski) Migula (Fam. Bacillaceae) . It has a potency of not less than 6,000 polymyxin B units per mg, calculated on an anhydrous basis. The structural formula is:
Each mL Contains: ACTIVES: Polymyxin B Sulfate equal to 10,000 polymyxin B units, Trimethoprim Sulfate (equivalent to trimethoprim 1 mg); INACTIVES: Sodium Chloride, Purified Water. Sulfuric acid and, if necessary, sodium hydroxide may be added to adjust pH (4.0 – 6.2). PRESERVATIVE ADDED: Benzalkonium Chloride 0.004%.
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 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 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.
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 μg/mL trimethoprim and 1 unit/mL polymyxin B.
In vitro studies have demonstrated that the anti-infective components of trimethoprim sulfate 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 (indolepositive), Enterobacter aerogenes, and Serratia marcescens.
Polymyxin B: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes and Haemophilus influenzae.
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 Pseudomonasaeruginosa.**
**Efficacy for this organism in this organ system was studied in fewer than 10 infections.
Polymyxin B sulfate and trimethoprim ophthalmic solution is contraindicated in patients with known hypersensitivity to any of its components.
NOT FOR INJECTION INTO THE EYE.
If a sensitivity reaction to polymyxin B sulfate and trimethoprim ophthalmic solution occurs, discontinue use.
Polymyxin B sulfate and trimethoprim ophthalmic solution is not indicated for the prophylaxis or treatment of ophthalmia neonatorum.
As with other antimicrobial preparations, prolonged use may result in overgrowth of nonsusceptible organisms, including fungi. If superinfection occurs, appropriate therapy should be initiated.
Avoid contaminating the applicator tip with material from the eye, fingers, or other source. This precaution is necessary if the sterility of the drops is to be maintained.
If redness, irritation, swelling or pain persists or increases, discontinue use immediately and contact your physician. Patients should be advised not to wear contact lenses if they have signs and symptoms of ocular bacterial infections.
Carcinogenesis: Long-term studies in animals to evaluate carcinogenic potential have not been conducted with polymyxin B sulfate or trimethoprim.
Mutagenesis: Trimethoprim was demonstrated to be non-mutagenic in the Ames assay. In studies at two laboratories no chromosomal damage was detected in cultured Chinese hamster ovary cells at concentrations approximately 500 times human plasma levels after oral administration; at concentrations approximately 1000 times human plasma levels after oral administration in these same cells, a low level of chromosomal damage was induced at one of the laboratories. Studies to evaluate mutagenic potential have not been conducted with polymyxin B sulfate.
Impairment of Fertility: Polymyxin B sulfate has been reported to impair the motility of equine sperm, but its effects on male or female fertility are unknown.
No adverse effects on fertility or general reproductive performance were observed in rats given trimethoprim in oral dosages as high as 70 mg/kg/day for males and 14 mg/kg/day for females.
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when polymyxin B sulfate and trimethoprim ophthalmic solution is administered to a nursing woman.
Safety and effectiveness in pediatric patients below the age of 2 months have not been established (see WARNINGS).
No overall differences in safety or effectiveness have been observed between elderly and other adult patients.
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.
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.
Polymyxin B Sulfate and Trimethoprim Ophthalmic Solution USP*, containing 10,000 polymyxin B units and 1 mg trimethoprim per mL, is supplied in a plastic bottle with a controlled drop tip in the following size:
10 mL - Prod. No. 31509
DO NOT USE IF IMPRINTED NECKBAND IS NOT INTACT.
Store at 15°-25°C (59°-77°F). PROTECT FROM LIGHT.
*Does not meet USP packaging specification for light resistance.
RETAIN IN CARTON UNTIL TIME OF USE.
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Tampa, Florida 33637
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