STORAGE: Store polymyxin B sulfate/trimethoprim between temperatures of 15 C to 25 C (59 F - 77 F).
DOSING: The recommended dosing for polymyxin B sulfate/trimethoprim is to apply 1 drop into the affected eye(s) every 3 hours for 7 to 10 days with a maximum of 6 doses per day.
DRUG CLASS AND MECHANISM: Polymyxin B sulfate/trimethoprim is an antibiotic eye drop composed of two drugs. Polymyxin B sulfate works by altering bacterial cell wall structure that causes the leaking out of cellular contents that can result in cell death. Trimethoprim is an antibiotic that interferes with the production of tetrahydrofolic acid, a chemical that is necessary for bacteria and human cells to produce proteins. Trimethoprim inhibits production of tetrahydrofolic acid by inhibiting the enzyme responsible for making tetrahydrofolic acid from dihydrofolic acid. This inhibition interferes with the ability of bacteria to survive. Polymyxin B sulfate/trimethoprim is effective against gram-positive and gram-negative bacteria such as:
- Staphylococcus aureus and epidermis,
- Streptococcus pyogenes,
- Streptococcus faecalis,
- Streptococcus pneumonia,
- E. coli,
- Haemophilus influenzae,
- Klebsiella pneumoniae,
- and Pseudomonas aeruginosa.
The FDA approved polymyxin B sulphate/trimethoprim in October 1988.
Medically reviewed by Eni Williams, PharmD, PhD
REFERENCE: FDA Prescribing Information.
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