Neomycin and Polymyxin B Sulfates and Gramicidin Ophthalmic (Neomycin Sulfate / Polymyxin B Sulfate / Gramicidin Ophthalmic) - Description and Clinical Pharmacology

DESCRIPTION

Neomycin and Polymyxin B Sulfates and Gramicidin Ophthalmic Solution USP is a sterile antimicrobial solution for ophthalmic use.

EACH mL CONTAINS: ACTIVES: Neomycin Sulfate, (equivalent to 1.75 mg neomycin base), Polymyxin B Sulfate equal to 10,000 Polymyxin B units, Gramicidin, 0.025 mg; INACTIVES: Sodium Chloride, Alcohol (0.5%), Poloxamer 188, Propylene Glycol, Purified Water. Hydrochloric Acid and/ or Ammonium Hydroxide may be added to adjust pH (4.7- 6.0).

PRESERVATIVE ADDED: Thimerosal 0.001%.

Neomycin Sulfate is the sulfate salt of neomycin B and C, which are produced by the growth of Streptomyces fradiae Waksman (Fam. Streptomycetaceae). It has a potency equivalent of not less than 600 micrograms of neomycin base per milligram, calculated on an anhydrous basis.

The structural formulae are:

Polymyxin B Sulfate is the sulfate salt of polymyxin B_l and B₂ which are produced by the growth of Bacillus polymyxa (Prazmowski) Migula (Fam. Bacillaceae). It has a potency of not less than 6,000 polymyxin B units per milligram, calculated on an anhydrous basis. The structural formulae are:

Gramicidin (also called gramicidin D) is a mixture of three pairs of antibacterial substances (Gramicidin A, B and C) produced by the growth of Bacillus brevis Dubos (Fam. Bacillaceae). It has a potency of not less than 900 mcg of standard gramicidin per mg. The structural formulae are:

CLINICAL PHARMACOLOGY

A wide range of antibacterial action is provided by the overlapping spectra of neomycin, polymyxin B sulfate, and gramicidin.

Neomycin is bactericidal for many gram-positive and gram-negative organisms. It is an aminoglycoside antibiotic which inhibits protein synthesis by binding with ribosomal RNA and causing misreading of the bacterial genetic code.

Polymyxin B is bactericidal for a variety of gram-negative organisms. It increases the permeability of the bacterial cell membrane by interacting with the phospholipid components of the membrane.

Gramicidin is bactericidal for a variety of gram-positive organisms. It increases the permeability of the bacterial cell membrane to inorganic cations by forming a network of channels through the normal lipid bilayer of the membrane.

Microbiology: Neomycin sulfate, polymyxin B sulfate and gramicidin together are considered active against the following microorganisms:

Staphylococcus aureus, streptococci, including Streptococcus pneumoniae, Escherichia coli, Haemophilus influenzae, Klebsiella-Enterobacter species, Neisseria species and Pseudomonas aeruginosa. The product does not provide adequate coverage against Serratia marcescens.