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Polymyxin B Sulfate
Polymyxin B sulfate is one of a group of basic polypeptide antibiotics derived from B. polymyxa (B. aerosporus). Sterile Polymyxin B sulfate is in powder form suitable for preparation of sterile solutions for intramuscular, intravenous drip, intrathecal, or ophthalmic use. In the medical literature, dosages have frequently been given in terms of equivalent weights of pure polymyxin B base. Each milligram of pure polymyxin B base is equivalent to 10,000 units of polymyxin B, and each microgram of pure polymyxin B base is equivalent to 10 units of polymyxin B. Aqueous solution of polymyxin B sulfate may be stored up to 12 months
without significant loss of potency if kept under refrigeration. In
the Interest of Safety, Solutions for Parenteral Use Should Be Stored
Under Refrigeration and Any Unused Portion Should Be Discarded After 72
Hours. Polymyxin B sulfate should not be stored in alkaline solutions
since they are less stable.
Actions Polymyxin B sulfate has a bactericidal action against almost all gram-negative bacilli except the Proteus group. Polymyxins increase the permeability of bacterial cell membranes. All gram-positive bacteria, fungi, and the gram-negative cocci, N. gonorrhea and N. menigitidis, are resistant. Susceptibility plate testing: If the Kirby-Bauer method of disc susceptibility testing is used, a 300 unit polymyxin B disc should give a zone of over 11 mm when tested against a polymyxin B-susceptible bacterial strain. Polymyxin B sulfate is not absorbed from the normal alimentary tract.
Since the drug loses 50 percent of its activity in the presence of serum,
active blood levels are low. Repeated injections may give a cumulative
effect. Levels tend to be higher in infants and children. The drug is
excreted slowly by the kidneys. Tissue diffusion is poor and the drug
does not pass the blood brain barrier into the cerebrospinal fluid. In
therapeutic dosage, polymyxin B sulfate causes some nephrotoxicity with
tubule damage to a slight degree.
Acute Infections Caused by Susceptible Strains of Pseudomonas aeruginosa: Polymyxin B sulfate is a drug of choice in the treatment of infections of the urinary tract, meninges, and blood stream, caused by susceptible strains of Ps. aeruginosa. It may also be used topically and subconjunctivally in the treatment of infections of the eye caused by susceptible strains of Ps. aeruginosa. It may be indicated in serious infections caused by susceptible strains of the following organisms, when less potentially toxic drugs are ineffective or contraindicated. NOTE: IN MENINGEAL INFECTIONS, POLYMYXIN B SULFATE SHOULD BE ADMINISTERED ONLY BY THE INTRATHECAL ROUTE.
Intravenous Dissolve 500,000 units polymyxin B sulfate in 300 to 500 mL of 5% dextrose in water for continuous intravenous drip. Adults and Children: 15,000 to 25,000 units/ kg body weight/ day in individuals with normal kidney function. This amount should be reduced from 15,000 units/ kg downward for individuals with kidney impairment. Infusions may be given every 12 hours; however, the total daily dose must not exceed 25,000 units/ kg/ day. Infants: Infants with normal kidney function may receive up to 40,000 units/ kg/ day without adverse effects. Intramuscular Not recommended routinely because of severe pain at injection sites, particularly in infants and children. Dissolve 500, 000 units polymyxin B sulfate in 2 mL sterile distilled water (Sterile Water for Injection, USP) or sterile physiologic saline (Sodium Chloride Injection, USP) or 1% procaine hydrochloride solution. Adults and Children: 25,000 to 30,000 units/ kg/ day. This should be reduced in the presence of renal impairment. The dosage may be divided and given at either 4 or 6 hour intervals. Infants: Infants with normal kidney function may receive up to 40,000 units/ kg/ day without adverse effects. Note: Doses as high as 45,000 units/ kg/ day have been used in limited clinical studies in treating prematures and newborn infants for sepsis caused by Ps. aeruginosa. Intrathecal A treatment of choice for Ps. aeruginosa meningitis. Dissolve 500,000 units polymyxin B sulfate in 10 mL of sterile physiologic saline (Sodium Chloride Injection, USP) for 50,000 units per mL dosage unit. Adults and Children Over 2 Years of Age: Dosage is 50,000 units once daily intrathecally for 3 to 4 days, then 50,000 units once every other day for at least 2 weeks after cultures of the cerebrospinal fluid are negative and sugar content has returned to normal. Children Under 2 Years of Age: 20,000 units once daily, intrathecally for 3 to 4 days or 25,000 units once every other day. Continue with a dose of 25,000 units once every other day for at least 2 weeks after cultures of cerebrospinal fluid are negative and sugar content has returned to normal. IN THE INTEREST OF SAFETY, SOLUTIONS FOR PARENTERAL USE SHOULD BE STORED UNDER REFRIGERATION AND ANY UNUSED PORTION SHOULD BE DISCARDED AFTER 72 HOURS. HOW SUPPLIED Polymyxin B Sulfate Sterile is supplied in 10 mL vials containing 500,000 units (NDC 55390-139-01). Rx ONLY
See BOXED WARNING. Nephrotoxic reactions: Neurotoxic reactions: Facial flushing Other reactions occasionally reported:
No information provided.
See BOXED WARNING.
See BOXED WARNING. Baseline renal function should be done prior to therapy, with frequent monitoring of renal function and blood levels of the drug during parenteral therapy. Avoid concurrent use of a curariform muscle relaxant and other neurotoxic
drugs (ether, tubocurarine, succinylcholine, gallamine, decamethonium,
and sodium citrate) which may precipitate respiratory depression. If signs
of respiratory paralysis appear, respiration should be assisted as required,
and the drug discontinued. As with other antibiotics, use of this drug
may result in overgrowth of nonsusceptible organisms, including fungi.
If superinfection occurs, appropriate therapy should be instituted.
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