Polymyxin B

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# Black Box Warning

# Overview
Polymyxin B is an anti-bacterial agent that is FDA approved for the treatment of infections of the urinary tract, meninges, and bloodstream and used subconjunctivally in the treatment of infections of the eye caused by susceptible strains of P. aeruginosa. There is a Black Box Warning for this drug as shown here.  Common adverse reactions include facial flushing, dizziness progressing to ataxia, drowsiness, peripheral paresthesias.

# Adult Indications and Dosage

## FDA-Labeled Indications and Dosage (Adult)
- Polymyxin B sulfate is a drug of choice in the treatment of infections of the urinary tract, meninges, and bloodstream caused by susceptible strains of P. aeruginosa.  It may also be used topically and subconjunctivally in the treatment of infections of the eye caused by susceptible strains of P. 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:
- H influenzae, specifically meningeal infections.
- Escherichia coli, specifically urinary tract infections.
- Aerobacter aerogenes, specifically bacteremia.
- Klebsiella pneumoniae, specifically bacteremia.
NOTE:  IN MENINGEAL INFECTIONS, POLYMYXIN B SULFATE SHOULD BE ADMINISTERED ONLY BY THE INTRATHECAL ROUTE
- To reduce the development of drug-resistant bacteria and maintain the effectiveness of polymyxin B and other antibacterial drugs, polymyxin B should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.  When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy.  In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
- Intravenous
- Dissolve 500,000 polymyxin B units in 300 to 500 mL solutions for parenteral dextrose injection 5% for continuous drip.
- 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.
- Intramuscular
- Not recommended routinely because of severe pain at injection sites, particularly in infants and children. Dissolve 500,000 polymyxin B units in 2 mL sterile water for injection or sodium chloride injection or procaine hydrochloride injection 1%.
- 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.
- Intrathecal
- A treatment of choice for P. aeruginosa meningitis.  Dissolve 500,000 polymyxin B units in 10 mL sodium chloride injection, USP for 50,000 units per mL dosage unit.
- 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.
- IN THE INTEREST OF SAFETY, SOLUTIONS OF PARENTERAL USE SHOULD BE STORED UNDER REFRIGERATION, AND ANY UNUSED PORTIONS SHOULD BE DISCARDED AFTER 72 HOURS.
- Topical
- Ophthalmic:  Dissolve 500,000 polymyxin B units in 20 to 50 mL sterile water for injection or sodium chloride injection USP for a 10,000 to 25,000 units per mL concentration.
- For the treatment of P. aeruginosa infections of the eye, a concentration of 0.1 percent to 0.25 percent (10,000 units to 25,000 units per mL) is administered 1 to 3 drops every hour, increasing the intervals as response indicates.
- Subconjunctival injection of up to 100,000 units/day may be used for the treatment of P. aeruginosa infections of the cornea and conjunctiva.
- Note:  Avoid total systemic and ophthalmic instillation over 25,000 units/kg/day.

## Off-Label Use and Dosage (Adult)

### Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Polymyxin B in adult patients.

### NonGuideline-Supported Use
There is limited information regarding Off-Label NonGuideline-Supported Use of Polymyxin B in adult patients.

# Pediatric Indications and Dosage

## FDA-Labeled Indications and Dosage (Pediatric)
- Intravenous
- Dissolve 500,000 polymyxin B units in 300 to 500 mL solutions for parenteral dextrose injection 5% for continuous drip.
- 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 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 polymyxin B units in 2 mL sterile water for injection or sodium chloride injection or procaine hydrochloride injection 1%.
- 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 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 P aeruginosa.
- Intrathecal
- A treatment of choice for P. aeruginosa meningitis.  Dissolve 500,000 polymyxin B units in 10 mL sodium chloride injection, USP for 50,000 units per mL dosage unit.
- 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 the cerebrospinal fluid are negative and sugar content has returned to normal.
- IN THE INTEREST OF SAFETY, SOLUTIONS OF PARENTERAL USE SHOULD BE STORED UNDER REFRIGERATION, AND ANY UNUSED PORTIONS SHOULD BE DISCARDED AFTER 72 HOURS.
- Topical
- Ophthalmic:  Dissolve 500,000 polymyxin B units in 20 to 50 mL sterile water for injection or sodium chloride injection USP for a 10,000 to 25,000 units per mL concentration.
- For the treatment of P. aeruginosa infections of the eye, a concentration of 0.1 percent to 0.25 percent (10,000 units to 25,000 units per mL) is administered 1 to 3 drops every hour, increasing the intervals as response indicates.
- Subconjunctival injection of up to 100,000 units/day may be used for the treatment of P. aeruginosa infections of the cornea and conjunctiva.
- Note:  Avoid total systemic and ophthalmic instillation over 25,000 units/kg/day.

## Off-Label Use and Dosage (Pediatric)

# Contraindications
- This drug is contraindicated in persons with a prior history of hypersensitivity reactions to polymyxins.

# Warnings
- Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including Polymyxin B for Injection, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile. C. difficile produces toxins A and B which contribute to the development of CDAD.Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy.  CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.  If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

### Precautions
- Prescribing polymyxin B in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug resistant bacteria.

# Adverse Reactions

## Clinical Trials Experience
- Albuminuria, cylinduria, azotemia, and rising blood levels without any increase in dosage.
- Facial flushing, dizziness progressing to ataxia, drowsiness, peripheral paresthesias (circumoral and stocking glove), apnea due to concurrent use of curariform muscle relaxants, other neurotoxic drugs or inadvertent overdosage, and signs of meningeal irritation with intrathecal administration, e.g., fever, headache, stiff neck and increased cell count and protein cerebrospinal fluid.
- Other reactions occasionally reported:  Drug fever, urticarial rash, pain (severe) at intramuscular injection sites, and thrombophlebitis at intravenous injection sites.

## Postmarketing Experience
There is limited information regarding Postmarketing Experience of Polymyxin B in the drug label.

# Drug Interactions
- 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.

# Use in Specific Populations

### Pregnancy
Pregnancy Category (FDA): 
THE SAFETY OF THIS DRUG IN HUMAN PREGNANCY HAS NOT BEEN ESTABLISHED.
Pregnancy Category (AUS): 
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Polymyxin B in women who are pregnant.

### Labor and Delivery
There is no FDA guidance on use of Polymyxin B during labor and delivery.

### Nursing Mothers
There is no FDA guidance on the use of Polymyxin B with respect to nursing mothers.

### Pediatric Use
There is no FDA guidance on the use of Polymyxin B with respect to pediatric patients.

### Geriatic Use
There is no FDA guidance on the use of Polymyxin B with respect to geriatric patients.

### Gender
There is no FDA guidance on the use of Polymyxin B with respect to specific gender populations.

### Race
There is no FDA guidance on the use of Polymyxin B  with respect to specific racial populations.

### Renal Impairment
PATIENTS WITH RENAL DAMAGE AND NITROGEN RETENTION SHOULD HAVE REDUCED DOSAGE.
NEUROTOXIC REACTIONS MAY BE MANIFESTED BY IRRITABILITY, WEAKNESS, DROWSINESS, ATAXIA, PERIORAL PARESTHESIA, NUMBNESS OF THE EXTREMITIES, AND BLURRING OF VISION.  THESE ARE USUALLY ASSOCIATED WITH HIGH SERUM LEVELS FOUND IN PATIENTS WITH IMPAIRED RENAL FUNCTION AND/OR NEPHROTOXICITY.

### Hepatic Impairment
There is no FDA guidance on the use of Polymyxin B in patients with hepatic impairment.

### Females of Reproductive Potential and Males
There is no FDA guidance on the use of Polymyxin B in women of reproductive potentials and males.

### Immunocompromised Patients
There is no FDA guidance one the use of Polymyxin B in patients who are immunocompromised.

# Administration and Monitoring

### Administration
- Parenteral
- Intravenous
- Intramuscular
- Intrathecal
- Topical
- Ophthalmic

### Monitoring
Baseline renal function should be done prior to therapy, with frequent monitoring of renal function and blood levels of the drug during parenteral therapy.

# IV Compatibility
There is limited information regarding IV Compatibility of Polymyxin B in the drug label.

# Overdosage
Inadvertent overdosage can cause Neurotoxic reactions:  Facial flushing, dizziness progressing to ataxia, drowsiness, peripheral paresthesias (circumoral and stocking glove), apnea

# Pharmacology

## Mechanism of Action
- Polymyxin B sulfate has a bactericidal action against almost all gram-negative bacilli except the Proteus group.  Polymyxins increase the permeability of the bacterial cell membrane leading to death of the cell. All gram-positive bacteria, fungi, and the gram-negative cocci, are resistant to polymyxin B. Appropriate methods should be used when performing in vitro susceptibility testing of polymyxin B 1,2,3. The following in vitro susceptibility test criteria should only be used for interpreting the results of polymyxin B susceptibility testing against P. aeruginosa when the indicated quality control parameters are met during testing.

## Structure
- Polymyxin B for Injection, USP is one of a group of basic polypeptide antibiotics derived from B polymyxa (B aerosporous).  Polymyxin B sulfate is the sulfate salt of Polymyxins B1 and B2, which are produced by the growth of Bacillus polymyxa (Prazmowski) Migula (Fam. Bacillacea).  It has a potency of not less than 6,000 polymyxin B units per mg, calculated on the anhydrous basis.  The structural formulae are:
Each vial contains 500,000 polymyxin B units for parenteral or ophthalmic administration.
Polymyxin B for Injection, USP 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 solutions 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.

## Pharmacodynamics
There is limited information regarding Pharmacodynamics of Polymyxin B in the drug label.

## Pharmacokinetics
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.

## Nonclinical Toxicology
There is limited information regarding Nonclinical Toxicology of Polymyxin B in the drug label.

# Clinical Studies
There is limited information regarding Clinical Studies of Polymyxin B  in the drug label.

# How Supplied
- Polymyxin B for Injection, USP, 500,000 polymyxin B units per vial is supplied as follows.

## Storage
- Store at 20 to 25C (68 to 77F).
- Retain in carton until time of use.
- Product must be stored under refrigeration, between 2 to 8C (36 to 46F) and any unused portion should be discarded after 72 hours.
- This container closure is not made with natural rubber latex.

# Images

## Drug Images

## Package and Label Display Panel

# Patient Counseling Information
- Patients should be counseled that antibacterial drugs including polymyxin B should only be used to treat bacterial infections.  They do not treat viral infections (e.g., the common cold).  When polymyxin B is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed.  Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by polymyxin B or other antibacterial drugs in the future.
- Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic. If this occurs, patients should contact their physician as soon as possible.

# Precautions with Alcohol
- Alcohol-Polymyxin B interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

# Brand Names

# Look-Alike Drug Names
- A  B

# Drug Shortage Status

# Price