polymyxin B/bacitracin topical

Action and Spectrum

Actions and Spectrum: 

Polymyxin B and bacitracin are both antibiotics that are used to treat bacterial infections. Polymyxin B is a polypeptide antibiotic that is active against gram-negative bacteria and is commonly used to treat infections of the urinary tract, bloodstream, and respiratory tract. bacitracin is a polypeptide antibiotic that is active against gram-positive bacteria and is commonly used as a topical ointment to treat skin infections. Both antibiotics have a narrow spectrum of activity, meaning they only target specific types of bacteria and may not be effective against a wide range of infections.

Drug Interaction

Adverse Reaction

Frequency Defined  

<1% 

Allergic contact dermatitis 

Black Box Warning

Black Box Warning 

These antibiotics have a black box warning due to the potential for serious and potentially fatal allergic reactions. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Hypersensitivity to polymyxin B or bacitracin 

Caution: 

• Use with caution in patients with kidney impairment, as polymyxin B can accumulate in the body and cause nephrotoxicity 
• Avoid using in combination with other nephrotoxic drugs, such as aminoglycosides 
• Use with caution in patients with a history of allergies or asthma, as polymyxin B and bacitracin can cause allergic reactions 
• Avoid using in the eyes, as polymyxin B and bacitracin can cause severe irritation and toxicity 
• Use with caution in neonates and infants, as polymyxin B and bacitracin can cause neurotoxicity and ototoxicity. 

Pregnancy / Lactation

Pregnancy warnings:     

US FDA pregnancy category: C 

Lactation:   

Excreted into human milk is known  

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were lack of studies on pregnant women and no evidence of risk to the foetus in animal experiments.   

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.   

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology:  

Polymyxin B and bacitracin are both antibiotics that are commonly used to treat bacterial infections. 

Pharmacodynamics: 

Polymyxin B is a polypeptide antibiotic that is derived from the soil bacterium Bacillus polymyxa. It works by binding to the cell membrane of gram-negative bacteria and disrupting the integrity of the membrane, leading to the death of the bacteria. It is primarily used to treat infections caused by gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. 

Bacitracin is a polypeptide antibiotic that is also derived from a soil bacterium, Bacillus subtilis. It works by inhibiting the synthesis of the bacterial cell wall, leading to the death of the bacteria. It is primarily used to treat skin and soft tissue infections caused by gram-positive bacteria such as Staphylococcus aureus and Streptococcus pyogenes. 

Pharmacokinetics:  

Absorption  

polymyxin B and bacitracin are both antibiotics that are typically administered topically (applied to the skin) or locally (injected into a specific area). They are not intended for oral or systemic use, so they do not undergo absorption through the gastrointestinal tract.  

Distribution  

Once applied or injected, the drugs will travel to the area of infection. Polymyxin B is primarily a bactericidal agent, which means it kills bacteria, while bacitracin is primarily a bacteriostatic agent, which means it prevents bacteria from growing. They both have a relatively low tissue distribution and are not known to cross the blood-brain barrier.  

Metabolism  

polymyxin B and bacitracin are not known to be metabolized by the body and do not have active metabolites.  

Elimination and Excretion  

Both drugs are eliminated from the body primarily through the kidneys. The elimination half-life of polymyxin B is about 1-2 hours, and the elimination half-life of bacitracin is about 2-4 hours. This means that half of the drug will be eliminated from the body within 1-4 hours after administration.  

Adminstartion

Administration:  

Topical Administration  

They are usually administered through topical applications, such as in the form of ointments, creams, or drops.  

polymyxin B is a polypeptide antibiotic that is effective against Gram-negative bacteria, including those that are resistant to other antibiotics. It works by binding to the cell membrane of the bacteria, causing changes that lead to the leakage of vital cellular components, ultimately resulting in the death of the bacteria.  

bacitracin is a polypeptide antibiotic that is also effective against Gram-positive bacteria, including those that are resistant to other antibiotics. It works by inhibiting the bacteria’s ability to make cell walls, which ultimately leads to the death of the bacteria.  

The combination of polymyxin B and bacitracin is often used to treat skin and eye infections caused by susceptible strains of bacteria. It is also commonly used as a prophylactic treatment to prevent infections in patients with burns, skin grafts, or other types of open wounds.  

Patient Information Leaflet

Patient information leaflet 

Generic Name: polymyxin B/bacitracin topical 

Why do we use polymyxin B/bacitracin topical? 

ketoconazole topical is used to treat fungal skin infections caused by a variety of organisms, such as Candida, Malassezia, and Epidermophyton. These infections can manifest as a variety of skin conditions, including tinea (athlete’s foot, jock itch, ringworm), seborrheic dermatitis, and pityriasis versicolor. The medication works by preventing the growth and reproduction of fungal cells, ultimately leading to the resolution of the infection.