The key difference between polymyxin B and colistin is that polymyxin B is mainly useful for the treatment of bacterial infections in the eye, whereas colistin is important for the treatment of multidrug-resistant Gram-negative infections.
Both polymyxin B and colistin are useful antibiotics. Antibiotics are medicine that can inhibit the growth or destroy microorganisms. These two drugs are important in treating bacterial infections. Colistin is also known as polymyxin E.
CONTENTS
1. Overview and Key Difference
2. What is Colistin
3. What is Polymyxin B
4. Similarities Between Polymyxin B and Colistin
5. Polymyxin B vs Colistin in Tabular Form
6. Summary – Polymyxin B vs Colistin
What is Polymyxin B?
Polymyxin B is an antibiotic that is useful in treating bacterial infections. The ophthalmic form of this drug is useful in treating bacterial infections of the eyes. There are a few different ways we can get this drug; injecting it into a muscle or as an infusion into a vein, injecting it into the spinal fluid, or as drops into the eye.
The most common side effects regarding polymyxin B are burning, stinging, irritation, itching, redness, blurred vision, eyelid itching, tearing, eyelid swelling or crusting, and sensitivity to light.
Mechanism of Action of Polymyxin B
What is Colistin?
Colistin is an antibiotic medicine useful as a last-resort treatment for multidrug-resistant Gram-negative infections. A common infection like this is pneumonia. This drug is also named polymyxin E. The bacteria species against which we can use this drug include Pseudomonas aeruginosa, Kiebsiella pneumoniae, and Acinetobacter. The methods of administration of this drug include injecting into a vein, injecting into a muscle or inhalation (the drug is also known as colistimethate sodium in such cases), applying it on the skin or taking it by mouth (in oral administration, the drug is named as colistin sulfate).
However, there can be some side effects of colistin. The injectable forms of this drug include side effects such as kidney problems and neurological problems. There can be some other side effects as well, including anaphylaxis, muscle weakness, and diarrhea. The construction of bronchioles is a side effect that comes from the inhaled forms of colistin.
Figure 01: Chemical Structure of Colistin
Mechanism of Action of Colistin
When considering the mechanism of action of colistin, it is a polycationic peptide having both hydrophilic and lipophilic moieties. These regions tend to react with the bacterial outer membrane through displacing magnesium and calcium bacterial counter ions in the lipopolysaccharide. These hydrophilic/hydrophobic regions can interact with the cytoplasmic membrane similar to a detergent, solubilizing the membrane in an aqueous environment which is a bactericidal event.
What are the Similarities Between Polymyxin B and Colistin?
- Both polymyxin B and colistin are useful antibiotics. Antibiotics are medicine that can inhibit the growth or destroys microorganisms.
- These two drugs are important in treating bacterial infections.
What is the Difference Between Polymyxin B and Colistin?
The key difference between polymyxin B and colistin is that polymyxin B is mainly useful in the treatment of bacterial infections in the eye, whereas colistin is important for the treatment of multidrug-resistant Gram-negative infections. Some Side effects of polymyxin B involve burning, stinging, irritation, itching, redness, blurred vision, eyelid itching, tearing, eyelid swelling or crusting, and sensitivity to light, etc. whereas side effects of polymyxin mainly involve kidney problems, and neurological problems, anaphylaxis, muscle weakness, and diarrhea.
Below is a summary of the key differences between polymyxin B and colistin in tabular form.
Summary – Polymyxin B vs Colistin
Both polymyxin B and colistin are useful antibiotics. Antibiotics are medicine that can inhibit growth or destroys microorganisms. These two drugs are important in treating bacterial infections. The key difference between polymyxin B and colistin is that polymyxin B is mainly useful for the treatment of bacterial infections in the eye whereas colistin is important for the treatment of multidrug-resistant Gram-negative infections.
Reference:
1. “Polymyxin B Ophthalmic Uses, Side Effects & Warnings.” Drugs.com, Available here.
Image Courtesy:
1. “Colistin” By Leyo – Own work (Public Domain) via Commons Wikimedia