Polymyxin B
a. Drug class:
b. Uses/condition treated
c. Side effects:
d. Contraindications:
e. Routes of administration:
The correct answer and explanation is:
Polymyxin B
a. Drug Class:
Polymyxin B belongs to the class of polymyxins, which are antibiotics that work by disrupting the bacterial cell membrane. Specifically, it is a cyclic peptide antibiotic.
b. Uses/Condition Treated:
Polymyxin B is used primarily to treat infections caused by gram-negative bacteria, especially Pseudomonas aeruginosa, Escherichia coli, Klebsiella species, and Enterobacter species. It is typically employed for infections in wounds, burns, eyes, and the urinary tract, as well as systemic infections in more severe cases. It can also be used as part of a combination therapy in multidrug-resistant infections.
c. Side Effects:
While effective, Polymyxin B has notable side effects. Common side effects include nephrotoxicity (kidney damage), especially with prolonged use or in patients with existing kidney problems. Neurotoxicity is another concern, causing symptoms such as numbness, tingling, dizziness, and in severe cases, seizures. Other side effects can include allergic reactions like skin rash, pruritus (itching), and fever. Respiratory distress can also occur in some cases, particularly if the drug is administered intravenously or via inhalation.
d. Contraindications:
Polymyxin B is contraindicated in individuals with known hypersensitivity to polymyxins. It should be used cautiously in those with pre-existing kidney disorders, as it may exacerbate renal toxicity. It should be avoided in pregnant women unless absolutely necessary, as it falls under category C for pregnancy, meaning there is a potential risk to the fetus.
e. Routes of Administration:
Polymyxin B can be administered via several routes depending on the nature and severity of the infection. The intravenous route is often used for systemic infections. It is also available as topical ointments (used for eye and skin infections) and as inhalation therapy for respiratory infections. For urinary tract infections, it may be instilled directly into the bladder.
Polymyxin B remains an important agent against multidrug-resistant bacteria, but its use is restricted due to its potential toxicity.