C.11. Polymyxins

Question 1

What are polymyxins?

Answer 1

Polymyxins are antibiotics. 
Polymyxins B and E (also known as colistin) are used in the treatment of Gram-negative bacterial infections. They work mostly by breaking up the bacterial cell membrane. They are part of a broader class of molecules called nonribosomal peptides.

Question 2

Mechanism of action of polymyxins?
Names of polymyxins
Static or Cidic?

Answer 2

Polymyxin B and E (colistin)

Mechanism: Bind to membrane by of bacteria and altering it’s permeability

Bacteriocidic!

Question 3

spectrum:

Answer 3

Target mainly Gram - bacteria while ineffective against Gram +.

Question 4

Clinical use:

Answer 4

Topic use in ointments.
Combined with neomycin and bacitracin
infected superficial wounds.

Parental use agianst gram - baceria infection:
Pseudomonas aeruginosa
Enterobacteriacae (which are resistant to other agents)
acinobacter baumanni

Last resort drug

Question 5

Kinetics

Administartion

Answer 5

poor distribution, does not enter CNS.

parental or topical use (drops).

Question 6

adverse effect

Answer 6

nephrotoxic and neurotoxic.