Pilch - Antibiotics Flashcards
Protein synthesis inhibitors
Takes advantage of the difference bwteen the 80S of mammalian ribosomes and the 70S of bacteria.
- some inhibit the 30S and some inhibit the 50S subunit.
What are the classes of drugs that inhibit the 30S subunit ?
Aminoglycosides - drugs that end in “cin”
- ex - gentamicin, streptomycin
Tetracyclines - drugs that end in “cycline”
- ex - tetracycline, doxycycline
Inhibitors of 50S subunit of ribosomes
Macrolides - drugs that end in “mycin”
- ex azithromycin
Lincosamide - Clindamycin is the only one and is the exception to the previous rule
Streptogramins - drugs end in “pristin”
Oxazolidinone - Linezolid
Aminoglycosides
Protein synthesis inhibitors that inhibits the 30S subunit of the ribosome.
- 3 mechanisms of action: blocks initiation of protein synthesis, causes premature termination, and incorporates incorrect AAs
- the fact that it incorporates incorrect AAs is specific to this class of drug and causes it to be bacteriocidal.
- This also causes it to have a postantibiotic effect because there are still misfolded proteins floating around which eventually will cause the cells to die.
Aminoglycosides - streptomycin - what is it used for?
Second line agent for tuberculosis
Aminoglycosides - Tobramycin and Gentamycin - what are they used for?
Used in cases of severe infection caused by gram-negative bacteria that are likely to be resistant to other drugs.
- often used in combination with a beta-lactam antibiotic to take advantage of synergistic effects.
Aminoglycosides - Amikacin - What is it used for?
It is often used in place of gentamicin and tobramycin because the microbes are more likely to be resistant to them but not Amikacin.
Aminoglycosides - Neomycin and Kanamycin - what are they used for?
Topical use because they are too toxic to use systemically.
- they are usually put on or injected directly into the infected site.
- When coupled with other things it is neosporin
Aminoglycosides - adverse reactions
Nephrotoxicity
- more likely when treatment persists for over 5 days
- reversible upon discontinuation of therapy.
Ototoxicity
- more likely to occur if persists longer than 5 days
- can be auditory damage such as tinnitus (ringing and high pitch hearing loss or it can be vestibular damage such as vertigo and ataxia
- damage is irreversible
Tetracyclines - mechanism of action
Protein synthesis inhibitors that bins to the 30S ribosomal subunit and prevents aminoacyl-tRNA from binding to the A-site. This blocks peptide elongation.
- it is Bacteriostatic
- works on aneorobic gram negative and gram positive organisms such as rickettsiae, chlamydiae, and mycoplasmas. Also works on Protozoa (ameba)
Tetracyclines - pharmacokinetics
- absorption is orally transmitted. Can be short, medium or long acting,
- they chelate multivitamins
- absorption is impaired by these cations. So, you have to stay away from them as well as dairy products. So, take this drug before you eat. Also don’t take antacids.
Tigecycline
A tetracycline that is administered via IV and has a much longer half life than the other ones in this class.
Tetracycline clinical use
RSRS - like a wheel it is cyclical
Rickettsial infections - Rocky Mountain spotted fever
STIs - chlamydia
Respiratory tract infections - Pnemonia
Skin and Soft Tissue infections - staph and acne
- Doxycycline is used to treat LYME DISEASE
- Tigecycline - Used to treat MRSA bacteria. Only whip it out if it multi drug resistant.
Tetracyclines - adverse reactions
GI disturbances
Bony structure and teeth - teeth can turn gray. Only happens in kids because it only works on newly forming structures.
Photosensitization - don’t prescribe it to someone who works outside all day because it can really burn them
Liver disturbances - contraindicated during pregnancy for this reason.
Macrolides - mechanism of action?
Bind to the 50S subunit and inhibit the translocation step of protein synthesis.
