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Pharmacology of Antibacterial Drugs III - Coggle Diagram
Pharmacology of Antibacterial Drugs III
Protein Synthesis Inhibitors
Aminoglycosides
Very complex actual mechanisms and lots of them. Generally inhibit
initiation
and
elongation
Gentamicin
Extended spectrum (
gram+ and gram-, aerobes
)
Used against
serious gram- infections
Administerd via IV
Synergistic with ß-lactams and vancomycin (cell wall drugs - let more gentamicin into the cell)
Resistance in gram- aerobes is usually due to expression of drug modifying enzymes
Has a
post antibiotic effect
it is irreversible - even though it's not in our plasma anymore, it's still in the bug killing it
Adverse effects
Renal toxicity (dosed only ever 24 hours)
Ototoxicity
Neuromuscular paralysis
Not actually used all that frequently clinically because of high toxicity
Tetracyclines
Inhibit
tRNA binding
Tetracycline-HCL and Doxycycline
Tetracycline is cleared renally
Doxycyline is most likely cleared hepatically
Broad spectrum
Multiple forms of the drug
Absorption is variable due to interaction with foods or multivalent cations
Useful for
Mycoplasmal
and intracellular infections
Some activity against protozoal infections (malaria)
Used in the treatment of acne
Adverse effects
Superinfection cuz broad spectrum
Because they are chelators, they can't be given to kids <8 yo or pregnant/nursing women because it will affect bone development
renal toxicity
photosensitization (doxycycline) - legit, actually don't go in the sun with this cuz bad
Drug interactions
Interact with multivalent cations (ie. antacids, iron, calcium supplements)
Can affect action of other drugs by altering intestinal flora (eg. reducing vit K bacteria = increase in warfarin action)
Clindamycin
Inhibits
Peptide bond formation
Extended spectrum (
gram+ and anaerobic gram-
)
Therapeutic uses
Treating anaerobic infections
Alternate drug for treating aerobic gram+ cocci in patients allergic to ß-lactam drugs
Good penetration into bone for dental use
Resistance
erm methylase
Superinfection danger
Macrolides
Inhibit
Peptide bond formation
Erythromycin and Azythromycin
Narrow spectrum (
gram+ primarily
)
Also active against Mycoplasma and Chlamydia, which are intracellular bugs
Used commonly for lots of infections
Resistance
erm. methylase
Newer macrolides (
Azythromycin
) are better tolerated with longer half lives and more extended spectrum
Adverse effects
cholestatic hepatitis
Epigastric distress
Drug interactions
Can inhibit P450 mediated metabolism of other drugs
Oxazolidanones
Inhibit
mRNA binding
(Initiation)
Linezolid
Bacteriostatic
Active against
gram+ organisms
Adverse effects
myelosuppression
Usually used to treat drug resistant infections (ie. after vancomycin)
Topoisomerase Inhibitors
Fluoroquinolones
Mechanism
Inhibits typ 2 topoisomerase and disrupts DNA synthesis
Bactericidal
Extended spectrum (
gram+ and gram- aerobes
)
Also active against Mycoplasma, chlamydia, mycobacteria
Useful for variety of infections (ie. urinary, respiratory, GI)
Absorbed well orally
Adverse effects
Can basically be used in anyone who is >18 yo and is not a pregnant or nursing mother
May cause cartilage degeneration in young kids
Can cause seziures as a GABA inhibitor
Superinfections
Can lead to Achilles tendon rupture even in completely healthy people
Can inhibit metabolism of other drugs, ie. caffeine, and is also a concern with multivalent cations (antacid, iron, calcium)
Tuberculosis
Important Issues
Mycobacteria are intrinsically resistant to most antibacterial drugs (slow growing, can become dormant, exists in intracellular sites, unusual cell wall)
Pharmacological issues
Limited number of drugs available for treatment
Treatment requires continuous prolonged therapy (6-9 mo)
Adverse drug effects and interactions
Compliance is awful
Isoniazid
Bactericidal
Inhibits synthesis of mycelia acid
CYP450 inhibitor
Rifampin
Inhibits RNA polymerase
Bactericidal
Causes hepatotoxicity
Increased metabolism of other drugs
Ethambutol
Cell wall drug
Bactericidal
can cause red-green colorblindness
Pyrazinamide
Prodrug activated by the bacteria
Don't know the mechanism
Bactericidal
Cause liver toxicity and limits secretion of uric acid (gout)
All four drugs are used for the first two months, then Isoniazid and Rifampin are used for the next 4-7 months