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45 Cards in this Set
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Tetracyclines (drugs):
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Chlortetracycline - short-acting
Oxytetracycline - short-acting Tetracycline - short-acting |
Demeclocycline - intermediate
Methacycline - intermediate Doxycycline - long-acting Minocycline - long-acting Tigecycline - extremely long-acting |
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Tetracyclines (MOA):
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Inhibit bacterial protein synthesis by reversibly binding to 30S ribosome
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Tetracyclines (Indications):
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Broad-spectrum: G(+), G(-), anaerobes; rickettsiae, clamydia, vibrio sp., mycoplasma, spirochetes and some protozoa
In combination regimens to treat gastric and duodenal ulcer caused by Helicobacter pylori |
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Tetracyclines (Resistance):
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Ribosome protection
Increased efflux (active transport pump) Impaired influx Enzymatic inactivation Tetracycline-resistant strains may be susceptible to doxycycline, minocycline, & tigecycline |
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Tetracyclines (Kinetics):
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Doxycycline & minocycline 95-100% absorbed (oral administration)
Tigecycline: IV only Factors affecting oral absorption Food, divalent cations, dairy products & antacids, alkaline pH |
Drug Distribution
Distributed widely to tissues and body fluids (not CSF) Cross the placenta to reach the fetus and are excreted in milk Metabolized in liver and eliminated in urine (not doxycycline or tigecycline) |
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Tetracyclines (Adverse Reactions):
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GI effects (Nausea & vomiting; Pseudomembranous colitis)
Damage on teeth & bone (pregnant women or young children) Liver toxicity |
Kidney toxicity
Local tissue toxicity: venous thrombosis (IV) Photosensitization Vestibular Reactions: dizziness, vertigo, nausea |
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Aminoglycosides (drugs):
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Streptomycin
Neomycin Kanamycin |
Amikacin
Gentamicin Tobramycin Netilmicin |
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Aminoglycosides (MOA):
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Inhibit bacterial protein synthesis by irreversibly binding to 30S ribosome
Bactericidal Interferes with proofreading process of mRNA Inhibits peptide-tRNA translocation from A to P site |
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Aminoglycosides (Indications):
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Active against G(-) & G(+) bacteria (not anaerobes)
Often combined with a β-lactam antibiotic for the treatment of serious infections or infective endocarditis caused by enterococci |
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Aminoglycosides (Resistance):
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Plasmid-encoded aminoglycoside-modifying enzyme
Altered ribosomal binding sites |
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Aminoglycosides (Kinetics):
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Poor GI absorption. Usually IV/IM
Once daily dosing Eliminated by kidney |
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Aminoglycosides (Adverse Reactions):
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Significant toxicity (> 5 days of use)
Ototoxicity (irreversible) Nephrotoxicity (reversible) |
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Streptomycin:
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Aminoglycoside
Mainly used as a 2nd line agent to treat tuberculosis Treat Bubonic Plague |
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Neomycin:
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Aminoglycoside
Not safe for systemic use (extremely nephrotoxic) Only used topically or orally |
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Kanamycin & paromomycin:
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Aminoglycosides
Closely related to neomycin, but less toxic |
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Amikacin:
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Aminoglycoside
Similar to kanamycin, but less toxic Treat bacteria that are resistant to other aminoglycosides or tuberculosis (2nd line agent) |
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Gentamicin:
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Aminoglycoside
Most often used aminoglycoside |
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Tobramycin:
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Aminoglycoside
Used interchangeaby with gentamicin Treat infections caused by Pseudomonas aeruginosa |
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Netilmicin:
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Aminoglycoside
Active against some bacteria that are resistant to gentamicin or tobramycin |
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Spectinomycin:
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Structurally related to aminoglycosides
Used IM solely to treat drug-resistant gonorrhea in patients who are allergic to penicillin |
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Macrolides (drugs):
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Erythromycin
Clarithromycin Azithromycin Thelithromycin - Ketolides |
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Macrolides (MOA):
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Bind to and inhibit 50S ribosomal subunit (inhibit translocation process)
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Macrolides (Indications):
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Effective against G(+) organisms
Bacteriostatic or bactericidal (at high conc.) Corynebacterial infections (diphtheria, corynebacterial sepsis, erythrasma |
Respiratory, neonatal, ocular, or genital chlamydial infections
Community-acquired pneumonia (CAP) Staphylococcal infections in penicillin-allergic patients |
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Macrolides (Resistance):
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Active efflux or decrease cell permeability
Hydrolyzed by esterases Modification of the ribosomal binding site (chromosomal mutation; by inducible or constitutive methylase) |
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Macrolides (Kinetics):
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Erythromycin is destroyed by stomach acid (must be administered with enteric coating)
Clarithromycin and azithromycin are more stable in stomach acid and are better absorbed (food affects absorption) Erythromycin & clarithromycin both inhibit liver cytochrome p450 enzymes |
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Macrolides (Adverse Reactions):
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GI intolerance
Liver toxicity (Acute cholestatic hepatitis) |
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Telithromycin:
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Ketolide
Many macrolide-resistant pathogens are susceptible to ketolides (once daily dosing) Inhibits p450 enzymes Indicated for treatment of respiratory infections GI toxicity & severe liver failure |
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Clindamycin (MOA):
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Inhibits bacterial protein synthesis by binding to the 23S rRNA* of the 50S subunit
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Clindamycin (Indications):
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Broad spectrum (esp active against anaerobes)
Treat infection caused by bacteroids and other anaerobes associated with mixed infections Recommended for prophylaxis of endocarditis in patients with valvular heart disease who are undergoing dental procedures |
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Clindamycin (Resistance):
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Mutation of the ribosomal site
Modification of the binding site by a constitutively expressed methylase Enzymatic inactivation |
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Clindamycin (Adverse Reactions):
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Increased risk for diarrhea & colitis due to Clostridium difficile
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Chloramphenicol (MOA):
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Binds to 50S ribosome (inhibits the peptidyltransferase reaction)
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Chloramphenicol (Indications):
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Bacteriostatic (broad-spectrum)
Active against aerobic & anaerobic G(+) & G(-) Alternative agent for treating meningitis in patients who are allergic to penicillin |
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Chloramphenicol (Resistance):
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Decreased drug permeability
Production of plasmid-encoded chloramphenicol acetyltransferase |
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Chloramphenicol (Kinetics):
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Inactivated in the liver (via conjugation) & excreted in urine
Dosage adjustment is needed in patients with hepatic failure Used topically in the treatment of eye infections (excellent tissue penetration) |
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Chloramphenicol (Adverse Reactions):
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Increased risk for diarrhea & colitis due to Clostridium difficile
Aplastic anemia (irreversible) Grey baby syndrome Newborns lack an effective glucuronic acid conjugation mechanism for the degradation of chloramphenicol; drug accumulation causing hypotension, cyanosis and death |
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Streptogramins (MOA):
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Binds to 50S ribosomal subunit
Bactericidal |
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Streptogramins (Indications):
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Active against G(+) cocci (including vancomycin-resistant staphylococci (VRSA) and Enterococcal faecium (VRE)
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Streptogramins (Resistance):
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Modification of the quinupristin binding site by a methylase
Enzymatic inactivation of dalfopristin Efflux |
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Streptogramins (Kinetics):
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Inhibits CYP3A4* enzyme (drug interactions) CYP34A metabolizes warfarin, diazepam, non-nucleoside reverse transcriptase inhibitors, and cyclosporine
Streptogramin B + streptogramin A (30:70) IV |
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Streptogramins (Adverse Reactions):
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Infusion-related pain & arthralgiamyalgia syndrome (muscle pain)
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Quinupristin-dalfopristin:
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AKA streptogramins
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Linezolid (MOA):
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Inhibits protein synthesis by binding to the 23S rRNA of the 50S subunit (blocks the initiation step of the protein synthesis)
Bacteriostatic |
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Linezolid (Indications):
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Active against many G(+) organisms
Should be reserved for treatment of infections caused by multidrug-resistant G(+) bacteria (MRSA or VRE) |
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Linezolid (Adverse Reactions):
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Hematologic toxicity
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