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36 Cards in this Set

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Protein Synth Inhibitors: OXAZOLADINONES: Linezolid
Prevents formation and initiation complex and 70S ribosomal complex, binds 50S subnit and prevents protein synthesis.
Protein Synth Inhibitors: OXAZOLADINONES: Linezolid... Pathogen spectrum
Bacteriostatic against Gram Pos, VRE, VSE, MRSA, MRSE, staph haemolyticus, Strep pneumo (incl PCN resistant strains)

Good oral and IV
Protein Synth Inhibitors: OXAZOLADINONES: Linezolid ... Mech of Resistance and Adv effects
mutation of 23 S rRNA prevents binding of drug

Adv effects: inhibits MAO, GI, thrombocytopenia, anemia, myelosuppression.
Protein Synth Inhibitors: TETRACYCLINS: tetracycline, doxycycline
Most commonly used ones are Doxycycline and Minocycline. The other ones are used in ophthalmic prep.

broad spectrum bacteriostatic against Gram POS, Neg aerobic and anaerobic bacteria.
Protein Synth Inhibitors: TETRACYCLINS: tetracycline, doxycycline ... Mech of action
binds 30 S, prevents binding of aminoacyl tRNA during protein synthesis

In Gram Neg, cross outer membrane by passive diffusion through porin channel and active transport through plasma membrane (which mammalian cells lack).
Protein Synth Inhibitors: TETRACYCLINS: tetracycline, doxycycline ... PHARMACOKINETICS
oral absorption incomplete but adequate, absorption impaired by food (except doxycycline), dairy products, antacids, alkaline pH.
Protein Synth Inhibitors: TETRACYCLINS: tetracycline, doxycycline ... MECH of Resistance
resistance to one tetracycliine confers resistance to others.

decrease accumulation due to decrease influx or acquiring efflux mech.

decrease access to ribosome b/c of ribosome protecting proteins (Tet-O)

Enzymatic activatin of drug.
Protein Synth Inhibitors: TETRACYCLINS: tetracycline, doxycycline ... adverse effects
GI incl Pseudomonas enterocolitis, teeth discoloratin, bone deformatin, growth inhibition in children, local tissue damage, renal and hepatic toxicity, photosensitivity.
Protein Synth Inhibitors; GLYCYLCYCLINES: tigecycline
binds 30S, inhibits binding aminoacyl-tRNA into the A site of ribosome, preventing incorporation of the amino acid residues into the elongating peptide chain.
Protein Synth Inhibitors; GLYCYLCYCLINES: tigecycline ... Pharmacokinetics
IV admin, broad distribution, primarily excreted in feces and urine.. not extensively metabolized.
Protein Synth Inhibitors; GLYCYLCYCLINES: tigecycline ... Mech of Resistance
Substrate for TetX

AcrAB transport system appears to be assoc w/ intrinsic reduced susceptibility to tigecycline in P. mirabilis
Protein Synth Inhibitors; GLYCYLCYCLINES: tigecycline ... ADVERSE EFFECTS
*** ADULTS ONLY *** NOT RECOMMENDED FOR CHILDREN, INFANTS, OR PREGNANT OR NURSING WOMEN.

GI issues

Drug interractions with Warfarin, and ORAL CONTRACEPTIVES.
Protein Synth Inhibitors; AMINOGLYCOSIDES: streptomycin
contain amino sugars linked to an aminocyclitol ring by glycosidic netilmicin


binds 30S (site within 16S rRNA) IRREVERSIBLY inhibiting protein synthesis

Mech incl.interfere w/ formation of initiation complex, mRNA code misreading resulting in incorportion of incorrect amino acids, premature termination by dissociation of the polysomes.
Protein Synth Inhibitors; AMINOGLYCOSIDES: streptomycin ... PATHOGEN SPECTRUM
broad spectrum bactericidal activity but PRIMARILY against GRAM NEGATIVE bacteria.

In gram neg bacteria, cross outer membrane via diffusion and inner membrane via active transport (transp inhibited by divalent cations, hyperosmolarity, low pH and ANAEROBIC conditions.

WOULD NOT WORK AGAINST ANAEROBES.
Protein Synth Inhibitors; AMINOGLYCOSIDES: streptomycin ... PHARMACOKINETICS
Synergy with beta lactam antibiotics, has PAE

low accumulation in CSF (except during active inflammation.

POOR ORAL absorption, rapid absorption via IM or IV. Rapid excretion by kidneys
Protein Synth Inhibitors; AMINOGLYCOSIDES: streptomycin .. Mech of Resistance
acquisition of inactivating enzymes (acetylase, adenylase, phsphorylase (plasmid encoded)).

secondary resistance if drug fails to permeate inner bacterial membrane.
Protein Synth Inhibitors; AMINOGLYCOSIDES: streptomycin .. adverse effects
Ototoxicity (irreversible)

Nephrotoxicity (reversible.. avoid using with loop diuretics)

NM blockadge (with high doses), may result in respiratory paralysis

Nerve dysfunction, allergic skin rxn and contact dermatitis.
Protein Synth Inhibitors; CHLORAMPHENICOL
very cheap but too many toxicity... no more in the US.

enters by facilitated diffusion, binds reversibly the 50S to prevent binding of aminoacyl tRNA in A site, inhibiting the peptidyl transferase step of protein synthesis.
Protein Synth Inhibitors; CHLORAMPHENICOL .. Pathogen spectrum
Bactericidal for H. influenza, Strep pneumo, N. meningitidis.

Bacteriostatic for most microorganisms.
Protein Synth Inhibitors; CHLORAMPHENICOL ... Pharmacokinetics
rapid abosorption via oral or IV, well distributed w/ therapeutic distr. in CNS.

CROSS PLACENTA.

half life been correlated w/ plasma bilirubin concentration (that's why infants can't process it).
Protein Synth Inhibitors; CHLORAMPHENICOL .. Mech of RESISTANCE
decrease influx

chloramphenicol acetyl transferase (plasmid encoded)
Protein Synth Inhibitors; CHLORAMPHENICOL .. ADVERSE EFFECTS
Bone Marrow: direct tox (dose related) normocytic anemia, erythroid suppression, reversible.

Indirect bone tox: allergic rxn resulting in blodd dyscrasias resulting in aplastic anemia, reversible but fatal, macular or vesicular rashes

Gray baby syndrome: inadequate glucuronic acid conjugation

Drug Intxn: inhibits CYP3A4

ANTAGONIZES macrolides, and clindamycin (bind similar position on ribosome, thus competing)
Protein Synth Inhibitors; MACROLIDES -- erythromycin, clarithromycin, azithromycin
usually bacteriostatic but bactericidal in high concentration

Binds 50S and inhibit translocation step of protein synthesis
Protein Synth Inhibitors; MACROLIDES -- erythromycin, clarithromycin, azithromycin -- Pharmacokinetics
Erythromycin inactivated by gastric acid but absorbed in upper small intestine. Clarithromycin and azithromycin acid stable and better at tissue penetration

Azo group insertion into lactone group increases bioavailability and stability.

wide distro EXCEPT CSF

Elim: erythro and azithro via liver; clarithro through renal and non-renal
Protein Synth Inhibitors; MACROLIDES -- erythromycin, clarithromycin, azithromycin -- Mech of RESISTANCE
Efflux

methylase production that modifies ribosomal target leading to decreased drug binding.

MLSb determinants: resistance to macrolides, liconsamides and streptogramin B

Hydrolysis by esterases

mutation of ribosomes - specificially 23 S rRNA to which macrolides bind
Protein Synth Inhibitors; MACROLIDES -- erythromycin, clarithromycin, azithromycin - ADVERSE EFFECTS
some hypersensititivy rxn, GI, hepatic (cholestatic hepatitis), arrhythmia (prolong QT with VT)

Drug intxn: erythromycin and clarithromycin (but not azithromycin) inhibit hepatic enzymes (CYP3A4)

Erythromycin intx with liver p450s inhibiting metabolism of other drugs.
Protein Synth Inhibitors; LINCOSAMIDES; clindamycin
bacetriostatic gram pos, some macrolide-resistant strain

active against anaerobes

Binds P and A site on 50S and supress protein synthesis
Protein Synth Inhibitors; LINCOSAMIDES; clindamycin -- pharmacokinetics
good oral absorption, wide distr. includ BONES, crosses placenta but not BBB

metab.secr in urine and bile
Protein Synth Inhibitors; LINCOSAMIDES; clindamycin -- Mech of Resistance and Adverse effects
ribosomal methylation (MLSb) which is plasmid encoded


GI: Pseudomonas entrocolitis assoc w/ overgowth of C. difficile

NMJ inhibition

Skin rashes in HIV pts more commonly
Protein Synth Inhibitors; Streptogramin B (quinupristin) and Streptogramin A (dalfopristin)
Streptogramin B binds 50S and inhibits translocation step, occupies same location as macrolides.

Streptrogramin A binds nearby and induces a conformational change in the 50S rib subunit, enhancing quinupristin binding.


Synecrid: combo of streptogramin B with streptogramin A.
Protein Synth Inhibitors; Streptogramin B (quinupristin) and Streptogramin A (dalfopristin) -- Pharmacokinetics
IV only, short half life, elim mainly by biliary excretion.

combo more than additive for each other.
Protein Synth Inhibitors; Streptogramin B (quinupristin) and Streptogramin A (dalfopristin) -- Resistance
Streptogramin A: efflux and acetyl transferases

Methylase modification of ribosomal binding site (MLSb) and lactonases.

Adverse effect: infusion related pain and phlebitis
Protein Synth Inhibitors; Streptogramin B (quinupristin) and Streptogramin A (dalfopristin) - pathogen spectrum
bactericidal against Gram Positive cocci, inactive against Gram Negative strain

reserved for vancomycin-resistant strains of E.faecium or multi drug resistant Gram positive organisms
Protein Synth Inhibitors; KETOLIDES; telithromycin
50S subunit binding similar to macrolides

mainly Gram positive and neg bacilli and cocci and MYCOBACTERIA

reserved for community acq pneumonia from Strep pneumo.

active even against erythromycin-resistant strains

Mostly bacteriostatic but bactericidal against strep pneumonia
Protein Synth Inhibitors; KETOLIDES; telithromycin - pharmacokinetics
hepatic metabolism, good tissue distribution especially PULMONARY.
Protein Synth Inhibitors; KETOLIDES; telithromycin -- adverse effects
CRITICAL ADVERSE EFFECTS: Hepatic toxicity and failure, wathc for jaundice, abd pain, dark urine.

Drug Itxn: inhibitor of CYP3A4, increases concentration of cisapride, pimozide, simvastatin, midazolam

b/c of risk, no longer recommended for sinusitis, chronic bronchitis or tonsillitis/pharyngitis