Card Set Information
Tetracycline mechanism of action
protein synthesis inhibitors
bindd to 30s subunit of bacterial ribosome
Blocks aminoacyl-TtRNA to acceptor site on the mRNA-ribosome complex.
prevents addition of amino acids to growing peptide.
Tetracycline is a derivative of what?
polycyclic naphthacene carboxamide
Tetracycline (general info)
hydrochloride more soluble
Tetracycline hydrochlorides solution are fairly stable (except chlortetracycline
When do tetracyline loose activity?
when they chelate into divalent metal ions
this interfere with absorption and activity
treat infection that are resistant to other antimicrobics including conventional tetracyclines
Tetracycline antimicrobial activity
broad spectrum bacteriostatic, inhibit protein synthesis
against gram+ and gram -
enter microorganism by passive diffusion and in part by energy dependent process of active transport
Tetracycline resistant strains may be susceptible to...
doxycyline, minocycline, and tigycycline which are poor substrates for efflux pump.
Mechanism 1 of resistance for tetracycline
impaired influx or increase efflux by an active transport protein pump.
most important: are production of efflux pump and ribosomal protection.
Mechanims 2 of resistance for tetracycline
ribosome protection due to production of proteins that interfere with tetracycline binding to ribosome
Mechanism 3 of resistance for tetracycline
enzymatic inactivation of tetracycline
Mechanism of action of protective protein for tetracycline resistance
: blocking tetracycline from binding to ribosome
: binding to ribosome and distorting the structure to still allow t-RNA binding while tetracycline is bound
: binding to the ribosome and dislodging tetracycline
ribosomal protection protein expressed by gram + to create resistance against tetracycline, doxycyline, and minocycline
but not tigecycline
Steric hindrance effect due to t-butylglycylamido substituent
rarest type of resistance
acetyl group is added to tetracycline causeing inactivation of drug.
Absorption for oral administration for tetracyclines
30% for chlortetracycline
60-70% for tetracycline, oxytetracycline, demeclocycline, and methacycline
95-100% for doxycyline and minocycline
poor oral absorption for tigecycline and must be administered intravenously
portion of tetra dose remains in gut and modifies intestinal flora, excreted in feces
Tetracycline occurs mainly where?
upper small intestines
What interfers with tetracycline absorption?
food (except doxy and mino), divalent cations, dairy products and antacids, and alkaline pH
How are tetracylines recommended to take?
with a full glass of water
1 hours before and 2 hours after eating
Specially buffered tetracyclines are used for what?
Tetracyclines are what percent bound to proteins?