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Index
 »Â
ORG MED LEC
 »Â
Tetracyclines
 »Â
DRUGS
level: DRUGS
Questions and Answers List
level questions: DRUGS
Question
Answer
Naturally Occuring Tetracyclines
1 Tetracycline 2 Chlortetracycline 3 Oxytetracycline 4 Demeclocycline
Semisynthetic occurring Tetracyclines
1 Doxycycline 2 Minocycline 3 Tigecycline 4 Methacycline 5 Rolitetracycline
Pharmacophore of this group
Sancycline
Most widely used, cheap antibiotic Drug of Choice for ACNE Its blood level after oral administration is irregular; due to inactivation by acidic medium in stomach or basic medium in intestine
Tetracycline
Isolated from Streptomyces aureofaciens Its used as orally as capsules to avoid bitter taste & may be administered parenterally (IV) 7-chloro is e-withdrawing group that increase activity
Chlorotetracycline
Produced by fermentation of mutant strain of Streptomyces aureofaciens It lacks 6-methyl of tetracycline -> present as secondary alcohol -> more stable
Demeclocycline
Produced by fermentation of Streptomyces rimosis The MOST HYDROPHILIC tetracycline
Oxytetracycline (Terramycin)
Produced by chemical modification of Oxytetracycline Removal of 6-OH -> more stability against acids & bases -> longer serum half life The chemical precursor for Doxycycline
Methacycline
One of the most important of current tetracyclines Given to UREMIC PATIENTS with infections outside urinary tract Its metabolite is preferentially EXCRETED VIA BILE INTO FECES Causes GIT DISTURBANCE
Doxycycline (Vibramycin)
Synthesis of Doxycycline
1 From methacycline by direct reduction 2 From oxytetracycline HCL by catalytic hydrogenation
The MOST LIPID SOLUBLE of tetracycline-class antibiotics giving it greatest penetration into the prostate and brain Also greatest amount of CNS-related side effects such as VERTIGO
Minocycline
Minocycline semi-synthesis is from __
Demeclocycline by catalytic reaction and reductive methylation
Formed by condensation of Tetracycline + Pyrrolidine + Formaldehyde in the presence of t-butyl alcohol (MANNICH REACTION) PRODRUG for tetracycline Highly water soluble & suitable for oral and parenteral administration Activated by spontaneous decomposition NOT by action of amidase
Rolitetracycline