Clindamycin and Tetracycline Antibiotics Flashcards Preview

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Flashcards in Clindamycin and Tetracycline Antibiotics Deck (43)
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MOA of clindamycin?

inhibits protein synthesis by binding mainly to the 23S RNA part of the 50S ribosomal subunit (binds to the same site as erythromycin)


Clindamycin is most effective against:

1. Aerobic gram (+) cocci - some members of the Staphylococcus and Streptococcus genera
2. Anaerobic gram (-) bacilli - some members of the Bacteroides and Fusobacterium genera


Clindamycin may be used systemically to treat

bone infections with Staphylococcus aureus, or topically to treat severe acne
available as a vaginal cream for treatment of bacterial vaginosis


Clindamycin has replaced penicillin for treatment of what?

lung abscesses and anaerobic lung and pleural space infections - also used to treat MRSA


Clindamycin is administered IV with pyrimethamine and leucovorin to treat what?

AIDS patients with encephalitis caused by Toxoplasma gondii


What limits the use of clindamycin to treat infections in which it is clearly the superior agent?

the relatively high incidence of pseudomembranous colitis and diarrhea


What is clindamycin metabolized by?

cytochrome P450 in the liver


Clindamycin penetrates the CNS in high enough concentrations to be useful in the treatment of what?

cerebral toxoplasmosis in HIV patients


How are clindamycin and its metabolites mainly excreted?

in urine and bile


Accumulation of clindamycin can occur in which patients?

patients with hepatic failure


Adverse effects of clindamycin?

diarrhea, pseudomembranous colitis, nausea, vomiting, abdominal cramps and rash, contact dermatitis (topical)


Potentially lethal condition commonly associated with clindamycin

pseudomembranous colitis


What do you treat C. diff/pseudomembranous colitis with?

metronidazole or vancomycin


What kind of foods should tetracyclines not be administered with?

foods rich in calcium because the insoluble calcium chelates are not absorbed from the GI tract


What other medications should tetracyclines not be administered with?

antacids that contain multivalent metals (ex TUMS) or with hematinics containing iron


What happens if you administer tetracyclines to children when they are forming their permanent teeth?

permanently brown or gray teeth because tetracyclines chelate calcium during formation of teeth


To minimize the pain on injection of tetracycline, what has been added to injectable formulations?

EDTA, which chelates the calcium (buffered to acidic pH where chelation is suppressed)


What should you do with discolored, old tetracycline samples?

throw them out


What are the problems with 4-epianhydrotetracycline?

it's not only inactive as an antibiotic, it is also toxic to the kidneys and can produce a Fanconi-like syndrome that can be fatal


Fanconi-like syndrome

failure of the reabsorption mechanism in the proximal convoluted tubule


Commercial samples of tetracycline are closely monitored for what?



Tetracycline MOA?

binds to the 30S ribosomal subunit and inhibits bacterial protein synthesis by blocking the attachment of the aminoacyl-tRNA to the A site of the ribosome, resulting in termination of peptide chain growth


Specifically, what do tetracyclines inhibit?

they are inhibitors of the codon-anticodon interaction


Do the tetracycline binding sites overlap with the erythromycin binding site?



Why are tetracyclines not likely to inhibit protein synthesis in the host?

they are less likely to reach the concentration required for toxicity because eukaryotic cells, in contrast to bacteria, do not have a tetracycline uptake mechanism


Most common use of tetracyclines

treatment of acne


Tetracyclines are the treatment of choice for what kind of infections?

infections caused by chlamydia, Rickettsia, brucellosis, and spirochetal infections
also used to treat anthrax, plague, tularemia, and Legionnaires' disease


Tetracycline is produced by the fermentation of what?

Streptomyces aureofaciens


What side effects does minocycline have that are not shared with other tetracyclines?

vestibular toxicities (vertigo, ataxia, and nausea)


Why is doxycycline considered the tetracycline of choice by many physicians?

it has no potential for 4-epianhydrotetracycline-mediated toxicity and produced fewer GI symptoms