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NBME 20 Answers

nbme20/Block 4/Question#29

A 15-year-old girl is brought to the physician by ...

Doxycycline

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 +2  upvote downvote
submitted by breis(11),

Doxycycline is a Tetracycline (binds 30s subunit) and is used off label for treatment of Acne. Can cause discoloration of teeth, and is known to be PHOTOSENSITIVE.

This patient had diffuse erythema and mild edema over her face and extremities, most likely from sun exposure while being on the med for Acne.

FA 2019: pg 192



Tetracyclines most common adverse effects are nausea/vomit/diarrhea and photosensitivity. Can affect bones and teeth of newborn if given to pregnant women. Also this drug class covers GAS, GBS, +/- MRSA, respiratory flora and intracellular.

Why Cipro is not the answer: Macrolide covers GNR + Pseudo, therefore not a treatment for acne (skin flora). And common adverse effects are C.Diff infection, QT prolongation, tendon rupture, teratogenic effects.

+/- lilyo(1),


 +0  upvote downvote
submitted by hayayah(418),

An adverse effect of doxycycline is photosensitivity.

rio19111  Why not Cipro? +1  
raspushok  Which antibiotics increase photosensitivity? Several antibiotic classes commonly cause photosensitivity, including tetracyclines (doxycycline), quinolones (ciprofloxacin, norfloxacin), and sulphonamides (trimethoprim/sulfamethoxazole, sulfasalazine). The tetracycline minocycline is not generally associated with photosensitivity. WHY not damn cipro? +  
medninja  I think it is because Cipro is not commonly used for acne treatment +1  




 +0  upvote downvote
submitted by drdoom(212),

[deleted]





 +0  upvote downvote
submitted by lilyo(1),

Tetracyclines most common adverse effects are nausea/vomit/diarrhea and photosensitivity. Can affect bones and teeth of newborn if given to pregnant women. Also this drug class covers GAS, GBS, +/- MRSA, respiratory flora and intracellular.

Why Cipro is not the answer: Macrolide covers GNR + Pseudo, therefore not a treatment for acne (skin flora). And common adverse effects are C.Diff infection, QT prolongation, tendon rupture, teratogenic effects.