Low-dose modified-release doxycycline (40 mg daily) is effective in papulopustular rosacea even though the dose is below its minimum inhibitory concentration against bacteria. This efficacy is explained by which property of doxycycline?
- A Inhibition of matrix metalloproteinases and neutrophil chemotaxis ✓
- B Selective suppression of Cutibacterium acnes biofilm
- C Vasoconstriction of dermal blood vessels via alpha agonism
- D Blockade of transient receptor potential channels
Correct answer: A. Inhibition of matrix metalloproteinases and neutrophil chemotaxis
Explanation
Subantimicrobial-dose doxycycline acts as an anti-inflammatory agent by inhibiting matrix metalloproteinases, reactive oxygen species generation and neutrophil chemotaxis, all of which drive rosacea inflammation. This allows benefit without altering cutaneous microbiota and minimises antibiotic resistance. Brimonidine provides alpha-adrenergic vasoconstriction for erythema, and ivermectin targets Demodex, so options C and D describe other drugs' mechanisms entirely.
Reference: Bolognia Dermatology, 5th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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