A 22-year-old woman is evaluated in the office due to progressive acne on her face, chest and back. Although, she takes oral doxycyclin regularly, her acne has worsened over last month. The patient was recently diagnosed with iron deficiency anemia due to abnormal uterine bleeding and began taking a combined oral contraceptive and an iron supplement. Physical examination shows comedones and pustules on her face and upper back. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of this patient's worsening symptoms?

Question

A 22-year-old woman is evaluated in the office due to progressive acne on her face, chest and back. Although, she takes oral doxycyclin regularly, her acne has worsened over last month. The patient was recently diagnosed with iron deficiency anemia due to abnormal uterine bleeding and began taking a combined oral contraceptive and an iron supplement.  Physical examination shows comedones and pustules on her face and upper back.  The remainder of the examination shows no abnormalities.  Which of the following is the most likely cause of this patient's worsening symptoms?

Quizplus · Accepted Answer

Eductional Objective: Tetracyclines interact with polyvalent cations (eg, iron, calcium, aluminum, magnesium) to form nonabsorbable chelate complexes in the gastrointestinal tract.  This can lead to significantly decreased drug absorption and therapeutic effect.  Fluoroquinolones and thyroxine are also susceptible to chelation.

A 22-Year-Old Woman Is Evaluated in the Office Due to Progressive