A 41-year-old woman with severe inflammatory acne presents with BP 118/76, HR 82, RR 14, Temp 37.2°C. She is prescribed doxycycline 100 mg orally twice daily and currently takes oral contraceptive and a multivitamin with iron and calcium. After 2 weeks, she reports breakthrough bleeding and denies gastrointestinal symptoms. Serum β-hCG is negative. Which mechanism best explains the reduced contraceptive efficacy in this patient?
- A)Doxycycline inhibits estrogen metabolism, reducing hormone levels
- B)Iron and calcium in the multivitamin chelate doxycycline, reducing absorption
- C)Doxycycline disrupts gut flora, impairing enterohepatic circulation of estrogenGABARITO
- D)Doxycycline and estrogen compete for hepatic protein binding
- E)Oral contraceptives induce doxycycline metabolism, reducing antibiotic efficacy
Explicação
Tetracyclines, including doxycycline, can reduce oral contraceptive efficacy by disrupting the gut microbiota. Estrogen is metabolized in the liver, conjugated, excreted in bile, and partially reabsorbed in the intestines via bacterial beta-glucuronidase activ... Ver explicação completa e trilha adaptativa →