A 19-year-old woman presents to the emergency department with fever (39.4°C), severe headache, neck stiffness, and photophobia. Vital signs show BP 116/74, HR 105, RR 22, SpO2 99% on room air. Blood cultures and CSF analysis are pending. She is currently taking an oral contraceptive (ethinyl estradiol/levonorgestrel) with perfect adherence. Empiric treatment for bacterial meningitis is initiated with ceftriaxone, vancomycin, and rifampin. CSF results confirm Neisseria meningitidis sensitive to all agents. Two weeks later, her contraceptive method fails despite continued perfect adherence and no missed doses. Which of the following best explains the contraceptive failure in this patient?
- A)Rifampin induces hepatic CYP3A4 and other cytochrome P450 enzymes, increasing first-pass metabolism of ethinyl estradiolGABARITO
- B)Ceftriaxone disrupts intestinal flora and reduces enterohepatic circulation of estrogen metabolites
- C)Vancomycin inhibits hepatic metabolism of oral contraceptive hormones, paradoxically reducing serum levels
- D)Rifampin competitively inhibits intestinal absorption of oral contraceptive pills in the duodenum
- E)The combination of three antibiotics creates a synergistic effect that directly inactivates ethinyl estradiol in the gastrointestinal tract
Explicação
Rifampin is a potent inducer of multiple hepatic cytochrome P450 enzymes, including CYP3A4, which metabolizes ethinyl estradiol and progestins. This increased metabolism accelerates drug clearance, reduces serum hormone concentrations below therapeutic levels,... Ver explicação completa e trilha adaptativa →