Categories: Drugs/Metabolism

What Antibiotics interfere with OCP?

  1. Rifampin is the antibiotic that is classically stated to be avoided in women taking OCPs

HOW? Rifampin is a potent inducer of cytochrome P450 3A4 and accelerates the elimination of ethinyl estradiol and some progestin components, resulting in an increased risk of OCP failure

OTHER DRUGS TO AVOID: Griseofulvin (an antifungal), Phenytoin, St. John’s Wort and Chronic Alcohol use (can all induce CYP 3A4)

References

1. Barditch-Crovo P, Trapnell CB, Ette E et al (1999) The effects of rifampin and rifabutin on the pharmacokinetics and pharmacodynamics of a combination oral contraceptive. Clin Pharmacol Ther 65:428–438

2. Pelkonen, Olavi et al. Inhibition and induction of human cytochrome P450 enzymes: current status. Arch. Toxicol. October 2008, Volume 82, Issue 10, pp 667-715

Get Medical Pearls directly to your inbox every week!
Weekly posts with high yield medical knowledge, directly to your mailbox!
Dr. C Humphreys

Internal Medicine

Recent Posts

Mechanism of a Mixed Apnea

Mixed apneas are characterized by absent respiratory effort and airflow in the first section of…

12 months ago

How Does Hypothyroidism Cause Hypoventilation?

Although rare, the differential diagnosis of hypoventilation and hypercapnia respiratory failure includes hypothyroidism. It is…

12 months ago

Why is Pro-BNP/ BNP lower in Obesity?

B-type natriuretic peptide (BNP) is a hormone created in response to cardiac wall stretch due…

1 year ago

What is Peribronchovascular Distribution on CT imaging?

A common finding described on computed tomography (CT) imaging. A disease with a peribronchovascular distribution…

2 years ago

Trapped Lung vs. Lung Entrapment

Though often used synonymously; Trapped Lung and Lung Entrapment technically describe separate entities along the…

3 years ago

Cause of Pericardial Effusion in Pulmonary Hypertension: Pathogenesis

It is not clearly understood why patients with pulmonary hypertension (PH) develop pericardial effusions. However,…

3 years ago

This website uses cookies.