Drugs which are effected by hormonal contraception

The plasma concentration of some drugs may be affected by the concomitant use of hormonal contraceptives.

• drugs which have decreased levels or clinical effects due to hormonal contraceptives are
  • antiepileptics
    • ethinylestradiol may reduce the plasma concentration of lamotrigine monotherapy
  • antihypertensives
  • antidiabetics
    • estrogens and progestogens antagonise the hypoglycaemic effect of antidiabetics
  • diuretics
    • estrogens may antagonise diuretic effect of diuretics
  • thyroid hormones
    • estrogen may increase the thyroid hormone requirements in hypothyroidism
      
      
• drugs which have increased levels or adverse effects due to hormonal contraceptives are
  • antifungals
    • oral contraceptives modestly increase levels of voriconazole
  • anxiolytics and hypnotics
    • estrogens increase plasma concentrations of melatonin
  • bronchodilators
    • estrogens reduce the excretion of theophylline resulting in increased plasma concentrations, a reduction of the theophylline dosage is recommended
  • dopaminergics
    • estrogens increase plasma concentrations of ropinirole
    • estrogens and progestogens increase plasma concentrations of selegiline, with an increased risk of toxicity

Monitoring of drug levels or effect when starting, changing or stopping hormonal contraception may be necessary in women who are on above mentioned drugs that are affected by contraceptive hormones. The woman's hospital doctor and/or general practitioner should be involved in decisions to change contraception and appropriate follow-up should be arranged (1).

Reference:

• 1. Royal College of Obstetricians and Gynaecologists. Faculty of Sexual and Reproductive Healthcare guideline 2011. Drug Interactions with Hormonal Contraceptions