Drug General Information (ID: DDIU4Q0CB6)
  Drug Name Norethisterone Drug Info Mycophenolic acid Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Contraceptive Agents Antiviral Agents
  Structure

 Mechanism of Norethisterone-Mycophenolic acid Interaction (Severity Level: Major)
     Attenuated pharmacological effects (Unspecific) Click to Show/Hide Mechanism Graph
      Drug Name Norethisterone Mycophenolic acid
      Mechanism Hormonal contraceptives Reduce the therapeutic efficacy of hormonal contraceptives
      Key Mechanism Factor 1
Factor Name Pharmacodynamics
Factor Description Reduced pharmacological effects leading to insufficient efficacy and/or treatment failure.
      Mechanism Description
  • Attenuated pharmacological effects of  Norethisterone when combined with Mycophenolic acid 

Recommended Action
      Management Although clinical significance of the interaction is unknown, caution is advised when mycophenolic acid is prescribed in combination with hormonal contraceptives, including all oral, injectable, transdermal, vaginal, and implantable forms. Because use of mycophenolic acid is associated with an increased risk of pregnancy loss in the first trimester and congenital malformations, it is particularly important that female patients not become pregnant during treatment. An acceptable barrier method (e.g., diaphragm with spermicide, cervical cap with spermicide, contraceptive sponge, male condom, female condom) should be used in addition to the hormonal contraceptive of choice during the entire duration of mycophenolic acid therapy and for 6 weeks after discontinuation. Input from a gynecologist or similar expert on adequate contraception should be sought as needed. Intrauterine systems are unlikely to be significantly affected because of their local action.

References
1 Gunston GD, Mehta U "Potentially serious drug interactions with grapefruit juice." S Afr Med J 90 (2000): 41. [PMID: 10721388]
2 Product Information. CellCept (mycophenolate mofetil). Roche Laboratories, Nutley, NJ.
3 Product Information. Myfortic (mycophenolic acid). Novartis Pharmaceuticals, East Hanover, NJ.