[For norethisterone contraceptive see Progesterone Only Contraceptive monograph]
Issues for Surgery
For treatment of endometriosis, menorrhagia or dysfunctional uterine bleeding – potential increase in symptoms if stopped.
Risk of venous thromboembolism (VTE) if therapeutic doses continued1 (see Further Information).
Advice in the Perioperative period
Consider stopping 4-6 weeks before surgery where prolonged immobilisation is likely (e.g. abdominal surgery or orthopaedic lower limb surgery)2.
If continuing, ensure adequate thromboprophylaxis as risk of VTE comparable to combined oral contraceptive pill2.
Ensure adequate thromboprophylaxis as risk of VTE comparable to combined oral contraceptive pill2.
Consider stopping on admission if prolonged immobilisation is likely2.
If discontinued pre-operatively, restart once mobile.
Interaction(s) with Common Anaesthetic Agents
Administration of a single bolus dose of sugammadex is predicted to cause a 34% decrease in progestogen exposure3, 4.
Interaction(s) with other Common Medicines used in the Perioperative Period
Risk of VTE
Therapeutic doses of norethisterone and norethisterone acetate (used for endometriosis, menorrhagia, dysfunctional uterine bleeding or postponement of menstruation1) are thought to be associated with an increased risk of VTE. Partial metabolism of norethisterone to ethinylestradiol has been noted at doses exceeding 5mg5. A daily norethisterone dose of 10-20mg is likely to equate to a 20-30microgram dose of ethinylestradiol, and therefore carry the same VTE risk as the combined contraceptive pill6.
The conversion of norethisterone to ethinylestradiol has been attributed to a structural peculiarity of the norethisterone molecule and thus there are no implications for other progestogens regardless of dose6.