Levonorgestrel-Releasing Intrauterine System (Mirena)

1. MIRENA (levonorgestrel-releasing intrauterine system) Health Canada Product Monograph, Bayer Inc.

• Prevention of pregnancy for up to 8 years after insertion.
• Treatment of idiopathic menorrhagia (heavy menstrual bleeding without an identified structural or malignant cause), following appropriate diagnostic investigation, for up to 5 years in women who accept the contraceptive effect of Mirena.

Contraindicated in pregnancy. Confirm pregnancy status and discuss alternative therapy with the prescriber before dispensing.

• Contraindicated in known or suspected pregnancy, since there is no need for pregnancy prevention or menorrhagia treatment in a patient who is already pregnant.
• If pregnancy is confirmed with Mirena in place, rule out ectopic pregnancy first, then remove the system as early as possible, since leaving it in place is associated with a higher risk of miscarriage, infection, and preterm labour/delivery -- removal or uterine manipulation itself can also precipitate miscarriage.

• May be used while breastfeeding; insertion earlier than 4 weeks postpartum is associated with a higher risk of uterine perforation and is generally avoided.
• Small amounts of levonorgestrel pass into breast milk, but no adverse effects on infant growth or development have been established at the low systemic doses released by Mirena.

• Not studied in, and not indicated for, postmenopausal women.

• Safety and efficacy are established in women of reproductive age; not indicated before menarche.
• Use in adolescents should include individualized counselling on insertion comfort and the anticipated irregular bleeding pattern during the first months of use.

• A single Mirena system is inserted into the uterine cavity by a trained healthcare professional under aseptic technique, using the supplied inserter.
• For contraception, Mirena remains effective for up to 8 years; for treatment of idiopathic menorrhagia, the approved duration is up to 5 years, after which a new system should be inserted immediately after removal of the old one if continued treatment is desired.
• Insertion within 7 days of the onset of menses is preferred, though insertion at other times is acceptable once pregnancy has been reasonably excluded; different timing applies immediately postpartum, post-abortion, or when switching from another contraceptive method.
• Confirm placement after insertion (by palpating/visualizing the threads, or by ultrasound if the threads cannot be located) and reassess promptly if the patient cannot feel the threads or expulsion is suspected.
• Counsel before insertion that irregular spotting or light bleeding is very common during the first 3 to 6 months and does not indicate treatment failure -- the full reduction in menstrual blood loss is generally not apparent until bleeding pattern has stabilized, so effect should not be judged before that point.

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

• Not applicable in the usual sense, since the system delivers a continuous local dose rather than being self-administered; no clinically significant systemic overdose scenario has been described with correct placement.

• Irregular bleeding or spotting is very common, especially in the first 3 to 6 months.
• Amenorrhea develops in a substantial proportion of users with continued use.
• Lower abdominal or pelvic pain may occur, particularly around the time of insertion.
• Headache may occur.
• Acne may occur.
• Breast tenderness may occur.
• Ovarian cysts may occur, usually asymptomatic and resolving spontaneously without intervention.
• Vulvovaginitis may occur.
• Mood changes, including depressed mood, may occur.
• Back pain may occur.

Serious side effects require immediate discussion with the prescriber or emergency care.

• Uterine perforation can occur, most often at the time of insertion -- risk is higher during breastfeeding and in a recently postpartum uterus.
• Partial or complete expulsion of the system can occur, more common in the first year of use and in patients with heavy menstrual bleeding; expulsion means loss of both contraceptive and bleeding-control effect.
• Pelvic inflammatory disease risk is highest in the first 20 days after insertion.
• If pregnancy occurs with the system in place, ectopic pregnancy must be considered and excluded.
• The system can become embedded in the myometrium, which may require operative removal.
• Rarely, a perforated system can migrate outside the uterus (including into the abdominal cavity) and require surgical removal.

• History of ectopic pregnancy.
• Conditions with increased susceptibility to pelvic infection (e.g., immunosuppression, IV drug use).
• Coagulopathy or anticoagulant therapy -- increased bleeding risk at the time of insertion or removal.
• Migraine with aura -- systemic hormone exposure from Mirena is low, but individualized risk discussion is reasonable.

• Known or suspected pregnancy.
• Current or recurrent pelvic inflammatory disease, or conditions with increased susceptibility to pelvic infection.
• Postpartum endometritis or infected abortion within the past 3 months.
• Known or suspected malignancy of the uterus or cervix.
• Undiagnosed abnormal uterine bleeding.
• Congenital or acquired uterine anomaly (including fibroids) distorting the uterine cavity in a way that is incompatible with correct insertion/retention.
• Acute liver disease or liver tumour.
• Known or suspected breast cancer or other progestin-sensitive cancer.
• Hypersensitivity to levonorgestrel or any component of the system.

• Because the mechanism is predominantly local (intrauterine) with low systemic levonorgestrel levels, Mirena is not expected to lose contraceptive or bleeding-control efficacy with hepatic enzyme-inducing drugs (e.g., certain anticonvulsants, rifampin) the way systemic hormonal contraceptives can -- this is a key practical advantage over oral hormonal options in patients taking enzyme inducers.

• None significant.

• Not applicable -- inserted and removed by a healthcare professional rather than self-administered on a schedule.

• Store the sterile inserter package at controlled room temperature until the time of insertion; do not use if the sterile packaging has been opened or damaged.

• Expect irregular spotting or light bleeding for the first 3 to 6 months -- this is expected and does not mean the system isn't working; the full reduction in bleeding usually becomes clear only after this settling-in period.
• Learn to check for the removal threads periodically; tell your healthcare professional if the threads feel longer or shorter than before, or if you cannot feel them.
• Seek prompt care for severe pelvic pain, fever, or unusual discharge, especially within the first 3 weeks after insertion.
• Mirena does not protect against sexually transmitted infections.
• The system must be inserted and removed by a healthcare professional -- never attempt removal yourself.