Choosing an Injectable

Injectable contraceptives comprise three progestin-only products given every 2 or 3 months and two monthly combined products. Selection depends on oestrogen eligibility, breastfeeding status, interacting medicines, need for self-care, tolerance of bleeding change and fertility plans.

Comparison.

Combined injectables. Medroxyprogesterone acetate 25 mg with oestradiol cypionate 5 mg, or norethisterone enanthate 50 mg with oestradiol valerate 5 mg, are given every 30 days, up to 7 days early or late. They carry combined-method eligibility rules and are not appropriate where oestrogen is contraindicated.

Mechanism. Progestin-only injectables suppress ovulation and thicken cervical mucus. Return of fertility is delayed for four months or longer after progestin-only injectables.

Selection steps.

1. Confirm the patient wants an injectable and can return on time (or is trained for self-injection).
2. Exclude pregnancy by the usual criteria; test if none applies.
3. Check oestrogen eligibility; if oestrogen is contraindicated, use progestin-only injectables only.
4. Check breastfeeding status: under 6 weeks postpartum is category 3.
5. Check interacting medicines and choose the product accordingly.
6. Check for category 3 and 4 conditions.
7. Counsel on bleeding change, weight, bone density, delayed fertility and condoms.

Category 3 and 4 conditions for progestin-only injectables.

• Breastfeeding under 6 weeks
• severe cirrhosis or liver tumour
• unexplained abnormal bleeding before evaluation
• multiple arterial risk factors
• ischaemic heart disease
• diabetes with vascular disease
• blood pressure 160/100 mm Hg or more
• history of stroke
• acute deep vein thrombosis or pulmonary embolism
• lupus with positive or unknown antiphospholipid antibodies or severe thrombocytopenia (category 3)
• past breast cancer (category 3)
• current breast cancer (category 4)

Category 3 is used only when no other method is available or acceptable, clinical judgement is possible and follow up is assured.

Product choice.

• Need for self-care, limited clinic access or stockout planning: DMPA subcutaneous.
• Long-term rifampicin, rifabutin or enzyme-inducing antiseizure medicine: DMPA (category 1) rather than norethisterone enanthate (category 2).
• Antiretroviral therapy: injectables can be used, including with efavirenz and protease inhibitors; DMPA is effective in these patients.
• Younger than 18 years or older than 45 years: category 2 for progestin-only injectables; do not withhold on age.
• Wanting pregnancy within a year: advise another method, since fertility may be delayed.
• Uncertain ability to return every 8 weeks: prefer a 13-week product or another method.

HIV. Patients at high risk of HIV can use progestin-only injectables (category 2) after counselling that a causal link with HIV acquisition is uncertain; condoms and, where appropriate, pre-exposure prophylaxis can be used with all methods.

Bone. DMPA slightly reduces bone density during use; there is no age or duration limit on use.

Counselling. Consent, confidentiality, absence of coercion, assent for adolescents under 18 years.

Regimens.

• DMPA intramuscular: 150 mg every 13 weeks; DMPA subcutaneous: 104 mg every 13 weeks; norethisterone enanthate: 200 mg every 8 weeks.
• Start within 7 days of menses without backup; later, backup for 7 days.
• Grace window: DMPA up to 4 weeks late; norethisterone enanthate up to 2 weeks late. Over that: exclude pregnancy, inject, backup 7 days.
• Postpartum: breastfeeding women from 6 weeks; non-breastfeeding women at once or within 21 days; later with pregnancy excluded and backup 7 days.
• Switching: from a hormonal method used correctly at once; from another injectable when the repeat injection is due; DMPA and norethisterone enanthate are not interchangeable except at the due date.
• Intrauterine device: start within 7 days of menses and remove then; otherwise keep it until the next menses.

Follow up. Reinjection date given before leaving; review at least yearly for blood pressure, weight, bleeding and satisfaction. Patients who miss an appointment are welcomed back whatever the delay.

Expected effects. Irregular bleeding, heavy or prolonged bleeding, amenorrhoea (most by one year), weight change, headache, dizziness, mood swings, bloating, acne, breast tenderness.

Bleeding management. Exclude gynaecological disease and pregnancy. Give ibuprofen 400 to 800 mg orally three times daily with food for 7 to 14 days, maximum 2400 mg in 24 hours. Avoid it in peptic ulcer, renal impairment, severe liver disease and NSAID-sensitive asthma. Alternatively, give a combined oral contraceptive, one active tablet daily for 1 to 3 cycles, if oestrogen is not contraindicated and the patient is not breastfeeding under 6 months. If unacceptable, stop and change method.

When to change method. Unacceptable bleeding despite treatment, patient wish, fertility plans, new category 3 or 4 condition, or unreliable access to reinjection.

Red flags. Severe lower abdominal pain, severe headache, chest pain, calf swelling, jaundice.

Referral and escalation. Refer unexplained bleeding for examination and cervical screening; refer pregnancy for antenatal care.