Desogestrel Pill

Desogestrel progestin-only pills contain desogestrel 75 microgram in each tablet, taken daily without a pill-free interval. Desogestrel is a prodrug converted to etonogestrel. Unlike traditional low-dose pills, it suppresses ovulation consistently, so the late-tablet window is 12 hours rather than 3 hours.

Mechanism. Ovulation suppression, thickened cervical mucus and a thin endometrium. About 48 hours of use is needed for the mucus effect.

Pharmacokinetics. Desogestrel is rapidly converted to etonogestrel, which has an elimination half-life of about 30 hours.

Effectiveness. Pill class estimates apply: typical use 9 and perfect use 0.3 pregnancies in 100 women in the first year.

Return to fertility. Rapid, with normal ovulation after stopping.

Ideal candidates. Patients who need an oestrogen-free pill, breastfeeding women from 4 weeks postpartum, and patients whose timing may vary by several hours.

Assessment. Medicine, menstrual and breastfeeding history, and blood pressure. No routine pelvic or breast examination or laboratory test is needed. Exclude pregnancy by the usual criteria, with a test if none applies.

Eligibility. The pill categories apply.

• Category 3: current rifampicin or rifabutin; phenytoin, carbamazepine, barbiturates, primidone, topiramate, oxcarbazepine; acute deep vein thrombosis or pulmonary embolism; severe decompensated cirrhosis or liver tumour; lupus with positive or unknown antiphospholipid antibodies; past breast cancer.
• Category 4: current breast cancer.
• Category 2: breastfeeding under 4 weeks; antiretroviral therapy with efavirenz, nevirapine or ritonavir-boosted regimens; past ectopic pregnancy; ischaemic heart disease or stroke; unexplained bleeding before evaluation.
• Category 1: obesity, smoking, hypertension that can be measured and is controlled, HIV, sickle cell disease, migraine without aura.

Interactions. Enzyme inducers lower etonogestrel levels: rifampicin, rifabutin, antiseizure inducers, efavirenz, ritonavir-boosted regimens, griseofulvin, St John’s wort. For short courses, add condoms during treatment and for 28 days after. For long-term use choose DMPA or an intrauterine device.

Counselling. Consent, confidentiality, absence of coercion, and condoms for infection protection. Adolescents under 18 years give assent. Warn that bleeding is unpredictable and amenorrhoea is common.

Regimen.

• Desogestrel 75 microgram tablet, orally, one tablet daily at the same time, no break between packs.
• Start on days 1 to 5 of menses without backup; later starts need backup for 2 days.
• Grace window: 12 hours. A tablet more than 12 hours late is a missed tablet.
• Backup after a missed tablet: condoms or abstinence for 2 days.
• Switching from a hormonal method used correctly: start at once without overlap.
• No dose change for body weight.

Start timing. Postpartum, breastfeeding women start from 4 weeks. Non-breastfeeding women start at once or within 3 weeks; after 3 weeks without menses exclude pregnancy and use backup for 2 days. After abortion start at once. From an injectable start when the repeat injection is due. From an intrauterine device start in the first 5 days of menses and remove the device then, or keep it until the next menses.

Late or missed tablets.

• Less than 12 hours late: take it, continue, no backup.
• Over 12 hours late: take the missed tablet at once, continue daily, use backup for 2 days, and consider emergency contraception if she had unprotected sex in the last 5 days.
• Vomiting within 2 hours: take another tablet. Severe vomiting or diarrhoea over 2 days: count each day as missed and use backup for 2 days after recovery.

Follow up. Review for bleeding concerns and at least once a year. Perimenopausal patients may continue; stopping is considered at about 55 years.

Expected effects. Irregular, frequent, prolonged or absent bleeding; acne; headache; mood change; breast tenderness; weight change. These are not harmful.

Management.

• Troublesome bleeding: exclude pregnancy, interacting medicines and gynaecological disease. Give ibuprofen 400 to 800 mg orally three times daily with food for 7 to 14 days, maximum 2400 mg in 24 hours (avoid in peptic ulcer, renal impairment, severe liver disease, NSAID-sensitive asthma). Add a combined oral contraceptive, one active tablet daily for 1 to 3 cycles, if oestrogen is not contraindicated and not breastfeeding under 6 months.
• Persistent unacceptable bleeding: stop and offer another method.
• Amenorrhoea: reassure; test for pregnancy if tablets were missed.
• Worsening headache or migraine with aura: stop and change method.

Complications. Functional ovarian cysts usually resolve alone. If pregnancy occurs, exclude ectopic pregnancy.

Red flags. Severe lower abdominal pain, calf swelling, chest pain, jaundice, breast lump.

Referral and escalation. Refer unexplained bleeding for pelvic examination and cervical screening where available.