What are the dosing schedule, initiation timing, missed‑dose management, contraindications, cautions, drug interactions, common side effects, and alternative contraceptive options for Slynd (drospirenone 4 mg progestin‑only oral contraceptive)?

Slynd (Drospirenone 4 mg Progestin-Only Pill): Clinical Guidance

Slynd is a progestin-only pill containing 4 mg drospirenone taken for 24 consecutive days followed by 4 placebo days, offering effective contraception with a 24-hour missed-pill window and no estrogen-related thrombotic risk, making it ideal for women who cannot use combined hormonal contraceptives. 1, 2

Dosing Schedule & Initiation

• Take one 4 mg drospirenone tablet daily for 24 consecutive days, followed by one placebo tablet daily for 4 days, then immediately start a new pack 1, 2
• Start Slynd on day 1 of menstrual bleeding; no backup contraception is needed if started within the first 5 days of menses 3
• If started after day 5 of the menstrual cycle, use backup contraception (condoms) or abstain from intercourse for the next 2 days 3
• Slynd can be initiated immediately postpartum in breastfeeding women without additional contraceptive protection 3
• For amenorrheic women, start at any time after confirming non-pregnancy; use backup contraception for 2 days 3

Missed-Dose Management

Slynd has a unique 24-hour grace period due to drospirenone's long half-life (30–34 hours), distinguishing it from traditional progestin-only pills that require strict 3-hour timing. 2, 4

• If one pill is missed by <24 hours: Take the missed pill immediately and continue the regular schedule; no backup contraception needed 4
• If one pill is missed by ≥24 hours: Take the most recently missed pill immediately, discard any other missed pills, and use backup contraception for 2 days 3, 4
• Ovulation inhibition is maintained even after four intentional 24-hour delays in pill intake, providing the same flexibility as combined oral contraceptives 4
• If pills are missed during the first week and unprotected intercourse occurred in the previous 5 days, consider emergency contraception 3

Contraceptive Efficacy

• Overall Pearl Index is 0.73 (95% CI 0.31–1.43) based on pooled European data from 14,329 cycles 1
• Pearl Index in Japanese women is 0.39 (95% CI 0.01–2.18) over 3,319 cycles 5
• U.S. data show a Pearl Index of 4.0, though European Union data demonstrate 0.93 6
• Efficacy approaches that of combined oral contraceptives while avoiding estrogen-related risks 1, 2

Absolute Contraindications

• Current or history of breast cancer or other hormone-sensitive malignancies 3, 7
• Severe uncontrolled hypertension (systolic ≥160 mmHg or diastolic ≥100 mmHg) 3, 8
• Active or severe liver disease, including hepatitis, cirrhosis, or hepatic tumors 3, 7
• Pregnancy 3, 7
• Undiagnosed abnormal uterine bleeding 3, 7
• Adrenal insufficiency (drospirenone's antimineralocorticoid activity may worsen this condition) 3
• Renal impairment (risk of hyperkalemia) 3

Unlike combined hormonal contraceptives, Slynd is NOT contraindicated in women with history of venous thromboembolism, smoking at any age, migraine with aura, or cardiovascular disease, because it contains no estrogen. 1, 5, 2

Cautions & Monitoring

Hyperkalemia Risk

• Check serum potassium during the first treatment cycle in women taking potassium-increasing medications: ACE inhibitors, angiotensin II receptor blockers, potassium-sparing diuretics, NSAIDs, or heparin 3, 7
• Large retrospective studies show no increased hyperkalemia risk in healthy women, even when combined with spironolactone 7
• Routine potassium monitoring is unnecessary in women without risk factors 7

Blood Pressure Effects

• Drospirenone's antimineralocorticoid activity typically lowers systolic blood pressure by 1–4 mmHg 3, 7
• In women with baseline systolic BP ≥130 mmHg, drospirenone 4 mg reduces systolic BP by approximately 8 mmHg and diastolic BP by 5 mmHg 3, 7
• Measure blood pressure at baseline and follow-up visits 3, 7

Cardiovascular Safety

• No cases of deep vein thrombosis or pulmonary embolism were reported in the pivotal trials of 1,571 women over 14,329 cycles 1
• Progestin-only pills do not increase risk of venous thromboembolism, stroke, or myocardial infarction 1
• This represents a major safety advantage over combined hormonal contraceptives containing drospirenone, which carry a 50–80% higher VTE risk than levonorgestrel-containing pills 7

Drug Interactions

• Strong CYP3A4 inducers (rifampin, griseofulvin, carbamazepine, phenytoin, St. John's wort) may reduce contraceptive effectiveness; use backup contraception 3
• Tetracycline-class antibiotics do NOT reduce contraceptive effectiveness and are safe to co-administer 8
• Medications that increase serum potassium (ACE inhibitors, ARBs, potassium-sparing diuretics, NSAIDs, heparin) require potassium monitoring when used with Slynd 3, 7
• Avoid concurrent use with tranexamic acid due to theoretical increased thrombotic risk 3

Common Side Effects

• Unscheduled bleeding (breakthrough bleeding or spotting) occurs in 89.5–91.6% of users, representing the most common adverse effect 5, 6
• Intermenstrual bleeding is most frequent during the first 2–3 cycles and typically resolves spontaneously 7
• Scheduled withdrawal bleeding rates are low compared to combined hormonal contraceptives 6
• Other common side effects include nausea, headache, and breast tenderness, which usually resolve within the first 2–3 cycles 7
• Only one case of hyperkalemia was reported in the pivotal trials 1
• All treatment-emergent adverse events in clinical trials were mild or moderate; no severe events occurred 5

Management of Breakthrough Bleeding

• Reassure patients that unscheduled bleeding typically resolves within 2–3 cycles 7, 9
• Verify strict adherence to the dosing schedule, as missed pills are the primary cause of persistent bleeding 9
• If bleeding persists beyond 3 cycles, rule out pregnancy, sexually transmitted infections, cervical pathology, and drug interactions before switching methods 9
• If no underlying pathology is identified and bleeding remains unacceptable, consider switching to a levonorgestrel intrauterine device or estetrol 15 mg/drospirenone 3 mg combined oral contraceptive, which provides regular scheduled bleeding patterns 9, 6

Alternative Contraceptive Options

For Women Who Cannot Tolerate Breakthrough Bleeding

• Estetrol 15 mg/drospirenone 3 mg combined oral contraceptive offers a predictable bleeding profile with high rates of scheduled bleeding and low rates of unscheduled bleeding 6
• Levonorgestrel intrauterine device provides excellent contraceptive efficacy with eventual amenorrhea in most users, though initial irregular bleeding is common 9

For Women With VTE Risk Factors

• Slynd is already the preferred option, as it carries no estrogen-related thrombotic risk 1, 5
• Other progestin-only methods include norethindrone 0.35 mg (requires strict 3-hour timing), etonogestrel implant, or levonorgestrel intrauterine device 3

For Women Requiring Blood Pressure Reduction

• Slynd is an excellent choice due to drospirenone's antimineralocorticoid activity, which lowers blood pressure 3, 7

Patient Counseling

• Emphasize that Slynd offers a 24-hour missed-pill window, unlike traditional progestin-only pills that require strict 3-hour timing 2, 4
• Warn that unscheduled bleeding is very common (>90% of users) but typically improves after 2–3 cycles 5, 6
• Advise taking the tablet at the same time each day using reminders (phone alarms, support from family/partner) 8
• For nausea, recommend taking the tablet with food or at bedtime; symptoms usually resolve within the first few cycles 7, 8
• Prescribe up to a 1-year supply to improve continuation rates 8
• Instruct patients to use backup contraception for 2 days if a pill is missed by ≥24 hours 3, 4
• Explain that seven consecutive active pills are required to reliably suppress ovulation 8

Baseline Assessment

• Obtain a comprehensive medical history focusing on contraindications: liver disease, renal impairment, adrenal insufficiency, uncontrolled hypertension, hormone-sensitive cancers 3, 7
• Measure blood pressure 3, 7
• Confirm non-pregnant status 3, 8
• Pelvic examination and Pap smear are no longer mandatory before prescribing 8
• Check serum potassium only if the patient takes potassium-increasing medications 3, 7

Ongoing Monitoring

• Schedule a follow-up visit 1–3 months after initiation to address adverse effects and adherence 8
• Re-measure blood pressure at each follow-up visit 3, 7, 9
• Assess bleeding patterns every 3 months 9
• If breakthrough bleeding persists beyond 3 cycles, evaluate for pregnancy, sexually transmitted infections, cervical pathology, and drug interactions 9

Special Populations

Breastfeeding Women

• Slynd can be initiated immediately postpartum in breastfeeding women 3
• The World Health Organization recommends avoiding combined hormonal contraceptives when possible due to potential reduction in milk production, but progestin-only pills are acceptable 3, 8

Women With Cardiovascular Risk Factors

• Slynd is the preferred oral contraceptive for women with history of VTE, stroke, myocardial infarction, migraine with aura, or smoking at any age, because it contains no estrogen 1, 5, 2
• No increased cardiovascular risk has been demonstrated in clinical trials 1, 5

Women With Hypertension

• Slynd may lower blood pressure and is not contraindicated in women with controlled hypertension 3, 7
• Avoid in women with severe uncontrolled hypertension (systolic ≥160 mmHg or diastolic ≥100 mmHg) 3, 8