Introduction
Drospirenone is a synthetic progestin commonly found in the popular oral contraceptive, Yaz in combination with Ethinyl estradiol. Most recently, it was approved by both Health Canada and the FDA in combination with Estetrol as an oral contraceptive therapy. Aside from its contraceptive effects, drospirenone is used with estrogens to control acne and premenstrual dysphoric disorder (PMDD).
Drospirenone has been the subject of widespread safety concern due to the possibility of an increased risk of venous thromboembolism associated with its use. In 2012, however, a safety statement by the FDA concluded that the increase in the risk of thromboembolism resulting from the use of drospirenone remains unclear, as studies regarding this risk are conflicting. Some studies have demonstrated a significantly increased risk and some demonstrating no risk of thromboembolic events. In its statement, the FDA has mentioned that increased risk of venous thromboembolism with oral contraceptives such as drospirenone exists but remains lower than the risk of this condition during pregnancy and during the postpartum period, and this should be considered when assessing potential risks of hormonal contraceptive use.
Uses
Drospirenone is a progestin used in oral contraceptive pills for the prevention of pregnancy and other conditions.
Drospirenone, in combination with ethinyl estradiol or estetrol, is indicated as an oral contraceptive for the prevention of pregnancy. In addition to its use for contraceptive effects, this combination is used to treat moderate acne vulgaris and the symptoms of premenstrual dysphoric disorder. The drug has approved indications for combination with estrogens for the treatment of menopause-associated symptoms, such as vasomotor symptoms and vulvovaginal atrophy. Drospirenone combined with estrogen may also may aid in the prevention of osteoporosis in women who have been post-menopausal for at least a year and are not candidates for other therapies. It can sometimes be found in preparations containing estrogen and folic acid for folic acid replenishment during oral contraception.
When used for the treatment of acne vulgaris, drospirenone-containing contraceptives should only be used in women ≥14 years of age who have experienced menarche, desire oral contraception, and do not have any contraindications to oral contraceptives. Off-label uses for this drug include the treatment of menstrual irregularities, dysmenorrhea, hirsutism, and endometriosis.
Associated Conditions
Pharmacodynamics
Drospirenone inhibits the maturation of follicles and inhibits ovulation, preventing pregnancy. It has antiandrogen effects, improving acne and hirsutism. When combined with ethinyl estradiol, it has been shown to have favorable effects on the plasma lipid profile. Due to its similarity to naturally occurring progesterone, drospirenone is thought to be associated with a lower incidence of progesterone contraceptive related adverse effects, such as breast tenderness and mood swings.
A note on venous thromboembolism risk and antimineralcorticoid effects
As with other oral contraceptives, the risk of venous thromboembolism and cardiovascular events may be increased when drospirenone is taken. The risk is especially higher in smokers and women aged 35 and older. Women taking this drug should be advised not to smoke. In addition, drospirenone, due to its antimineralcorticoid effects, may increase the risk of hyperkalemia. Patients at high risk for hyperkalemia should not be administered this drug. Consult the official prescribing information for detailed and updated information on the cardiovascular and other risks associated with drospirenone use.
Mechanism of Action
Drospirenone and ethinyl estradiol in combination suppress the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH), preventing ovulation. Other changes induced by this drug which may aid in the prevention of pregnancy include alterations in cervical mucus consistency, hindering sperm movement, and lowering the chance of embryo implantation.
Drospirenone is an analog of the diuretic spironolactone, which exerts anti-mineralocorticoid activity, blocking aldosterone receptors, which increases sodium and water excretion. Studies in animals have demonstrated that drospirenone administration leads to antiandrogenic activity. This activity helps to oppose the effects of naturally occurring androgens, inhibiting the binding of dihydrotestosterone (DHT) to its receptor, and preventing androgen synthesis in the ovaries, helping to treat acne and hirsutism. Drospirenone may also decrease the level of edema in sebaceous follicle during the second half of the menstrual cycle, when acne often appears.
Absorption
The absolute bioavailability of drospirenone is approximately 76% due to first-pass effects. The maximum plasma concentration of drospirenone occurs within 1 to 2 hours after oral administration and is estimated to range between 60 and 87 ng/mL. A European prescribing monograph for the combination product of estradiol and drospirenone indicates that drospirenone is both completely and rapidly absorbed. It reports a Cmax of 21.9 ng/ml, achieved approximately 1-hour post-administration. The absolute bioavailability is reported to range between 76 to 85%.
Volume of Distribution
The volume of distribution of drospirenone is estimated to be 4 L/kg, according to the FDA label for Yaz. Prescribing information from a combination of estradiol and drospirenone estimates the volume of distribution to range from 3.7- 4.2 L/kg.
Protein Binding
Drospirenone is about 95% to 97% bound to serum plasma protein, likely to albumin. During in vitro studies, drospirenone was found to bind with low affinity to sex hormone-binding globulin (SHBG). Another reference indicates that drospirenone binds to serum albumin but does not bind to sex hormone-binding globulin (SHBG), nor corticoid binding globulin (CBG). Only 3-5% of the total drospirenone concentration is measured as a free steroid.
Route of Elimination
Various metabolites of drospirenone are measured in the urine and feces. Drospirenone elimination from the body is almost after 10 days post-administration when negligible amounts of drospirenone are found unchanged in both the urine and feces. Between 38% to 47% of the metabolites are identified as glucuronide and sulfate conjugates in the urine. In the feces, approximately 17% to 20% of identifiable metabolites are found to be excreted as glucuronides and sulfates.
Half Life
The serum half-life of drospirenone is estimated to be 30 hours. The half-life of drospirenone metabolite excretion in the urine and feces is approximately 40 hours.
Clearance
Drospirenone is rapidly cleared, typically within 2-3 days of administration of the last active tablet. The rate of clearance of drospirenone calculated in the serum ranges from 1.2-1.5 ml/min/kg, however, this value can vary by up to 25% according to the patient.
Toxicity
The oral LD50 of drospirenone in rats is >2000 mg/kg.
Overdose information An overdose of drospirenone, like other oral contraceptives, may lead to cause nausea or withdrawal bleeding. For drospirenone in particular, as an analog of spironolactone, may affect the levels of serum sodium and potassium. Their concentrations should be monitored in cases of overdose in addition to monitoring from metabolic acidosis and hyperkalemia, which may also result.
Food Interactions
- Avoid St. John's Wort.
- Take at the same time every day.
- Take with or without food.
Dosage
Instructions for starting of Drospirenone: Starting in females with no current use of hormonal contraception (Day 1 Start) Important: Consider the possibility of ovulation and conception prior to initiation of this product. Tablet Color: Drospirenone active tablets are white (Day 1 to Day 24). Drospirenone inert tablets are light pink (Day 25 to Day 28).
Day 1 Start :
- Take the first white active tablet on the first day of menses.
- Take subsequent white active tablets once daily at the same time each day for a total of 24 days.
- Take one light pink inert tablet daily for 4 days and at time of day that active tablets were taken.
- Begin each subsequent pack on the same day of the week as the first cycle pack (i.e., on the day after taking the last inactive tablet).
- Switching from another contraceptive method to Drospirenone: Start Drospirenone.
- A Combined Oral Contraceptive (COC): On the day when the new pack of the previous COC would have started.
- Transdermal Patch: On the day when next application would have been scheduled.
- Vaginal ring: On the day when next insertion would have been scheduled.
- Injection: On the day when next injection would have been scheduled.
- Intrauterine contraceptive: On the day of removal.
- Implant: On the day of removal.
