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New oral contraceptive claims to reduce some common side effects

By mid-June, there will be yet another oral contraceptive on your pharmacy shelf. Yasmin, marketed by Berlex Laboratories, Montville, NJ, differs from the crowd, though. Along with 0.03 mg ethinyl estradiol, it contains 3 mg drospirenone, a novel progestin that is an analog of spironolactone.

This low-dose contraceptive has demonstrated safety and effectiveness in clinical trials and is approved by the Food & Drug Administration for prevention of pregnancy. "This novel progestin may offer advantages," said Marie Foegh, M.D., medical director, clinical research and development, female health care, Berlex. Many currently marketed oral contraceptives, she said, are associated with headache, nausea, and emotional lability, side effects believed to be associated with the progestin component and water and electrolyte retention.

"Like spironolactone, drospirenone causes sodium and water excretion and potassium reabsorption," noted Candace Brown, Pharm.D., MSN, professor in pharmacy practice, ob-gyn and psychiatry, University of Tennessee. Brown, who has been involved in ethinyl estradiol/drospirenone clinical trials, found that women taking the combination reported less breast tenderness and abdominal bloating compared with their baseline symptoms. And while they did not report a decrease in weight, neither did they report an increase.

Drospirenone may also have a beneficial effect on some mood symptoms, noted Brown. "Drospirenone is different [from other progestins] because it decreases testosterone by two methods" instead of one. It indirectly decreases the synthesis of testosterone from the adrenal glands and the ovaries, and it decreases the synthesis of testosterone from areas of the skin. "Some studies have shown that increased testosterone is related to irritability," Brown said, "and we did find this to be true."

Studies have been limited to women who do not have severe premenstrual syndrome (PMS), but "what we're now looking at is women who have severe PMS," Brown commented.

While drospirenone offers potential benefits to some women, its properties limit its use in others. As an analog of spironolactone, it can increase potassium levels. Thus it is contraindicated in women with renal insufficiency, hepatic dysfunction, or adrenal insufficiency. And women who are taking medications that increase potassium levels—specifically, ACE inhibitors, angiotensin-II receptor antagonists, potassium-sparing diuretics, heparin, aldosterone antagonists, and non-steroidal anti-inflammatory drugs—should have their potassium levels checked during the first treatment cycle. The ethinyl estradiol/drospirenone combo also carries the contraindications of the other currently marketed oral contraceptives.

According to the package insert, the most common adverse events, occurring at a rate greater than 1%, include headache, menstrual disorder, breast pain, and abdominal pain and emotional lability. But until head-to-head trials are performed, it will not be known how the incidence of side effects compares with that of other oral contraceptives. What is known is that in one large trial evaluating dose, the new drug had a discontinuation rate of 6% due to side effects, compared with the 6.6%-50% rate found in the literature of already marketed oral contraceptives.

Side effects of oral contraceptives are becoming a major reason women discontinue these drugs. A National Women's Health Resource Center (NWHRC) study of oral contraceptive use in women between 18 and 45 years of age found that 47% of women surveyed were dissatisfied enough with side effects to discontinue use or switch to another brand of oral contraceptives over the past five years.

"The significance of the discontinuation rate pertains to unintended pregnancies. In the United States, there are about 700,000 unintended pregnancies every year because women are discontinuing their birth control pills. That translates to about $2.6 billion annually. So it is not only a personal issue, it translates into a public health issue," said Amy Nile, executive director, NWHRC.

Kathy Hitchens, Pharm.D.

The author is a medical writer based in Indianapolis.

TIPS TO REMEMBER: Yasmin

• Yasmin can increase potassium levels. Thus, it is contraindicated in women with renal insufficiency, hepatic dysfunction, or adrenal insufficiency.

• Women taking medications that increase potassium levels should have their potassium level checked during the first treatment cycle.

 

Kathy Hitchens. New oral contraceptive offers women novel ingredient. Drug Topics 2001;11:13.