Electronic monitor, transdermal patches may be available by year 2000
October 1, 1997
Electronic monitor, transdermal patches may be available by year 2000
2 contraceptive options are on the cutting edge
What will women be using for birth control in the not-so-distant future? They may be able to use an electronic monitor to naturally gauge their fertility cycles for "safe" days for sex, or they could wear a transdermal patch with a new progestin for birth control. Or they could suggest their partners investigate a similar skin patch using a different type of synthetic hormone for male contraception.
Sano Corp., based in Miramar, FL, has negotiated an exclusive license with the New York City-based Population Council for the North American rights to use the Council’s progestin, Nesterone, in transdermal patches for female contraception and hormone replacement therapy. The agreement also allows Sano to secure the exclusive, worldwide rights for the transdermal use of the Population Council’s patented, synthetic androgen, 7-alpha methyl-19-nortestosterone (MENT), for male contraception and treatment of hypogonadism (testosterone deficiency).
Unilever of London has established Unipath Diagnostics Company in New York City to provide a local base for the potential launch of the Unipath contraceptive system. Enrollment for the clinical trial of the method, now marketed in the United Kingdom, Ireland, and Italy under the Persona brand name, is under way in seven U.S. cities, reports Janet Jacobs, FIBF, Unipath Diagnostic’s director of clinical research.
Low dose ideal for transdermal use
Sano, with experience in controlled-release drug delivery systems, sees unique opportunities with the two Population Council-developed synthetic hormones, says company president Reginald Hardy. "Nesterone has a very clean profile, meaning that it has significant advantages over what we see with norethindrone acetate," which is another progestin found in several combined oral contraceptives, he explains. "For transdermal delivery, a therapeutic dose for contraception with Nesterone is going to be somewhere in the 25 to 100 mcg range, which is a very small amount of drug."
Sano did have an estradiol/norethindrone acetate patch under development but decided to pursue Nesterone instead due to its enhanced capabilities, Hardy says. The company plans to file an investigational new drug application with the U.S. Food and Drug Administration early in 1998 and move toward a new drug application within two to three years, Hardy says.
Previously known as ST-1435, Nesterone is readily absorbed through the skin into the bloodstream. This would make it a good choice for breast-feeding mothers, since it would not be readily absorbed into an infant’s system through breast milk.1 It also does not appear to disrupt carbohydrate or lipid metabolism.2
In a two-year clinical trial using Nesterone in a single-rod subdermal implant, researchers reported no pregnancies among those using the method.3 The implants were well-tolerated, with irregular bleeding the most common side effect.
The Population Council continues to work with the progestin in a number of forms for contraceptive use, says Harold Nash, PhD, senior scientist. It also reports that clinics in Europe, Latin America, and the United States are comparing three dosage ratios of the Nesterone/EE ring, as well as a combination with a regimen of 26 days in and four out.4
"We have worked with Nesterone for several years and have fairly extensive testing of implants through Phase II as contraceptives in females," he says. "We are conducting testing on Nesterone and a combination with an estrogen, ethinyl estradiol, as a contraceptive, as contrasted with implants."
While the body of research on MENT is not as developed as that for Nesterone, Hardy says the synthetic androgen promises many potential uses. (See Contraceptive Technology Update, August 1995, p. 96, for review of research on the Population Council’s use of a two-rod implant using MENT and a GnRH analog.)
"MENT is of high potency and, therefore, it might be given in a sustained release dosage form, such as an implant, and still accomplish its mission, either supporting secondary sex function or at somewhat higher doses be a contraceptive in men in itself," Nash says.
"Furthermore, of particular importance, it is not metabolized in the same way as is testosterone and therefore is not expected to stimulate the prostate in the same way as does testosterone, and that’s true in animal experiments."
The Unipath system relies upon use of a small electronic monitor, initialized the first day after a woman’s menstrual cycle begins, Jacobs explains. Each morning thereafter, the monitor will display one of three lights: green, indicating no risk for pregnancy and no need for a contraceptive; red, indicating risk of pregnancy and need for abstention from sex (a requirement during the trial in actual use, couples may use a barrier method); and yellow, prompting the woman to perform a simple urine test. After the monitor analyzes the test, it will flash a red or green light to indicate whether there is a risk of pregnancy that day.
The monitor’s computer memory stores the information from the woman’s six most recent cycles, so during the first few months of use, it shows more red lights, Jacobs explains. As it builds up more of a picture about the woman’s fertility cycle, it individualizes the information, and the number of red lights are reduced.
European efficacy trials, conducted in multiple centers in the United Kingdom and Germany, showed that the method was 94% reliable in preventing pregnancy, Jacobs says.
The technology for the Unipath system is similar to other products developed by Unipath, ClearBlue Easy and ClearPlan Easy. These devices analyze only one hormone; the Unipath system accesses two so it can identify the beginning and end of the fertile period, Jacobs says.
While it is too early to project costs for the American system, the start-up kit, which contains the monitor and strips for 16 urine tests, retails in Britain for £49.95 (about $85 U.S.), says Jacobs. Boxes of eight test strips retail at £9.95 (about $17).
"It’s an objective method, rather than a subjective interpretation, which many people either find difficult or just too time-consuming," she observes. "We found that with people actually using it, the people go to it for birth control, then suddenly the added information increases the value of the system to them. It’s giving them the information about when you’re about to ovulate, which is a very encouraging thing to women who perhaps had concerns about their fertility after using birth control for many years."
References
1. Blaney CL. New approaches seek greater safety, appeal. Network 1995; 15:27.
2. Odlind V, Lithell H, Selinus I, et al. Unaltered lipoprotein and carbohydrate metabolism during treatment with contraceptive subdermal implants containing ST-1435. Contraception 1985; 31:123-130.
3. Díaz S, Schiappacasse V, Pavez M, et al. Clinical trials with Nesterone subdermal contraceptive implants. Contraception 1995; 51:33-38.
4. Population Council. Contraceptive rings provide simple protection. Population Briefs 1997; 3:4.
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