Implants: A modern approach for contraception
Indian Institute of Technology Kanpur
Special thanks to Akanksha Garg
The world population hiked from around 2 billion to 7.2 billion in the past century. In the next couple of decades, this is supposed to cross 9 billion. With the advancement in medical science, life expectancy has skyrocketed in the last few decades. Therefore, contraception is the only strategy to control the population without diluting the satisfaction of intercourse. Most of the contraceptives available in the market are for females. Pills and sterilization are the two extreme methods adopted by women. But these offer serious disadvantages due to the need to maintain regularity in doses and irreversibility, respectively. Thus, smarter, safer, and reversible contraception methods/devices with high efficacy is the need of the hour. Hormone-based Long-acting reversible contraceptives (LARC) which include Intrauterine devices (IUDs) and subdermal contraceptive implants seem to satisfy the major issues of the conventional methods. With an easy-to-use advantage and efficacy of more than 99.9%, contraceptive implants have secured the topmost position in this race, but are they the best we could have?
The first FDA-approved (1990) contraceptive implant Norplant changed our vision towards implantable contraceptives. This was supposed to be inserted in the upper arm under the skin, instead of the vagina or uterus. The device is a set of 6 silicon rods of 34mm length and 2.4mm thickness, containing levonorgestrel—a progestin-only based birth control hormone. The hormone is sustainably released for more than 3 years from the implant by simple diffusion. Progestin helps in thickening the vaginal fluid and prevents sperms from reaching the egg. At high doses, it can also inhibit follicular maturation and thus ovulation. Due to some controversies, Norplant was withdrawn from the market and a 2-rod device Jadelle was launched. Currently, Jadelle and the single rod implant Nexplanon are the most popular subdermal contraceptive implants available in the market. Nexplanon is radiopaque hence easy to detect after implantation.
The unwanted pregnancies in contraceptive implant users are at least 10 times less than IUDs. Although the percentage of discontinuation of implants is not significantly different from IUDs, according to most of the studies, the reason for discontinuation in most of the instances is ‘pain’ in the case of IUDs and ‘bleeding’ in the case of implants. Disturbance in the menstruation cycle is a common side effect of hormonal contraceptives. Although the bleeding pattern, and the extent of bleeding (light or heavy), varies with the type of implant or IUDs used. Interestingly, it also depends on the region of the globe you reside in. According to a study, the women of Southeast Asia have less vaginal bleeding as compared to women from Europe and the United States. Further, unlike barrier contraceptives, the hormonal LARCs may not rescue from sexually transmitted diseases (STD). The sensitivity of the hormones to anti-viral and anti-bacterial STD drugs makes it difficult to deliver both of them (hormone and drug) through a single drug delivery system.
In the modern era, all the social and economic burdens, as well as the burden of parenthood, are expected to be equally divided between couples irrespective of their sex. It should not be a matter of surprise if one suggests introducing male contraceptive implants in society. At the current time, there are only two contraceptive methods available for men: Male condoms (barrier) and vasectomy (sterilization). The former relies on discipline and the availability of condoms at the time of intercourse, while the latter has a poor reversibility rate. A male contraceptive implant MENT®, developed by the researchers at the population council, is under clinical trials. MENT (7α-Methyl-19-nortestosterone) bear a resemblance to testosterone and work by restricting prostate growth. If approved by the regulating bodies, it will be the first long-acting reversible male contraceptive implant.
There is a prime need to develop implants or methods that can minimize side effects. The information mentioned above suggests that sterilization and contraceptive methods are mostly female-biased. The methods should therefore be more women-friendly, easily accessible, and should safeguard the privacy of the individual to avoid hesitation in using them.