Contraceptive implants

 

Contraceptive Implants

For availability pl enquire Infar(originally Organon)

Overview:

     A contraceptive hormone implant is a device that is surgically implanted beneath the skin. An implant is a small flexible plastic rod which is placed just under skin. It releases progestogen hormone over a number of years. There are two different types of implants. Implanon is a single rod implant and Jadelle contain two rods. These two implants are nowadays commonly used. In china and Indonesia however another implant is used called sino Implant – II.

Implanon is a very small thin plastic rod about the size of a big match stick. It is placed just under the skin of one's inner upper arm. It steadily releases a progestogen hormone called etonogestrel into bloodstream. It works for three years continuously.

     Jadelle is a two rod system implant and contain separate progesterone (levonorgestrel). This exerts contractive efficacy for five years.

     Earlier six rod system was need which was popularly known as Norplant. (Six Capsule implant system). This was effective for five years. These are no longer used as its insertion and removal was difficult and more painful to acceptor. Once inserted into a woman’s arm, the implants do not require any action by the user. Since implants do not  contain estrogen,  require any action by the user. Since implants do not contain estrogen, they do not decrease production of breast milk and thus are suitable for breastfeeding women. They are also a good choice for women who do not want more children but are not ready to opt for sterilization, which is a permanent procedure.

     Subdermal contraceptive implants deliver steroidal progestogens from polymer capsules or rods placed under the skin. The hormone diffuses out slowly over a period of 1-5 years and effectively by passes first-pass liver metabolism. Jadelle (first called Norplant-2) was designed to release the same dose of levonorgestrel but from two rods instead of six capsules. There are three other progestogens in implants currently marketed: e.g. etonogestrel (Implanon); Nestorone (Elcometrine) and nomegestrol acetate (Uniplant, surplant).

Table 1: Different Implants

Six Rods:

Norplant (Levonongestrel) –not used nowadays.

Two Rods:

     Jedelle (levonorgestrel)

     Sinoplant II (Levonorgestrel)

Single Rod:

     Implanon – 3 years (etonogestrel)

     Nestorone – 2years (Nestorone)

     Uniplant – 1 year (nomegestrol acetate)

     Both Norplant and Jadelle one made of contain levonorgestrel as the principal hormone but Norplant was used to be marketed as silastic  capsules while present day Jadelle is marketed as ‘Covered Nods’.

 

Implanon

Overview:

     Implanon is a progestogen only contraceptive implant. It consists of a small plastic rod about the size of a matchstick which is inserted just under the skin on the inside of the upper arm. The rod is very flexible and not likely to be visible. The hormone is released slowly from the device into the bloodstream over 3 years.

     It stops the body from releasing an ovum (egg) every month (this is its primary action). Implanon is a single rod implant manufacture by Organon. The rod contains 68mg of progestin called etonogestrel. It exerts contraceptive efficacy for three years. It is registered in over forty counters but not freely available in India.

 

Mode of Action: Inhibits ovulation

    

     Daily release rate of approximately 30ug etonogestrel/day inhibited ovulation in the majority of women. In order to maintain the required release rate of 30ug etonogestrel/day for a projected duration of use of three years, it was found that an initial release rate of about 60ug/day was necessary. Within eight hours after subdermal insertion, etonogestrel levels are sufficient to maintain contraceptive protection for three years.

 

Implanon though inhibits ovulation but endogenous oestrogen (the main female hormone). Is synthesized normally. Therefore, estrogen deficiency symptoms (dry vagina, hot flashes, loss of libido) do not occur neither there is any adverse effects on bone mineral density. Etonogestrel has shown no estrogenic, anti-inflammatory or mineralocorticoid activity, only weak androgenic and anabolic activity, and strong antiestrogenic activity. None of the implants designed until now exhibits a zero order release, and the amount of steroid released per day drops slowly and progressively throughout the months or years of use. Their effective lives extend from 6 to 84 months and in case of implanon it is three years.

 

Ideal Candidate (Candidacy for implanon):

     Suitable for nearly all women. Nearly all women can use implants, including women should have or have not had children; have just had an abortion, miscarriage are breastfeeding (starting as soon as six weeks after child-birth); have anemia; smoke cigarettes (regardless of age).

     Use of implanon for Nursing-Home:     Lactating women need effective contraception at the time of first menses, after starting supplementary feeding, or at 6 months postpartum, whichever comes first. Some may need it earlier because of personal e.g. minipills, quarterly shots and reasons. Contraceptives for nursing women should not affect lactation and should be effective and safe in the evolving physiological and fertility circumstances associated with breastfeeding. It is often considered that non-hormonal methods do not interfere with breastfeeding infant growth and health and should be considered the first choice for lactating women, but they are less effective.