Levonorgestrel (LNG) is a synthetic steroid analogue used in a number of birth control methods. Levonorgestrel was first made in the 1960s and has been used as a method of birth control since the 1980s. Today it is on the World Health Organization’s List of Essential Medicines, the most important medications needed in a basic health system, and is available as a generic medication. In pill form, sold under the brand name “Plan B” among others, LNG can be used as an emergency birth control when taken within 120 hours. LNG may also be combined with an estrogen to make an oral contraceptive, or used alone as the mini-pill. As part of an LNG-releasing IUD, sold as Mirena among others, it is effective for long-term prevention of pregnancy. An implantable form of levonorgestrel, Norplant, is available in some countries. LNG works as a contraceptive by decreasing ovulation, changing the mucus in the cervix to prevent passage of sperm, and altering the uterine lining.
Beyond contraception, levonorgestrel uses include treatment of heavy menstrual bleeding and dysmenorrhea, and endometrial protection during estrogen replacement therapy in postmenopausal women. LNG has been shown to be an effective treatment modality for a variety of gynecologic conditions including idiopathic, myoma- or adenomyosis-related heavy menstrual bleeding, endometriosis- or adenomyosis-related pelvic pain, endometrial hyperplasia, and early-stage endometrial cancer.
LNG is the levorotary isomer of norgestrel, a synthetic progestatonal hormone with actions similar to those of progesterone and about twice the potency of the racemic mixture. LNG binds to the progesterone receptor in the nucleus of target cells, resulting in a suppression of lutenizing hormone (LH) activity, an inhibition of ovulation, and alteration in the cervical mucus and endometrium.
The DetectX Levonorgestrel (LNG) Immunoassay kit is designed to quantitatively measure levonorgestrel present in serum, plasma, saliva, urine, dried fecal samples, water, and tissue culture media samples. In extracted serum, plasma and fecal samples, the kit measures total LNG (free and bound).