Levonorgestrel, Pharmacokinetics, Efficacy and Safety 49respond fairly well to oral medroxyprogesterone acetate or micronized
progesterone, but treatment with oral progesterone sometimes is associated
with intolerable side effects and patients may not be able to continue oral
progesterone treatment. During the last 10 years, LNG-IUD has been
introduced in the treatment of endometrial hyperplasia. Several studies have
shown a complete response (reversal of endometrial hyperplasia to a
progestational-type endometrium) in 25 to 90% of cases. In general,
endometrial hyperplasia responds better (90–100% response) than endometrial
intraepithelial neoplasia (67–88% response) to intrauterine LNG [74- 7 6]. In
addition to the dominant progestational effect of Mirena on the endometrium,
adverse events (side effects) that are commonly experienced by patients on
oral progestational therapy are considerably reduced. This is because the
systemic absorption of LNG is considerably reduced compared to oral
progestational therapy [74-77].
In a small study of 20 women, which included 12 women with
endometrial hyperplasia without atypia and eight women with atypia, LNG-
IUD was found to be very effective over a period of 36 months. At the start of
the study, all women with atypical hyperplasia showed progesterone receptor
expression in the epithelial cells. There was a significant decline in
progesterone receptor expression over the course of the study, suggesting the
strong antiproliferative effect of the LNG-IUD [78].
In a prospective randomized study, Dolapcioglu et al. compared the
efficacy of LNG-IUD to oral progestin for the treatment of endometrial
hyperplasia. A higher success rate was noted with LNG-IUD compared to oral
MPA. The success rates of LNG-IUD treatment and oral medroxyprogesterone
for three months therapy were 84% and 50%, respectively. In the six-month
treatment group the regression rate was even higher, 100% with LNG-IUD and
64% with oral medroxyprogesterone. LNG-IUD was found to have a
significantly higher success rate [79].
Another study compared the efficacy and safety of the LNG-IUD with
dydrogesterone in 138 patients with endometrial hyperplasia without atypia.
LNG-releasing IUD has been shown to be highly effective in the treatment of
endometrial hyperplasia. After 6 months of treatment, endometrial hyperplasia
regressed in 96% of women in the LNG-IUD group versus 80% of women in
the oral group. Minimal differences were noted regarding adverse effects
between the two groups. Intermenstrual vaginal spotting and amenorrhea were
more common in the LNG-IUD group. Patient satisfaction was significantly
higher in the LNG-IUD group. Hysterectomy rates were lower in the LNG-
IUD group than in the oral treatment group Recurrence rate was 0% in the