Routes of administration
Sven O. Skouby
Dept. OB/GYN, Frederiksberg Hospital, University of
Copenhagen, Denmark
Women who want safe, effective contraception have many more
options than they did only a few years ago. Each option must be weighed
carefully according to the needs and lifestyle of each particular woman.
Combined oral contraceptives (OCs) are still the preferred choice for the
majority of European women although the once daily administration result in
fluctuation of hormone plasma levels that may increase the incidence of side
effects.
The only contraceptive patch marketed, Evra®, delivers
norelgestromin and ethinyl estradiol (EE) transdermally. The patch is applied
once a week. Pharmacokinetic studies have shown that the concentrations of
norelgestromin and EE are within the ranges seen with OCs containing
norgestimate 250 µg and EE 35 µg, but without the peaks and the absorption
avoids the first-pass metabolism. The drug levels have been noted to remain
unaffected during conditions of heat, humidity, and exercise. The method failure
Pearl index is 0.7 and the incidence of adverse similar to that observed during
use of OCs. However, the patch seems to have a higher adherence rate for younger
users. A month’s supply is more expensive compared to OCs but may show cost
saving attributed to reduced costs of pregnancy.
The Nuva® vaginal ring is a soft, flexible, transparent polymer
and delivers etonogestrel and ethinyl estradiol The hormonal dose is comparable
to a pill containing 150 µg desogestrel and 30 µg EE. The advantage of the
ring is once-a-month insertion. However, if the ring is out of the vagina for
more than 3 hours, a back-up method is needed. When compared to OCs, the
incidence of irregular bleeding appears similar. Users of the ring group report
higher incidence of vaginal discomfort, but few feel the ring during intercourse.
The contraceptive patch and the vaginal ring offer additional
choice for women who wish to use a combined hormonal method of contraception