A balancing act
The drive to reduce estrogen-related side effects has led to a
progressive reduction in the estrogen dose of combined hormonal contraceptives.
However, lower estrogen-dosed combined oral contraceptives (COCs) have been
associated with unacceptable changes in bleeding pattern, the main factor
affecting user compliance and satisfaction. A recent Cochrane review found that
women taking lower estrogen-dosed COCs were more likely to discontinue studies
earlier and have more disruptions to bleeding patterns than women using COCs
with higher estrogen doses.
The pharmacokinetics of the vaginal route of hormonal delivery
has enabled NuvaRing® (15 µg ethinylestradiol (EE)/120 µg etonogestrel daily)
to defy this paradigm. The unique route of administration delivers consistent
and steady serum hormonal levels that contribute to NuvaRing’s excellent cycle
control profile. In a recent large-scale, randomized, comparative clinical trial
to compare NuvaRing’s cycle control and tolerability with a COC containing 30
µg EE/3 mg drospirenone (Yasmin), breakthrough bleeding or spotting during
cycles 2-13 was generally less frequent with NuvaRing (3.6-6.2%) than with the
COC (4.7-10.4%) and showed a statistically significant odds ratio of 0.61 (95%
CI: 0.46, 0.80) with longitudinal analysis. Intended bleeding (a representation
of an ideal bleeding pattern) was significantly better for all cycles with
NuvaRing than the COC (p<0.01). These results confirm the findings of a previous similarly designed trial in which NuvaRing was compared with a COC containing levonorgestrel (LNG) and 30 µg EE.
NuvaRing’s superior bleeding profile is particularly attractive
to women wishing to change from their current hormonal contraceptive. A recent
pooled data analysis showed that women are less likely to experience irregular
bleeding when switching to NuvaRing compared with COCs (30 µg EE/150 µg LNG
and 30 µg EE/3 mg drospirenone).
The other side of this balancing act-achieving a low incidence
of estrogen-related side effects-is accomplished through NuvaRing’s low estrogen
exposure. In the comparative trial between NuvaRing and Yasmin, women in the
NuvaRing group consistently reported a lower incidence of nausea, headache and
breast pain than those in the Yasmin group. Body weight, another factor
affecting compliance and tolerability, was also assessed in this study. Changes
from baseline in mean bodyweight and body composition parameters were relatively
small for both groups with no notable between-group differences.
It is well established that NuvaRing, with the convenience of
monthly dosing, is as effective as the Pill. Furthermore, its unique
pharmacokinetic properties enables NuvaRing to successfully achieve the
previously unattainable balancing act of excellent cycle control and low
estrogen-related side effects. Thus, the conventional paradigm of having to
choose between cycle control and estrogen-related side effects does not apply.