A balancing act

A balancing act

I. Milsom

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.

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