A multicenter study of levonorgestrel-estradiol contraceptive vaginal rings. I-Use effectiveness. An international comparative trial.

PIP: Contraceptive vaginal rings (CVRs), with approximate daily release rates of 250-290 mcg of levonorgestrel and 150-180 mcg of estradiol and manufactured in a shell design, were studied for effectiveness and acceptability in multicentered trials involving 1103 ring users in Brazil, Chile, Dominican Republic, Sweden, U.S., Denmark/Finland, and Nigeria. A comparison group of 533 women used the oral contraceptive Nordette. Both 1st and all segment 1 year gross pregnancy rates among CVR users were less than 3/100, rates similar to Nordette users. Continuation at 1 year was 50/100 users of the ring (all segments) and 38/100 among Nordette users, more of whom were lost to follow-up. Gross 1 year rates of termination for medical reasons ranged from 25-29/100. Ring users were more likely to terminate for vaginal problems and pill users for headache, nausea, and associated reasons. These trials indicate that CVRs of this design are as effective and have continuation rates equal to and possibly superior to Nordette under the same study conditions.^ieng

A multicenter study of levonorgestrel-estradiol contraceptive vaginal rings. II-Subjective and objective measures of effects. An international comparative trial.

Comparative clinical trials of 2 sizes of contraceptive vaginal rings and of an oral contraceptive were undertaken at 8 investigational sites (9 clinics). More than 500 women enrolled on each of the 3 study regimens. Side effects of the rings and of Nordette, the oral contraceptive, were evaluated by noting spontaneous complaints, by recording medications taken and by physical examination. Inquiries about changes in the frequency of specific conditions were made at the end of the subjects participation in the first year of the study. The incidence of spontaneous complaints was similar among users of the 2 different-sized rings and of the pill.

A multicenter study of levonorgestrel-estradiol contraceptive vaginal rings. III-Menstrual patterns. An international comparative trial.

Menstrual events among users of contraceptive vaginal rings (CVRs), releasing levonorgestrel and estradiol, were studied in comparison with a combined oral contraceptive, Nordette, in multicentered trials. CVRs were made with outside diameters of 50 and 58 mm and released about 250 micrograms and 290 microgram of levonorgestrel and 150 microgram and 180 microgram of estradiol per day, respectively. The CVRs were used continuously for 3 weeks and then removed for 1 week. Both the CVRs and Nordette were perceived to reduce menstrual flow and days of menstrual bleeding. Twenty to 25% of CVR users perceived increased intermenstrual bleeding or spotting. Diaries indicate, however, that on average, CVR users experienced about 1 day per month of bleeding or spotting with the ring in place. CVRs and Nordette produced approximately the same total number of bleeding and spotting days during 6 cycles of use, 27-29, but the small (50-mm OD) ring was associated with somewhat more spotting. This ring was also associated with somewhat more prolonged bleeding and spotting runs and with more prolonged nonbleeding intervals than reported by users of the larger (58-mm OD) ring or of Nordette. Differences among regimens, however, tended to be small even when statistically significant. Evidence from menstrual diaries indicates that these CVRs, and in particular 58-mm ring, provide control over the menstrual cycle comparable to the Nordette.

Paradoxical effect of flavoxate on human uterine contractility in vivo.

Flavoxate's effect on uterine contractility was investigated in 20 women with histories of primary dysmenorrhea. After 100 mg of the smooth muscle relaxant was infected intravenously, intrauterine pressure was recorded continuously for 1--2 hours. Immediately after the injection, intrauterine pressure and the frequency of contractions increased for 5--15 minutes at all phases of the menstrual cycle. After the activating response, there was a reduction in both the frequency of contractions and uterine tonus below preinjection levels in some patients. The paradoxical effect of flavoxate on uterine motility may be caused by its relaxation of vascular smooth muscle, which results in increased blood flow and, consequently, increased oxygen supply to the myometrium.

Spontaneous contractility and the response of the human uterine cervix to prostaglandins F2alpha and E2 during the menstrual cycle.

The effect of prostaglandins E2 and F2alpha on the contractility of the uterine cervix was investigated in nonpregnant women throughout the menstrual cycle. PGF2alpha was found stimulatory to the cervix at all phases of the menstrual cycle, whereas PGE2 was inhibitory. The relaxing effect of PGE2 was most marked during midcycle.