FERTILITY AND STERILITY Vol. 58, No.6, December 1992 Copyright CI 1992 The American Fertility Society Printed on ocid-free paper in U.S.A. A contraceptive subdermal implant releasing the progestin S1-1435: ovarian function, bleeding patterns, and side effects*t Marjut Laurikka-Routti, M.D.:j: Maija Haukkamaa, M.D., Ph.D. City Maternity Hospital, and Steroid Research Laboratory, Department of Medical Chemistry, University of Helsinki, Helsinki, Finland Objective: To study ovarian function, bleeding patterns, and side effects during the I-year use of a new modified contraceptive subdermal implant releasing the progestin ST-1435 with a lifetime of 2 years. Design, Patients: The effect on ovarian function and bleeding patterns of one contraceptive implant releasing the progestin ST-1435 was studied in 26 healthy women who volunteered. Side effects were recorded. Setting: The outpatient clinic of the City Maternity Hospital, Helsinki, Finland. Intervention: One ST-1435 contraceptive implant was inserted subcutaneously into the ventral aspect of left upper arm. Main Outcome Measures: The women attended the clinic at half-year intervals. Records of bleeding were kept. Blood samples were collected from 5 women before insertion of an implant, from 12 women during the first 5 to 6 weeks of use, and from 10 women during the 6th and 12th month of use. Serum concentrations of ST -1435, progesterone, and estradiol were determined. Side effects were reported. Results: The study covered 302 woman-months. The implant gave serum concentrations of ST- 1435 high enough to inhibit ovulation in all of the 37 analyzed cycles. No pregnancies occurred. Irregular bleeding or spotting was the main event observed, especially during the 1st year of use. One half of the users had irregular cycles. None of the women's implants was removed during 1 year of use because of irregular bleeding. The implant was well accepted and tolerated by the women; no hormonal side effects were reported. Conclusions: One single 4-cm subdermal ST-1435 implant with a lifetime of 2 years showed good contraceptive efficacy and led to suppression of ovulation. No hormonal side effects were reported. Irregular bleeding patterns were common but well-tolerated, and the implant had a high continuation rate. Fertil SterilI992;58:1l42-7 Key Words: Progestin, implant, ST-1435, ovarian function, bleeding, side effects, subdermal Received May 4, 1992; revised and accepted August 26, 1992. * This work was undertaken as part of the Contraceptive Development Program sponsored and coordinated by the International Committee for Contraception Research of the Population Council, Inc., New York, New York. t Financial support was provided by the George J. Hecht Fund, The Mellon Foundation, The Rockefeller Foundation, and the United States Agency for International Development through the Population Council, Inc., New York, New York as well as the Paulo Foundation, Helsinki, Finland. The content of this report does not necessarily reflect the policy of any of the funding sources. Steroid-releasing silastic implants inserted subdermally are known to give a constant slow steroid release and can be used for contraceptive purposes. Norplant (Leiras Oy, Turku, Finland) subdermal implants are widely used. This method that uses six implants has a long duration of effectiveness > 5 :j: Reprint requests: Marjut Laurikka-Routti, M.D., Steroid Research Laboratory, Department of Medical Chemistry, University of Helsinki, Siltavuorenpenger 10 A, SF -00170 Helsinki, Finland. 1142 Laurikka-Routti and Haukkamaa Contraceptive implant releasing ST-1435 Fertility and Sterility
years (1). Reducing the number of implants would make the insertion and the removal of the contraceptive implants easier; the ideal number would be one implant. Nortestosterone derivatives have steroidal side effects and, depending on the daily dose, could affect circulating lipoproteins (1-3). Therefore the steroid to be used in new implants should, if possible, have a structure that is not associated with these side effects. The progestin ST -1435, a 19-norprogesterone derivate, was synthesized by E. Merck, Darmstadt, Germany (4). This progestin was inactive by the oral route of administration (4) but potent when given in subcutaneous (SC) implants (4-8), intracervically (9), in transdermal gel (10, 11), or in vaginal rings (12). A single implant releasing ST-1435 has been effective in inhibition of ovulation (6, 8, 13) and to have a lifetime of 2 years (8). The progestin has not had androgenic side effects (4,6, 9, 14) and might be used as a contraceptive steroid during lactation (4, 15). The purpose ofthe study was to obtain more clinical experience with a new single subdermal implant releasing ST-1435 with a lifetime of 2 years. We report serum concentrations of ST-1435, ovarian function measured by serum concentrations of progesterone (P) and estradiol (E2), bleeding patterns, side effects, and acceptability during the 1 year of use of the ST-1435 implant. MATERIALS AND METHODS Study Subjects and Implants The study group consisted of 26 healthy volunteers who were between 20 and 36 years of age (28 ± 5 [mean ± SD]) in the beginning of the study. All had regular menstrual cycles before the insertion of the ST-1435 (16-methylene-17a-acetoxy-19-nor-4- pregnene-3,20-dione) implant, and none had used hormonal contraception for at least 1 month before implant insertion. The lifetime of one 4-cm implant containing 78 mg of ST-1435 was estimated to be 2 years, and only one implant was needed for contraceptive purpose (8). The sc implant was inserted into the ventral aspect of the left upper arm between the 1st and 7th day of the menstrual cycle under local anesthesia. The insertion technique was the same as with Norplant and published previously (1, 2). Gynecological examination was done before insertion and every 6 months until removal of the implant. Cervicovaginal smears were also taken from every subject at 1-year intervals. All subjects were asked to keep a record of bleeding. Every 6 months the subjects reported side effects and problems. After the 1st year of implant use, 16 study subjects answered a questionnaire concerning the acceptability and personal side effects of the contraceptive method. Blood Samples and Radioimmunoassay (RIA) Serum samples for the analysis of ST-1435, P, and E2 were obtained from 5 to 12 study subjects at different times. The samples were taken from the arm contralateral to the one in which the implant was inserted. Venous blood samples for the analysis of P and E2 were collected from 5 subjects during the luteal phase of the pretreatment cycle. The serum concentrations of ST-1435, P, and E2 were measured twice a week in 12 study subjects during the first 5 or 6 weeks of use. Six months later samples were collected from 10 subjects and 6 months later from 10 (after 12 months of use). Serum was separated by centrifugation, and samples were stored at -20 C until analyzed by RIA. The serum concentrations of ST-1435 were determined by RIA as described previously (16). The practical detection limit of the assay was 27.8 pmoljl. The intra-assay and interassay coefficients of variation (CVs) in the optimal range of study were 9.3% and 16.1 %. The serum concentrations of P and E2 were measured by RIA using the protocol from the World Health Organization (17). The practical detection limits of the assays were 0.64 nmoljl (P) and 73 pmoljl (E2). The intra-assay CVs in the optimal range of study were 4.0% (P) and 5.5% (E2) and interassays CVs 15% (P) and 11.7% (E2). Wilcoxon's signed rank test was used for statistical analysis. The P values were Bonferroni-corrected and P < 0.05 was considered statistically significant. The values are expressed as means ± SD. RESULTS Serum Concentrations of Progestin ST-1435 and Ovarian Function A total of 302 woman-months of use of the ST- 1435 implant were recorded. The mean (±SD) concentrations of ST-1435 at 6-month interval are shown in Table 1. The mean concentrations of ST- 1435 stayed above the minimal range (55 to 139 pmoljl), which is known to inhibit ovulation by ST- 1435 (13). Interindividual variations were seen in Vol. 58, No.6, December 1992 Laurikka-Routti and Haukkamaa Contraceptive implant releasing ST-1435 1143
Table 1 Serum Concentrations ofthe Progestin ST-1435, E 2, and P During the Use of Implant * Time ST-1435t P pmol/l nmol/l 1st month 167 ± 92 (122) 363 ± 177 (105) 1.2 ± 1.4 (126) 6th month 166 ± 61 (116) 303 ± 122 (114) 1.7 ± 0.7 (104) 12th month 138 ± 90 (110) 448 ± 405 (107) 1.4 ± 2.9 (99) * Values are means ± SD with number of samples in parentheses. t 100 pg/ml = 278 pmol/l. ~ 100 pg/ml = 367 pmol/l. 10 ng/ml = 32 nmol/l. ST-1435 concentrations. Estradiol levels fluctuated during the use of ST-1435 implants. Peak values were 1,035 pmoljl at 1 month, 756 pmoljl at 6 months, and 2,195 pmoljl at 12 months. The mean (±SD) concentrations of E2 (Table 1) did not vary during the time of the study. The five control cycles recorded were all ovulatory, and serum P ranged from 19 to 42 nmoljl. All of the analyzed cycles (37 measured treatment cycles) were anovulatory (Table 1). No persistent P elevation above 3.2 nmoljl was noticed, although fluctuation in E2, showing follicular development, was observed. No pregnancies were detected. Bleeding Control Twenty-three users ofthe ST-1435 implant kept bleeding records during the first 6 months of use and 21 during the next 6 months (6 to 12 months). A summary of the subjects' bleeding patterns during the 1 year of use of the ST-1435 implant is shown in Table 2. The cycles were judged as regular if the bleeding occurred every 21 to 35 days and as amenorrhic ifthere were more than 90 days of no bleeding or spotting. All other bleeding patterns were judged to be irregular (Table 2). Irregular bleeding was the most common abnormality reported. About half of the subjects had irregular bleeding or spotting. During the second 6 month-period, there were fewer mean spotting and bleeding days than during the first 6-month period. Episodes of amenorrhea were seen during the 1st year of the study in about one fourth of the subjects. Side Effects and Acceptability The most frequent side effects were bleeding disturbances during the 1st year of implant use. Only a few other side effects were noticed and then only transiently (Table 3). But when 16 study subjects were asked after use for 1 year, only 3 of 10 women with bleeding disturbances considered this as an unacceptable side effect. Eleven of 16 cited ease of Table 2 Bleeding Patterns During the Use of ST-1435 Implant Months No. of women Total bleeding days Total spotting days Bleeding and spotting days 1 2 23 23 3.7 ± 2.8 (4.0)* 3.3 ± 3.6 (3.0) 4.3 ± 4.0 (3.0) 5.0 ± 5.5 (3.0) 8.2 ± 5.3 (9.0) 8.3 ± 7.2 (10.0) Months 3 4 5 6 23 23 23 23 4.2 ± 4.1 (3.0) 4.0 ± 4.6 (3.0) 3.1 ± 4.8 (1.0) 2.8 ± 3.4 (2.0) 5.1 ± 3.8 (4.0) 3.1 ± 3.2 (3.0) 2.9 ± 3.4 (2.0) 4.0 ± 5.6 (2.0) 9.3 ± 6.5 (8.0) 7.2 ± 6.4 (5.0) 6.0 ± 7.0 (4.0) 6.8 ± 7.3 (4.0) Months o to 6 7 to 12 Oto 6 7 to 12 No. of women No. of bleeding episodes Total bleeding days Total spotting days Bleeding and spotting days 23 5.9 ± 3.2 (6.0) 21 ± 15 (16) 24 ± 18 (21) 45 ± 28 (40) 21 5.2 ± 2.9 (6.0) 17 ± 16 (13) 16 ± 15 (10)t 34 ± 26 (28)~ Longest nonbleeding interval (d) Longest bleeding and spotting run (d) Regular cycles Irregular cycles Amenorrhea 23 54 ± 39 (44) 13.0 ± 7.1 (12.0) 8 11 4 21 76 ± 50 (67) 8.0 ± 6.5 (6.0) 5 11 5 * Values are means ± SD with median in parentheses. t Total spotting days decreased significantly during the second half year (P < 0.05). ~ Bleeding and spotting days decreased significantly during the second half year (P < 0.05). 1144 Laurikka-Routti and Haukkamaa Contraceptive implant releasing ST-1435 Fertility and Sterility
Table 3 Side Effects During the Use of ST-1435 Implant 6mo Duration of use 12 mo No. of subjects 24 23 No. of subjects discontinued 1 2 No side effects 12 12 Bleeding disturbances 10 8 Irregular bleeding 7 7 Oligoamenorrhea 3 1 Depression 2* Mastalgia, transient It It Headache 1* 1* Weight gain 1 * Subjects had this feeling, but they had had it before too. t Different subjects. use as an advantage of this contraceptive method. Two had easier menstruation than before, less dysmenorrhea, and the quantity of bleeding was smaller. Four of 16 subjects noticed no advantages or disadvantages of this contraceptive method. After the 1st year of use of the ST-1435 implant, 6 of 16 users were very satisfied, 7 satisfied, 2 dissatisfied, and 1 could not tell. If this method of contraception were a commercial product, 13 of 16 study subjects would continue the use of the method after the study with a new implant and recommend it to their friends. No infections occurred after insertion (n = 26) or removal (n = 3) of the implants. Gynecological examinations did not reveal any abnormalities. One cervicovaginal smear was class II, but after 6 months it was normal class I. One cervicitis caused by Chlamydia trachomatis was treated during the study. Two of the study subjects requested to have the implant removed so that they could plan a pregnancy (1 after 6 months and the other after 1 year). One other subject asked to have the implant removed after 8 months, citing personal problems. In this case, she clearly had had bleeding disturbances, i.e., irregular cycles, although she had not kept a bleeding record. After 1 year of use, the implant was not removed because of bleeding problems from any of the 26 subjects. The continuation after 1 year of use of the implant was 23 of 26 (89%). DISCUSSION The aim of this study was the development of a single implant method: a second generation implant. The first clinical trials with ST-1435 subdermal implants were done in 1976 (5): 3 or 5 SC implants containing 35 mg of ST -1435 each were inserted into 285 women. The lifetime of these implants was 300 days on an average. Only two pregnancies occurred after 11 and 19 months of use, showing the progestin to be highly effective. After these promising results, ST-1435 implants in different lengths have been studied (4, 6, 7, 13, 16). Subcutaneous implants releasing ST-1435 have been shown to effectively inhibit follicle development and ovulation with serum concentrations of ST-1435 in the range of 150 to 300 pg/ml with three implants containing 40 mg ST-1435 each (16) and 50 to 220 pg/ml with one implant (13). When serum ST-1435 concentrations decreased to 50 to 100 pg/ml (139 to 278 pmoljl), the first E2 increase was seen showing the start of follicle development, but P remained low showing inhibition of ovulation (13). Serum levels of ST-1435 constantly above 56 pmoljl were observed to prevent ovulation (13). The serum concentrations of the steroid in the range of 138 to 167 pmoljl (mean) achieved in our study allow follicle function but inhibit ovulation. Ovulation inhibition by ST -1435 is achieved via different mechanisms depending on the serum progestin concentrations: high levels inhibit ovulation via both central and direct ovarial mechanism, whereas low doses inhibit only via the central mechanism (the positive feedback of E2 on midcycle gonadotropin surge is abolished, and decreased luteinizing hormone/follicle-stimulating hormone ratio is achieved) (18). Interindividual variations in serum ST-1435 levels were observed in this study as well as in the previous studies using ST-1435-releasing implants and implants releasing megestrol acetate, d-norgestrel, and norethindrone (19-21). It might be partly explained by differences in sex hormone-binding globulin (SHBG) binding capacity between individuals (19) in the case of levonorgestrel and norethindrone, progestins with high affinity to SHBG. But in the case of ST -1435, which is not bound by SHBG or corticosteroid-binding globulin (22), the interindividual differences could be because of differences in hepatic metabolic capacities (23). In previous studies, the exhaustion of implants has been rapid up to 1 year, demanding frequent reinsertion, and the steroid doses have been too high during the first months of use causing hypoestrogenism (4, 6, 7, 13, 16). Now we seem to have an implant with a rather sustained release of steroid at levels that inhibit ovulation but allow follicular de- Vol. 58, No.6, December 1992 Laurikka-Routti and Haukkamaa Contraceptive implant releasing ST-1435 1145
velopment and thus do not cause changes in E2 levels, and a single implant method with a lifetime longer than before: 2 years (8). Norethindrone acetate has been tested as a single contraceptive implant, but the pregnancy rate with this progestin was high (24). A single se implant releasing 3-keto desogestrel has been tested in a small trial (8 subjects) (25). All subjects had bleeding abnormalities, and only two subjects continued to the end of the study (1 year). During the use of ST-1435 implants in previous studies, amenorrhea was very common (83% without bleeding over 60 days) (4). But now with a more optimal dose ofthe progestin than before, one fourth of subjects at most had amenorrhea, and at least half of the subjects had regular periods. Very few side effects except bleeding abnormalities have been reported during the use of high doses (120 tt/d) of ST-1435 (6). Eight of 282 subjects had nervousness, 7 headache, 4 decreased libido, but hoarseness and acne occurred in only 1 subject each (6). In our study, no androgenic hormonal side effects were reported, and the few side effects that occurred were transient. According to previous studies, the progestin ST-1435 has not caused the changes in lipid values, typical for androgenic progestins (7, 14). The new contraceptive implant was accepted well. The most frequently observed side effect was excessive bleeding and spotting, which did not cause any removals of implants after 1 year. The continuation rate for the implant was almost 90% after the 1st year. During the use of the implant releasing the high dose of 120 ttg/d of ST-1435 with the lifetime of 6 months and a high continuation rate of 81.4%, 11 of 282 subjects requested discontinuation because of excessive bleeding (6). Twenty-six percent of Norplant implants were removed because of bleeding disturbances after 1 year (3). In conclusion, a single 4-cm subdermal implant releasing the progestin ST-1435 in low doses seems to be an effective contraceptive method. During the use of the implant, concentrations of serum Pare low showing anovulation, but excessive suppression of ovarian function is not seen. Hormonal side effects were not reported. Irregular bleeding patterns are common but well accepted, and the implant has a high continuation rate. REFERENCES 1. Shoupe D, Mishell DR Jr. Norplant: subdermal implant system for long-term contraception. Am J Obstet Gynecol 1989;160:1286-92. 2. Tikkanen MJ, Nikkilii EA. Oral contraceptives and lipoprotein metabolism. J Reprod Med 1986;31:898-905. 3. Olsson S-E, Odlind V, Johansson EDB, Sivin I. Contraception with NorplantR implants and Norplant R -2-implants (two covered rods): results from a comparative clinical study in Sweden. Contraception 1988;37:61-73. 4. Odlind V, Lithell H, Kurunmiiki H, Liihteenmiiki PLA, Toivonen J, Luukkainen T, et al. 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