Release rates of levonorgestrel from Silastic capsules, homogeneous rods and covered rods in humans

Development of an aciclovir implant for the effective long-term control of herpes simplex virus type-1 infection in Vero cells and in experimentally infected SKH-1 mice

Human herpes simplex virus type-1 (HSV-1) is treatable with oral doses of an antiviral agent such as aciclovir (ACV), a drug that has poor bioavailability. An alternative for delivering ACV would employ a long-lived subcutaneous implant that would allow for near zero-order drug delivery kinetics. This study aimed to develop an implant composed of a matrix of silicone and ACV that is capable of sustained long-term release of ACV. Once the implants had been created, release of ACV from the implants was determined and quantified in vitro using a spectrophotometric assay for the drug. Solvent-exposed surface area of the implant (2.86 mm(2), 6.28 mm(2), 34.62 mm(2) and 100.48 mm(2)) had a significant effect on release kinetics, whereas temperature (37 degrees C, 25 degrees C and 4 degrees C) and pH (6.0, 7.0 and 8.0) did not. The implants were also used successfully to suppress HSV-1 (KOS)-induced cytopathic effect in cultured Vero cells. The implants protected HSV-1-infected SKH-1 mice from viral reactivation (n = 37; P = 0.0367) via ultraviolet light compared with mice that were untreated (n = 37). Furthermore, mice that received silicone-only implants had no lowered risk of reactivation (n = 34; P = 0.7268), demonstrating the antiviral efficacy of the ACV implants.

Transition from Norplant to Jadelle in a clinic with extensive experience providing contraceptive implants

OBJECTIVE

The purpose of this study was to understand the transition process from providing Norplant, the six-capsule first contraceptive implant system, to providing Jadelle, the two-rod second-generation system, in a clinical setting with extensive experience providing Norplant implants.

MATERIALS AND METHODS

Two hundred forty-nine women requesting contraceptive implants from the PROFAMILIA clinic (Santo Domingo, Dominican Republic) were provided with information regarding the differences and similarities between the two implant systems being studied, including the easier insertion and removal procedures and the possible shorter use life associated with Jadelle. A questionnaire evaluating their preference and the reason why they chose either system was provided. The health care providers' opinions about the two systems were also studied.

RESULTS

Fifty-three percent of the women preferred Jadelle over Norplant. The main reason behind their preference for Jadelle was its reduced number of implants with easier insertion and removal and less visibility in the arm, whereas that for Norplant was greater familiarity. Providers overwhelmingly preferred Jadelle. A 1-h presentation was sufficient training for providers experienced with Norplant. None had any problem with the management of Jadelle.

CONCLUSION

The inclusion of Jadelle in a clinic with extensive experience with Norplant was easy and uneventful, but both methods should be available during a transition period of several months while confidence in the new method is being acquired by the community.

A cross-sectional study of the forearm bone density of long-term users of levonorgestrel-releasing intrauterine system

BACKGROUND

There are concerns about the effect of hormonal contraceptives on bone mineral density (BMD), but there is currently no information available on the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS) on BMD. The objective of this study was to compare the BMD of LNG-IUS users with that of controls using the TCu380A intrauterine device (IUD).

MATERIALS AND METHODS

A cross-sectional study paired 53 women, aged 25-51 years, who had been using the LNG-IUS for 7 years, with 53 IUD users, according to age (+/-1 year) and body mass index (BMI; kg/m2) (+/-1). BMD was evaluated at the midshaft of the ulna and the distal radius of the nondominant forearm using double X-ray absorptiometry.

RESULTS

Mean age of women was 34 years. BMI was slightly over 25 in both groups. Estradiol was normal. Mean BMD was 0.469 +/- 0.008 and 0.467 +/- 0.009 and 0.409 +/- 0.009 and 0.411 +/- 0.009 at the midshaft of the ulna and distal radius in LNG-IUS and IUD users, respectively, without significant differences.

CONCLUSIONS

Women aged 25-51 years, using the LNG-IUS for 7 years, had a mean BMD similar to that of the control group of TCu380A IUD users.

Study on accelerated evaluation system for release profiles of covered-rod type silicone formulation using indomethacin as a model drug

The purpose of this study was to establish a method allowing rapid evaluation in vitro of the profiles of drug release from covered-rod type silicone formulation (CR silicone formulation), which releases drug for a prolonged period of time. Three CR silicone formulations containing indomethacin (IDM) with different release profiles were used in this study. The release of IDM was accelerated in a mixture of methanol and water (MeOH/water) compared with in phosphate-buffered saline (PBS) added by Tween 20 (PBS-based solvent). The velocity of IDM release varied depending on the composition of the MeOH/water. The change in release velocity was dependent on the solubility of IDM and the permeability of IDM through the silicone membrane. In all the tested formulations, the release rates of IDM estimated in 90% (v/v) MeOH/water were equally 14.6 times faster than those estimated in PBS-based solvent. Release of IDM from the cross-sections and lateral side evaluated by a bi-directional elution cell were accelerated in the MeOH/water in a similar degree. By introducing a common factor to shorten the time axis in all formulations, a fairly good agreement was observed between the two release profiles obtained in the accelerated MeOH/water system and the usual PBS-based solvent system. These results indicate that MeOH/water system enables to reduce the period for evaluation of profiles of drug release from CR silicone formulations in reflecting their release characteristics in usual PBS-based solvent system.

Design of controlled-release formulation for ivermectin using silicone

The purpose of this study was to design a formulation using silicone as carrier, so that release of ivermectin (IVM) can be controlled for a long period of time. The lateral side of a cylindrical matrix-type formulation composed of IVM and silicone was covered with silicone to obtain a covered-rod (CR) formulation. With this formulation, linear release of IVM was obtained. With addition of polyethylene glycol 4000 (PEG), release of IVM was accelerated. In a trial with subcutaneous administration to mice, blood concentration of IVM was maintained within one-order over a period of 3 months. The velocity of release of IVM from CR preparation depended on the change in solubility of IVM by additives, and in the case of a formulation with addition of desoxycholate sodium, linear in vitro release of IVM was observed over a period of 1 year.

Investigation of the release behavior of a covered-rod-type formulation using silicone

The purpose of this study was to investigate the effects of the properties of a drug on its release behavior in a cylindrical sustained-release formulation having a two-component structure, with a silicone matrix containing drug powder as the inner layer component, and with its lateral side covered with an silicone outer layer (CR silicone formulation). In this study, the release profile of a drug from "the lateral side covered with silicone" and from "the cross-sections where the inner layer is exposed to the surface" was examined using a newly designed bi-directional elution cell. The relationships between the release profile and solubility of the drug and its permeability through silicone were also studied. Bovine serum albumin (BSA), antipyrine (ANP), indometacin (IDM) and ketoprofen (KP) were used as model drugs. Each CR silicone formulation containing drug powder consisting of a drug and sucrose (SUC) was investigated, and a satisfactory relationship was observed between drug release from the cross-sections and drug solubility, and between drug release from the lateral side and permeability of the drug through a silicone membrane. For CR silicone formulations containing IDM, the addition of deoxycholate sodium (DOC) improved the solubility of IDM; however, release from the lateral side of the formulation remained unchanged, and IDM release from the cross-sections of the formulation increased. In this study it was found that, for controlled release of a drug from CR silicone formulations, control of drug solubility is effective.

New drug delivery system for water-soluble drugs using silicone and its usefulness for local treatment: application of GCV-silicone to GCV/HSV-tk gene therapy for brain tumor

Controlled release of a water-soluble low-molecular-weight drug from silicone and its usefulness as a local therapeutic drug were studied. For application to ganciclovir/helpes simplex virus thymidine kinase (GCV/HSV-tk) suicide gene therapy for brain tumor, two kinds of GCV-containing silicone formulations were prepared for evaluation. In vitro, GCV release from matrix-type formulation consisting of a single matrix was characterized by Fickian diffusion, while covered-rod-type formulation, in which the side surface of the outer layer was covered with 100% silicone, exhibited a near-zero-order release pattern. In an in vivo study using a rat 9L glioblastoma model, administration of GCV-silicone formulation into brain tumor yielded sustained intracerebral GCV concentration for 4 days after administration, with excellent antitumor effect equal to or better than that of daily intraperitoneal administration of aqueous solution of GCV, at a dose less than 1/100 of the total dose of solution for intraperitoneal administration. Furthermore, GCV was undetectable in blood, suggesting that decrease in systemic adverse reactions can be expected with intracerebral administration of GCV-silicone formulation.

Progestin implants for female contraception

Four different implants, in the form of capsules or covered rods, that release one of the synthetic progestins levonorgestrel, etonogestrel, Nestorone, or Elcometrine and nomegestrol acetate were reviewed. Biocompatible polymers or copolymers of polydimethyl/polymethylvinyl-siloxanes or ethylvinylacetate are used to hold the steroid crystals and to control the rate of release. Once inserted under the skin, these implants release the corresponding steroid continuously over prolonged periods, a process that can be readily interrupted by implant removal. During long-term use of the implant, the released steroid circulates in blood at a fairly stable level. The physical characteristics of the implants, including drug contents and rate of release, serum levels of the progestin during use, and the duration of their effective life are described. Total steroid loads vary in the range of 50 mg to 216 mg; average release rates are in the range of 30-100 ug/day, and effective lives from 6 months to 7 years.

A 4-year follow-up study of women with Norplant-2 contraceptive implants

One-hundred-thirty of 178 women who received Norplant-2 implants were followed prospectively for 4 years. Menstrual disorders were the most common reason for discontinuation. Only one patient conceived, for a failure rate of 0.6%.

Development of new drug delivery system for protein drugs using silicone (I)

A novel technique, by which protein drugs effective in small doses can be released over a long period, was developed using silicone and a water-soluble substance. In this study, interferon (IFN) was used as a model of the protein drugs. The IFN-silicone formulation released IFN over long periods of time in vitro and suppressed tumor growth in nude mice for about 100 days after a single administration. This indicates that physiologically active IFN is released over a prolonged period of time from the IFN-silicone formulation in vivo. Silicone formulations are expected to be a practically feasible sustained-release formulation.

The use of long-acting contraceptives in adolescents

DMPA and implants have played an important role in the attempt to prevent teenage pregnancies. Adolescent health care providers should provide continued counseling to girls using DMPA or implants and should promptly address any concern associated with these methods. Future studies are warranted to explore ways to prevent or reduce the side effects of DMPA and implants, as well as to develop new, optimal, long-acting contraceptives. Detailed baseline information should be obtained in every future study that explores the presence of side effects during the use of long-acting contraceptives.

The pediatrician and the sexually active adolescent. Sexual activity and contraception

Sexuality and its resultant consequences continue to be major issues for adolescents and for those who provide their health care. This article discusses current sexual behavior in adolescents and describes the various forms of hormonal contraception that sexually active adolescents should use.

Clinical performance of a new two-rod levonorgestrel contraceptive implant: a three-year randomized study with Norplant implants as controls

In a randomized three-year clinical trial at seven clinics, the performance of levonorgestrel rod (LNG ROD) implants used by 600 women was compared with that of soft tubing NORPLANT implants used by 598 women. No pregnancies occurred in either group of women and, accordingly, body weight did not affect the efficacy of either type of implant. There were neither statistically significant nor important differences in termination rates for any reason over the three years. Complaint and illness rates during use of either of the two implant types were statistically indistinguishable and were attributable to the same set of conditions. Seventy-one per 100 of the women using each implant regimen continued to the three-year point, for an average annual continuation rate of 89 per 100. Removals of LNG ROD implants were accomplished in about half the time required for removal of Norplant capsule implants (p < 0.001).

Menstrual bleeding patterns in Norplant-2 implant users

The objective of the present study was to analyze the patterns of menstrual bleeding in Singaporean women using Norplant-2 contraceptive implants over a five-year period. Of the 100 women recruited for the study, 62 were still using the implant at the end of five years. Only 9 women discontinued for menstrual reasons and they did so within the first 21 months of implant use. Although a normal menstrual bleeding pattern was uncommon during the first three months of use, 69.4% had normal menstruation at the end of five years. Irregular bleeding was the most common form of menstrual abnormality throughout the study period. Infrequent periods and amenorrhoea were distinctly uncommon, especially after the first two years of use. The pattern of bleeding with Norplant-2 was not significantly different from that previously observed with Norplant.

Androgen levels in women using a single implant of nomegestrol acetate

This study was undertaken to evaluate the effects of a single implant containing nomegestrol acetate (Uniplant) on plasma levels of sex hormone-binding globulin (SHBG), testosterone, free testosterone, androstenedione and on blood pressure, body weight, and the development of acne vulgaris. Plasma levels of sex hormone-binding globulin, testosterone, free testosterone and androstenedione were measured. Blood pressure and body weight were determined. The development of acne vulgaris was evaluated. Total testosterone and androstenedione decreased significantly during two years of Uniplant use but all levels were within the normal range. There were no significant differences in sex hormone-binding globulin and free testosterone during 24 months of Uniplant use. All changes observed in this study were within normal range. SHBG was not affected by Uniplant use. No significant increase in androgen levels and in the development of acne vulgaris was observed in these women using nomegestrol acetate implant during two years. Based on these results, it is possible to conclude that Uniplant had no androgenic effect in women during this study.

Contraception. A clinical review for the internist

Effective use of contraception allows couples to control their fertility and, in certain instances, is associated with important noncontraceptive benefits. Surgical sterilization offers safe, effective, and permanent contraception for women and men. Low-dose OCPs offer safe, effective contraception for most women able and willing to take pills consistently. In addition, their use confers a variety of important noncontraceptive benefits. The availability of long-acting progestin injectable and implantable methods has made highly effective and convenient birth control available for women who are not good pill takers as well as for those for whom contraceptive doses of estrogen are contraindicated. Barrier methods are readily available and provide protection against STDs; unfortunately, erratic use is all too often associated with inadequate contraceptive efficacy. IUDs offer convenient, highly effective contraception for appropriate candidates.

A five-year evaluation of NORPLANT II implants in China

A five-year study of NORPLANT II rod implants was undertaken in four large cities and metropolitan areas in eastern China. Designed to test the safety, efficacy and acceptability of these implants, the study involved 1,208 women and was conducted concurrently with a similar study of NORPLANT capsule implants. At the end of five years, the gross pregnancy rate was 0.65 per 100, and the continuation rate was 65.3 per 100. Both these values were similar to and not statistically different from the rates of the capsule implant users. In 4,828 woman-years of use, there were few severe adverse events reported. Users and providers found the method to be an acceptable long-term contraceptive method of great reliability.

Cytokeratins 8, 18 and 19 in endometrial epithelial cells during the normal menstrual cycle and in women receiving Norplant

Cytokeratins 8, 18 and 19 are members of the cytoskeletal intermediate filament protein family. They are expressed in all simple epithelial tissues, including endometrium, and are recognised as dynamic structures that can be affected by numerous external factors. The Norplant system is a subdermal slow release levonorgestrel implant commonly used as a long-acting progestogen contraceptive. Norplant implants have been shown to have atrophic effects on endometrial epithelial and stromal cells, and cause a range of endometrial bleeding problems among users. The aim of this study is to describe changes in the immunohistochemical expression and distribution of cytokeratins 8, 18 and 19 in endometrial epithelial cells of Norplant implants users and normal menstrual cycle controls. Endometrial biopsies were collected from 65 control normal cycle women and 37 Norplant implants acceptors. The normal menstrual cycle was classified histologically into 9 stages; one menstrual, five proliferative and three secretory. Norplant implants bleeding patterns were categorised into 6 groups according to current World Health Organisation (WHO) definitions; amenorrhoea, frequent bleeding, infrequent bleeding, irregular bleeding, "normal" bleeding, and prolonged bleeding. The tissues were fixed in formalin, embedded in paraffin, and stained immunohistochemically. Semi-quantitative scoring of the staining intensity was performed. Apical versus basal intracellular cytokeratin distribution was also evaluated. The staining intensity was significantly stronger in control endometrial tissue compared to Norplant implants tissue. In control tissues, cytokeratins were predominantly located in the apical region of epithelial cells (52% of biopsies) and in Norplant implants tissues they were predominantly distributed equally between the apical and basal portions of epithelial cells (43% of biopsies). There was no particular cytokeratin distribution pattern associated with the different stages of normal cycle or the different Norplant implants bleeding patterns. It was concluded that long-term exposure to levonorgestrel significantly reduced the cytokeratin expression in endometrial epithelial cells (P < 0.001).

Advances in Hormonal Contraception

Breakthroughs involving innovative methods of hormonal and nonhormonal birth control have been severely limited in the United States over the last 30 years. This trend has changed with the introduction of new choices in birth control in the 1990s. This article focuses on these advances in hormonal contraception and provides information on the use of oral contraceptives, hormonal implants, and injectable methods of contraception currently available in the United States. Each method is assessed and recommendations are made for proper patient and method selection. This information is intended to supply the pharmacist with sufficient information to appropriately counsel patients on the use of hormonal contraception in the 1990s.

Free levonorgestrel index and its relationship with luteal activity during long-term use of Norplant implants

Levonorgestrel serum levels and sex hormone binding globulin (SHBG) were measured in 82 women during different years of use of Norplant implants. The ratio between levonorgestrel and SHBG was calculated as an indicator of the free biologically active fraction of levonorgestrel (free levonorgestrel index, FLI). These parameters were then correlated with the presence of luteal activity, as determined by progesterone levels above 9.6 nmol/L, in a sampling run of 10 samples taken twice a week for five consecutive weeks. Levonorgestrel serum levels remained constant around 1.0 nmol/L during the five-year period. SHBG levels were below normal for the first 18 months of use, returning to normal levels during the last three years of use. The FLI in the first two years was significantly higher than that observed in the later years. The frequency of cycles with luteal activity was 12% during the first 2 years, increasing to 44% in the latter years, when FLI levels were lower. Our results suggest that the changes in SHBG and consequently in the free biologically active fraction of levonorgestrel may largely account for the differences in degree of ovarian suppression observed between the first two years of use of Norplant implants and the latter three, even in the absence of a significant variation in total levonorgestrel concentrations.

Clinical results with subcutaneous implants containing 3-keto desogestrel

Eight healthy women using one Silastic implant of 30 mm length filled with 3-keto desogestrel, the active metabolite of desogestrel, were studied for 36-664 days. The release rate of 3-keto desogestrel was quite constant and around 30 micrograms/day. No ovulations occurred. One woman was amenorrheic, while the others had different bleeding patterns, often with periods of spotting. No other side effects were recorded. The mean plasma levels of 3-keto desogestrel were 0.9 nmol/l after 1 month and 0.5 nmol/l after 12 months. 3-Keto desogestrel was less effective than testosterone, estradiol or levonorgestrel in displacing 3H-dihydrotestosterone from SHBG. It is concluded that contraception with 3-keto desogestrel delivered through an implant is a promising method for further investigation. With a single implant we found a duration of at least one year.

In vitro characterization of secretion rates from silastic micropellets containing estradiol

For local, controlled steroid hormone administration into tissues, such as the brain, we have prepared cylindric micropellets of 1 mm in length and 1 mm diameter. The micropellets are a mixture of silicone glue (silastic) and 0.1%, 1.0%, or 10% estradiol (E2). To evaluate in vivo E2 secretion rates, micropellets were implanted into the brains of 40 rats for either 1, 4, 8, or 12 weeks. In vitro 24 h E2 secretion rates of these implants were compared-after removal from the rat brain-with 24 h secretion rates of micropellets that had been incubated for the same periods of time in vitro only. In vitro release of E2 decreased steadily but asymptotically from the first day of incubation to the 3rd or 4th week, when an apparent steady state is achieved. With any E2 concentration the coefficient of variation for 24 h release rates rarely exceeded 15% within a group. The release rates increased nonlinearly with the concentration of E2 in the pellet. Subsequent to in vivo implantation the in vitro secretion of E2 was slightly higher than the in vitro secretion of micropellets incubated for the same period of time in vitro. Thus (1) the secretion rate from a pellet can be predicted rather exactly by the mixing ratio of silastic and E2 and (2) the secretion rate from the micropellet in vitro and in vivo appears to be rather similar. It is concluded that the method described is very useful for short-term (days) or long-term (weeks, albeit not constant) local exposure of defined tissues to steroid hormones.

Norplant: subdermal implant system for long-term contraception

Norplant offers long-term contraception through the use of subdermal capsules filled with levonorgestrel. The six capsules are implanted in the inside part of the upper arm. The levonorgestrel is released from the capsules gradually, providing contraception for about 5 years. The primary mechanism of action of Norplant is suppression of ovulation. Studies have shown a pregnancy rate of 0.6/100 woman-years after 1 year and a cumulative rate of 1.5/100 woman-years at 5 years. Principal side effects are irregular menstrual bleeding and headaches. No changes in carbohydrate metabolism, blood coagulation, or liver function have been reported. Lipid levels have decreased 5% to 15%. After removal of Norplant, fertility returns rapidly, and there have been no adverse effects on infants. Norplant is currently approved in 12 countries; clinical trials are being conducted in 37 countries.

Reduced incidence of rabbit endometrial neoplasia with levonorgestrel implant

To test the hypothesis that progestogens protect against the development of endometrial neoplasia, we placed polydimethylsiloxane implants (levonorgestrel or inert) into the right uterine horn at random in 114 old female rabbits. Cross-sectional uterine biopsy specimens were taken from both horns at the time of implantation and at 6, 12, and 24 months thereafter. Twenty-nine levonorgestrel-treated and 33 controls survived to the completion of the study. The incidence of endometrial neoplasia of 17.2% in the group treated with levonorgestrel was significantly less (p less than 0.05) than the 42.4% incidence observed in the control does. Before the completion of the study, one levonorgestrel-treated doe died and was found to have an endometrial tumor. When the findings of this doe are included in the report, the statistical significance is marginally lost. No endometrial neoplasia was found in the eight does with serum levonorgestrel concentrations greater than 0.12 ng/ml. Only one of the five tumors in the levonorgestrel-treated group occurred in the horn containing the levonorgestrel implant, which suggests that a dose effect is likely. Treatment with levonorgestrel decreases the incidence of endometrial neoplasia in rabbits. This finding gives further credence to the use of progestogen supplementation in women at risk for developing endometrial neoplasia.

Contraception with NORPLANT implants and NORPLANT-2 implants (two covered rods). Results from a comparative clinical study in Sweden

Two-hundred-and-forty healthy women, ages 18 to 40 years, were randomized in a ratio of 2:5 to use NORPLANT implants or NORPLANT-2 implants. Through three years of use, no pregnancies were recorded among women using NORPLANT implants and two pregnancies were noted among women using NORPLANT-2 implants resulting in a cumulative net pregnancy rate of 1.3 +/- 0.9 per 100 acceptors (mean +/- SE) by the end of year three. This difference was not statistically significant. During the fourth year, no pregnancies were observed in the NORPLANT group, but 4 pregnancies occurred in the NORPLANT-2 group. The most common reason for terminating the study was bleeding disturbances. During the first year there were significantly more terminations due to bleeding problems in the NORPLANT group than in the NORPLANT-2 group. However, during the second year of use the proportion of women discontinuing for bleeding problems dropped considerably among NORPLANT users and during the third year very few women in either group discontinued because of bleeding problems. The continuation rates after one year were for NORPLANT users 59.4% and for NORPLANT-2 users 77.2%. Corresponding figures after three years of use were 46.1% and 51.7%, respectively. The second most common reason for discontinuation was depression and other mood changes. In both groups we noted a slight increase in weight during the study and a slight decrease in blood pressure and hemoglobin levels with time. In conclusion, both NORPLANT and NORPLANT-2 implants are very effective methods for contraception. The efficacy of NORPLANT-2 implants, however, was not acceptable during the fourth year of use in this study. The latter system could, however, become a suitable three-year contraceptive method, possibly with less bleeding disturbances than NORPLANT in the first year.

Plasma levels of cortisol and corticosteroid binding globulin during use of Norplant-2 implants

Plasma levels of cortisol and corticosteroid binding globulin (CBG) were studied during one year in eleven healthy women using NORPLANT-2 implants. NORPLANT-2 implants release approximately 50 ug of levonorgestrel/day. A significant diurnal variation of cortisol levels was found during the study. No significant change in cortisol levels compared to pretreatment levels was found. Levels of CBG showed no diurnal variation, but decreased significantly during use of the implants. This was most probably due to a direct effect of the levonorgestrel, as the levels of estradiol did not change compared to pretreatment levels, except for the values after 6 months that were significantly lower than pretreatment levels. A "free cortisol index" calculated as: level of cortisol/level of CBG, was unchanged during treatment compared to pretreatment levels. It is concluded that although CBG levels were reduced, no significant change in cortisol patterns was seen during use of the implants.

Reversal of testicular function after prolonged suppression with an LHRH agonist in rhesus monkeys

Using subcutaneously implanted osmotic pumps, four male rhesus monkeys were continuously infused for 18 months with 100 micrograms/day of [(imBzl)-D-His6-Pro9-NEt]-LHRH (LHRH-A), a potent agonist of LHRH. After an initial increase, serum testosterone levels declined to 10% of pretreatment levels in three monkeys and the response to electroejaculation was lost. There was a decrease in testicular volume. Androgen replacement in the form of subcutaneous SILASTIC implants releasing 7 alpha-methyl-19-nor-testosterone acetate led to a restoration of ejaculatory response and the electroejaculates were devoid of spermatozoa. Under this treatment regimen (100 micrograms LHRH-A + 100 micrograms androgen daily), azoospermia was essentially maintained in the three monkeys for about 8 months. Withdrawal of LHRH-A and androgen treatment led to a complete restoration of testicular function. Serum testosterone returned to control levels and spermatozoa reappeared in the ejaculates with sperm counts reaching the normal range. Testicular volumes showed a gradual increase. These results indicate that continuous administration of an LHRH agonist together with an androgen can induce an extended period of azoospermia in rhesus monkeys. These results also show that after prolonged suppression (more than one year) of testicular function complete recovery occurs after cessation of treatment.

Plasma levels of levonorgestrel and free levonorgestrel index in women using NORPLANT implants or two covered rods (NORPLANT-2)

Plasma levels of levonorgestrel, sex hormone binding globulin (SHBG) and estradiol were studied during four years in 283 healthy women using either NORPLANT implants or two covered rods (NORPLANT-2). The women were randomized to use either type of implant. Both implant systems have previously been shown to have similar release rates of levonorgestrel. In both groups plasma levels of levonorgestrel decreased throughout the study, and there were no statistically significant differences between the two groups in mean plasma levels of levonorgestrel. During the study 8 women became pregnant. All pregnancies but one occurred after 35 months of implant use and only in women using the covered rods. No significant differences were seen between the women who became pregnant and the rest of the group using two covered rods with respect to plasma levels of levonorgestrel. SHBG capacity tended to be somewhat higher in women using the two covered rods. As levonorgestrel is to a great extent bound to SHBG, and in that form not biologically active, a "free levonorgestrel index" was calculated as a ratio between levonorgestrel and SHBG. This index was significantly lower in users of two covered rods than in users of NORPLANT implants at 1, 12 and 48 months of use. Women who became pregnant had significantly lower "free levonorgestrel index" than had the rest of the group. It is postulated that the difference in "free levonorgestrel index" between users of the two implant systems reflect differences in release rate, the covered rods having a lower release rate of levonorgestrel than NORPLANT throughout the observation period. It is concluded that "free levonorgestrel index" is a better parameter than levonorgestrel plasma levels to describe implant function, and to discriminate women who are at risk of pregnancy.

Androgen levels in women using Norplant implants

Plasma concentrations of sex hormone binding globulin (SHBG), testosterone, free testosterone, androstenedione (A4) and levonorgestrel were studied in 17 women before and during use of two levonorgestrel covered rods resulting in identical plasma concentrations of levonorgestrel as Norplant implants. There was a highly significant decrease in SHBG during treatment. Total testosterone and A4 also decreased significantly. Free testosterone remained unchanged. Diurnal variations were found to occur for A4, total and free testosterone, but not for SHBG or levonorgestrel. Moreover, plasma concentrations of testosterone, free testosterone, levonorgestrel and SHBG were measured in a second group of 88 women participating in a clinical study on Norplant implants, who at the one year follow-up visit either denied or claimed to have developed increased facial acne during treatment. There was no difference regarding SHBG, total testosterone, free testosterone or levonorgestrel between the groups of women with and without facial acne. However, the women in the group noticing increased acne during treatment, reported significantly more often to have had acne before treatment compared to the women who did not notice increased acne during treatment. It is concluded that treatment with Norplant implants does not result in increasing plasma levels of androgens.

Enhanced metabolism of levonorgestrel during phenytoin treatment in a woman with Norplant implants

A 26-year-old woman, treated with phenytoin for 10 years because of epilepsy, had Norplant subdermal implants inserted after a legal abortion. She became pregnant again after nine months of Norplant use. Her plasma levonorgestrel (LNG) levels were followed during one month during phenytoin treatment and then later during one month after discontinuation of phenytoin. During phenytoin treatment, plasma LNG levels were markedly below the levels found in healthy women with Norplant. There was a pronounced, statistically significant increase in plasma LNG levels after discontinuation of phenytoin. The plasma levels of sex hormone binding globulin were markedly above those found in normal healthy women during treatment with phenytoin and decreased significantly after cessation of phenytoin. The effects on the pharmacokinetics of LNG were reflected by effects on the menstrual cycle. During phenytoin treatment, the woman had regular ovulatory menstrual cycles. After cessation of phenytoin, her cycles became irregular and during the study period of one month, no signs of ovulation were found. It is concluded that treatment with phenytoin during use of Norplant subdermal implants enhances the metabolism of LNG to an extent where the contraceptive efficacy is endangered.

Abnormal endocrine profile among women with confirmed or presumed ovulation during long-term Norplant use

FSH, LH, estradiol and progesterone were serially assayed during 8 cycles of six subjects using six subdermal implants releasing levonorgestrel (NORPLANT) for a period of 2 to 6 years. All 8 cycles studied had a very low LH peak and a low or nonexistent FSH peak as compared to 8 control cycles. The mean LH peak for NORPLANT users was 33.9 mIU/ml as compared to 142 mIU/ml in the control group; and FSH was 13.0 mIU/ml as compared to 31.3 mIU/ml in controls. A subsequent rise in progesterone was observed in the 8 cycles studied, but the mean mid-luteal levels were significantly lower than in controls (9.0 ng/ml vs. 15.6 ng/ml). No differences were observed in the estradiol curve. Two of the subjects using NORPLANT had a laparotomy performed on days 17 and 20 of the cycle, for surgical sterilization purposes. A distinctive corpus luteum with a stigma was observed. Our results indicate that women under prolonged use of NORPLANT do not have normal endocrine cycles, even though they may ovulate. It is doubtful however, that these ovulatory cycles can be fertile under the abnormal endocrine conditions found in our subjects. In addition to the possible effect of luteal insufficiency, the normal maturation of the oocyte may be impaired.

Cholesterol and HDL-cholesterol values in women during use of subdermal implants releasing levonorgestrel

Plasma concentrations of cholesterol, HDL-cholesterol, and levonorgestrel were determined in two groups of women using levonorgestrel-releasing subdermal implants. One group used six capsules (NORPLANT)*; the other six covered rods. Plasma concentrations of levonorgestrel among NORPLANT users averaged 700 pg/ml in the first two weeks of use, decreased to 300 pg/ml at 8 weeks, and to about 230 pg/ml by 50 weeks. Concentrations among covered rod users were 1.4 to 1.7 times higher at comparable time periods. Total serum cholesterol and HDL-cholesterol were decreased as compared with controls at all sampling intervals during the 114 weeks of the trial, although the differences did not meet tests of significance at all time periods. Decreases during the test period were of the order of 10 percent, except for total cholesterol among covered rod users where the decrease was less. Cholesterol to HDL-cholesterol ratios did not differ significantly from control values at any sampling period.

Fertility regulation in nursing women: VII. Influence of NORPLANT levonorgestrel implants upon lactation and infant growth

The objective of this study was to test the influence of NORPLANT implants upon lactation and infant growth. The results obtained during the first postpartum year are reported. One-hundred women were enrolled in the implant group. The control group was formed by 100 women who received a Copper T IUD. Treatments were administered at day 55 +/- 3. At admission all subjects were in exclusive breastfeeding with an adequate weight increase of the infant. No significant differences were found between the treated and control groups in the percentage of women in full nursing at different postpartum intervals, except for the 12th month postpartum where a lower percentage of cases from the NORPLANT group was in the full nursing category. No difference was found in the time of weaning. The infants showed a normal weight gain rate in both groups although the girls from the NORPLANT group showed a significantly lower daily weight increase during the 4th month than the girls from the IUD group. No pregnancies were diagnosed. No women asked for implant removal during the first year. No serious side effects related to treatment were detected. Bleeding irregularities were rare during breastfeeding which is in contrast with what occurs in non-nursing women treated with NORPLANT implants. Levonorgestrel concentrations found in milk were variable and individual values ranged from 23 to 311 pg/ml. The dose received by the infant can be estimated around 15 to 18 ng/Kg/day during the first month of treatment when the higher plasma values of levonorgestrel are observed. These levels is conjunction with the clinical observations reported here minimize the potential problems associated with levonorgestrel transference through maternal milk. Nevertheless, long-term studies are required to settle this matter and until more information is available, NORPLANT implant use in lactating women should be limited to cases who require a highly effective contraceptive method and where non-hormonal methods of similar effectiveness are contraindicated or unacceptable.

Plasma levonorgestrel and progesterone levels in women treated with silastic covered rods containing levonorgestrel

Levonorgestrel and progesterone plasma levels were measured in women bearing levonorgestrel subdermal implants. Two groups using four or six levonorgestrel covered rods and one group of non-hormonal contraceptors were compared. Blood samples were drawn twice a week for six consecutive weeks at different intervals after treatment administration. The mean levonorgestrel levels (mean +/- S.D.) observed in the four rods group was .49 +/- .13 ng/ml in the first year and decreased to .34 +/- .06 in the fifth year of treatment. The mean values observed in the six rods group were .70 +/- .15 ng/ml in the second year and .43 +/- .11 in the sixth year. The levonorgestrel plasma levels were slightly above those found with Norplantr implants in the four rods group and well above it in the six rod group. The highest plasma progesterone value found in each sampling period was above 9 nmol/l in 7 (14%) out of 50 subjects in the four rods group, in 2 (4.3%) out of 47 subjects in the six rods group and in all the 49 control women. In 4 out of the 7 subjects from the 4 rods group and in the two subjects from the 6 rods group, the highest progesterone value was preceded and followed by values lower than 6 nmol/l. It was concluded that the progesterone levels were seldom compatible with the occurrence of ovulation in women treated with four or six levonorgestrel covered rods which release an estimated daily dose of 70 and 105 micrograms, respectively.

Clinical chemistry in women treated with six levonorgestrel covered rods or with a copper IUD

A group of women treated with six levonorgestrel covered rods participated in a study on general chemistry and blood levels of selected hormones at treatment months 20 and 65. A comparable group of Copper T users served as control. Parameters analyzed were the SMA 12 chemistry profile, estradiol, testosterone, cortisol, T3, T4 and TSH. Samples from treated and control subjects were drawn within the same calendar period and were run simultaneously for the assay of each parameter. The values observed were within the normal limits. Significantly higher values of total protein and albumin and lower levels of estradiol and testosterone were found among implant users when compared to the control group. The results suggests little or no metabolic changes in users of six levonorgestrel covered rods which release a daily dose of approximately 105 micrograms.

Contraception with long-acting subdermal implants. A five-year clinical trial with Silastic covered rod implants containing levonorgestrel. The International Committee for Contraception Research (ICCR) of the Population Council

A total of 189 women volunteered to accept subdermal implants for contraception. The implants were "covered rods", consisting of a core rod containing equal parts by weight of levonorgestrel and polydimethylsiloxane and sealed inside a thin-walled tube of Silastic tubing with medical adhesive. In one study 78 women used 4 3cm rods (study 07) and in the other 111 women used 6 3cm rods. In 5 years of use there were no pregnancies in either group. Terminations because of menstrual problems were twice as frequent among the 4-rod users than among users of the 6 rods. Menstrual pattern analysis is presented for the two rod regimens and compared with the previously reported patterns for the 6-capsule regimen (NORPLANT). Long--term in vivo release rates are also presented.

Long-term experience with Norplant contraceptive implants in Finland

Silastic implants containing the progestin, levonorgestrel, were tested as a long-term contraceptive system in 124 women. During five years of use no accidental pregnancy occurred. The first year continuation rate was 90% and the five-year continuation rate was 54%, including terminations for wish to become pregnant. The medically relevant continuation rate was 68% after five years. Menstrual irregularities were the most frequent reason for termination, but only in the first two years. 70% of the terminations for that reason occurred during the first two years. Terminations for other steroid-related reasons were infrequent. The follow-up will continue up to the end of the seventh year. Seven of seventeen women who requested removal of the implants because they wanted to become pregnant conceived during the first two cycles and only three were not pregnant one year after removal.