Cholesterol-lowering effect of spreads enriched with microcrystalline plant sterols in hypercholesterolemic subjects.

BACKGROUND: Plant sterols have been shown to reduce serum lipid concentrations. The effectiveness is highly dependent on the physical state of the plant sterols. By means of a new crystallizing method, plant sterols can be added into dietary fats and oils homogeneously. In this fat ingredient, plant sterols are in a microcrystalline form. AIMS OF THE STUDY: We investigated the cholesterol-lowering effect and possible side effects of vegetable oil-based spreads fortified with two different doses of microcrystalline plant sterols. METHODS: This double-blind randomized, placebo-controlled study consisted of a 6-wk run-in and a 6-month experimental period. During the run-in period, all 155 hypercholesterolemic subjects received rapeseed oil-based control spread. In the beginning of the experimental period subjects were randomly assigned into one of three experimental groups. The control group continued to use control spread, and the two test groups used spreads with added plant sterols of either 1.5 g/d or 3.0 g/d. The subjects consumed test spreads as a part of their normal diet without any restrictions in lifestyle and diet. RESULTS: Plasma total- and LDL-cholesterol concentrations were significantly reduced by 7.5-11.6% (0.46-0.62 mmol/1) in groups consuming margarine enriched with free plant sterols, compared with the control group. The effects were similar between the two groups consuming either 1.5g or 3.0 g plant sterols per day. No effect on HDL-cholesterol or triacylglycerol concentrations occurred. The test spreads did not induce any adverse effects in blood clinical chemistry, hematology or decreases in serum concentrations of lipid soluble vitamins. CONCLUSIONS: Microcrystalline plant sterols are effective in lowering serum total- and LDL-cholesterol concentrations without obvious side effects. The daily dose of 1.5 g plant sterols is enough to reach the maximum effect.

Milk and plasma concentrations of the progestin ST-1435 in women treated parenterally with ST-1435.

A subcutaneous contraceptive capsule releasing progestin ST-1435 was used by 6 breast-feeding women. One to three paired milk and plasma samples were collected over a one-month period and the concentrations of ST-1435 were determined by radioimmunoassay. An improved and sensitive method for determination of ST-1435 in milk was developed. A column chromatographic purification of milk prior to radioimmunoassay decreased the blank and improved sensitivity. The average plasma concentration of ST-1435 was 62 +/- 20 pg/ml (mean +/- SD). The average milk concentration of ST-1435 was 38 pg/ml (ranging from 7 to 73 pg/ml), while the average milk to plasma ratio was 0.60 (ranging from 0.25 to 0.91). There was a significant correlation between ST-1435 concentrations in breast milk and plasma, indicating that the concentration in plasma is the major determinant for the amount of ST-1435 excreted into milk. Since studies with this drug have shown good contraceptive efficacy and low bioavailability after oral intake, ST-1435 is a good candidate for lactational contraception.

Metabolism and serum binding of RU 486 in women after various single doses.

The metabolism of RU 486 was studied in female volunteers following a single oral administration of 100, 400, 600 or 800 mg of RU 486. The serum concentrations of RU 486 were generally not affected by the dose within the range examined and they stayed at micromolar concentrations during the 48 h studied. RU 486 was metabolized extensively in a dose-dependent manner by two-step demethylation, and by hydroxylation. Serum levels of the monodemethylated metabolite always exceeded those of RU 486. The concentrations of the didemethylated and hydroxylated metabolites equalled or exceeded those of RU 486 when the ingested dose was 400 mg or more. Monodemethylation and hydroxylation were rapid high-capacity reactions, whereas didemethylation was a lower-capacity reaction. In each group of different dosage, positive correlations were found between the individual mean alpha 1-acid glycoprotein (AAG) concentrations and the peak concentration of RU 486 measured at 1-2 h, versus the plateau concentration of RU 486 measured at 6 h. The in-vitro studies showed that the specific serum transport protein of RU 486, AAG, was saturated by RU 486 concentrations exceeding 2.5 microM. In serum at 40 nM and 2.5 microM RU 486 concentrations, 2.7% and 2.4%, respectively, of [3H]RU 486 was not protein bound. Purified AAG in phosphate buffer was able to bind [3H]RU 486 in a similar manner to that of serum. Thus our results suggest that AAG regulates in part the serum concentrations of RU 486, and RU 486 exceeding the specific serum transport capacity is effectively metabolized.

Sustained intrauterine release of levonorgestrel over five years.

Two models of levonorgestrel-releasing intrauterine devices were studied. Model A was designed to deliver 20 micrograms/day, and model B was designed to deliver 30 micrograms/day. Plasma concentrations of levonorgestrel were determined in blood samples taken from women who used the levonorgestrel-releasing intrauterine devices (IUDs) and who participated in a clinical trial for more than 5 years. During clinical studies IUDs have been removed for various reasons between 8 and 40 months after insertion. The rate of release of levonorgestrel from the IUDs was calculated by determining the remaining amount of levonorgestrel. Plasma concentrations of levonorgestrel ranged between a mean +/- standard deviation (SD) concentration of 166 +/- 75 pg/ml and 131 +/- 32 pg/ml for the first 18 months of use and between 101 +/- 37 pg/ml and 74 +/- 15 pg/ml at 24 and 60 months after insertion of the IUD. The plasma concentrations from 24 months through 60 months were significantly lower than concentrations measured during initial months of IUD use, but not between the two devices. There was a strong correlation between the time of use and the amount of levonorgestrel lost from the IUDs. The calculated mean daily release of levonorgestrel was 17.6 micrograms for model A and 22.2 micrograms for model B. This gives a calculated lifetime of more than 6 years for a levonorgestrel-releasing IUD.

PIP: 2 models of levonorgestrel-releasing IUDs were studied. Model A was designed to deliver 20 mcg/day and model B 30 mcg/day. Plasma concentrations of levonorgestrel were determined in blood samples taken from who had used the levonorgestrel-releasing IUDs and who had participated in a clinical trial for more than 5 years. During clinical studies, IUDs have been removed for various reasons between 8-40 months after insertion. The rate of release of levonorgestrel from the IUDs was calculated by determining the remaining amount of levonorgestrel. Plasma concentrations of levonorgestrel ranged between a mean +or- standard deviation concentration of 166 +or- 75 pg/ml and 131 +or- 32 pg/ml for the 1st 18 months of use and between 101 +or- 37 pg/ml and 74 +or- 15 pg/ml at 24 and 60 months after IUD insertion. Plasma concentrations from 24 to 60 months were significantly lower than concentrations measured during the initial months of IUD use, but not between the 2 devices. There was a strong correlation between the time of use and the amount of levonorgestrel lost from the IUDs. The calculated mean daily release of levonorgestrel was 17.6 mcg for model A and 22.2 mcg for model B. This gives a calculated lifetime of more than 6 years for a levonorgestrel-releasing IUD.

Concentration-dependent mechanisms of ovulation inhibition by the progestin ST-1435.

We summarize the hormonal profiles of women at different stages of inhibition of ovarian function during sustained-release subcutaneous treatment with a progestin, ST-1435. In the highest release group of ST-1435, a decrease in the luteinizing hormone (LH)follicle-stimulating hormone (FSH) ratio was found; and in spite of follicular phase levels of plasma FSH, inhibition of folliculogenesis, as judged by plasma estradiol (E2) concentrations below 60 pg/ml, occurred during the entire treatment period of 230 days. This may be indicative of a direct action of ST-1435 on the ovaries. When the average plasma concentration of ST-1435 decreased below 100 pg/ml, follicle development had started in most of the study subjects. At that time, the LH/FSH ratio had normalized to that found during the follicular phase of the normal menstrual cycle. In spite of the E2 rise during follicular development, no midcycle gonadotropin surges or subsequent elevations in plasma progesterone concentrations were found, thus indicating that the positive feedback action of E2 on gonadotropins was blocked by this progestin. We infer that the mechanism of inhibition of ovulation by sustained parenteral treatment with the progestin ST-1435 is concentration dependent, in such a manner that lower plasma concentrations of ST-1435 act on the hypothalamus and/or pituitary, whereas at higher plasma concentrations of ST-1435, a direct effect on the ovaries is also achieved.

Immediate postabortal contraception with Norplant: levonorgestrel, gonadotropin, estradiol, and progesterone levels over two postabortal months and return of fertility after removal of Norplant capsules.

Six Silastic levonorgestrel-releasing capsules, Norplant, were introduced subcutaneously into the ventral aspect of the left forearm or upper arm of thirteen patients immediately after first trimester pregnancy termination. Blood samples were taken twice a week over two months after abortion and from one subject over one month after removal of Norplant capsules. Plasma concentrations of levonorgestrel were measured by radioimmunoassay and the effects of treatment on pituitary and ovarian function were determined by assaying plasma concentrations of LH, FSH, estradiol and progesterone. If removal of Norplant capsules took place because of planning pregnancy, the subjects were asked to inform us if they had become pregnant. During the first month after abortion the mean levonorgestrel concentration (489 pg/ml) was statistically significantly higher than during the second month (237 pg/ml). The mean estradiol values fell to prefollicular levels within four days, remaining a little suppressed. The mean progesterone concentrations were below 2 ng/ml three days after abortion. Three subjects had a transient increase in plasma progesterone concentrations nine days after abortion. Thereafter no ovulatory progesterone concentrations were seen. The LH concentrations ranged within normal values of the follicular phase and FSH values were just beneath the lower limit of follicular phase FSH values, apart from a few peaks, indicating mild suppression. After removal of Norplant capsules, progesterone concentrations increased to ovulatory levels fifteen days after removal. The Norplant capsules were removed from two subjects because of planning pregnancy and they delivered healthy babies 9.5 and 12.5 months after removal.

Pharmacokinetic observations on ST-1435 administered subcutaneously and intravaginally.

Plasma levels of ST-1435 were determined by radioimmunoassay in 36 women and three men during treatment with subdermal capsules releasing ST-1435. The total lengths of the capsules used were 180 mm, 90 mm, 30 mm, 15 mm and 7.5 mm. A linear correlation between the mean plasma concentrations of ST-1435 and capsule length was found during the treatment period studied. However, great interindividual variation in plasma levels of ST-1435 between study subjects having similar capsules was observed. In comparison with the mean plasma concentrations in the initial months, only less than half of these plasma concentrations of ST-1435 were measured after six months of treatment, which indicates a short lifetime for this contraceptive system. In two women the disappearance of ST-1435 from the circulation was studied by measuring ST-1435 concentrations in the plasma after removal of a contraceptive vaginal ring (CVR) releasing ST-1435. Triphasic disappearance curves of ST-1435 were found, with half-lives 0.7-1.0 h, 3.1-4.0 h, and 10.7.3-11.8 h.

Intestinal absorption of ST-1435 in rats.

The intestinal absorption of a 19-norprogesterone (ST-1435) was studied in rats after an oral dose of 5 mg ST-1435/kg body weight. Blood samples were collected simultaneously from the portal vein and by cardiac puncture. Plasma ST-1435 concentrations were measured from the samples by radioimmunoassay (RIA). Chromatographic purification of ST-1435 in rat plasma revealed a metabolite cross-reacting in the RIA. A peak concentration of 240 ng ST-1435/ml was found in portal plasma 75 minutes after administration, indicating that the steroid is well absorbed from the small intestine. However, in spite of the relatively high dose used, the plasma concentrations of ST-1435 in the systemic circulation remained low and of short duration. Thus, it seems that ST-1435 in hepatic portal blood is extensively taken-up and metabolized by the liver, resulting in low plasma concentrations of ST-1435 in the systemic circulation when the steroid is administered orally. This is also supported by the observation that higher metabolite levels were found in systemic plasma than in portal plasma during the first 90 minutes after administration. This pronounced first-pass effect may also explain why in women oral administration of ST-1435 has failed to result in any biological effect.

Intracervical release of ST-1435 for contraception.

Seven women used an ST-1435-releasing intracervical contraceptive device (ST-ICD), inserted immediately after the cessation of menstrual bleeding. Patterns of bleeding and clinical performance were evaluated and plasma concentrations of ST-1435, estradiol, progesterone and gonadotropins were measured by radioimmunoassays. The results of ten months of treatment are presented. There were no uniform patterns of bleeding. No hormonal side-effects were registered. The plasma concentration of ST-1435 reached 100 pg/ml within two hours after insertion of an ST-ICD. No ovulations occurred during the initial three months of treatment. A rapid decline in the plasma concentrations of ST-1435 was observed; during the tenth month the concentration of ST-1435 was under the sensitivity of the radioimmunoassay of ST-1435. Hence, the release of ST-1435 from Silastic was too rapid for long-acting contraceptive purposes.

Pituitary and ovarian function and clinical performance during the use of a levonorgestrel-releasing intracervical contraceptive device.

A levonorgestrel-releasing intracervical device (ICD) was inserted postmenstrually to twenty-one voluntary women. Eight subjects gave blood samples twice a week during the initial three months of use of the ICD and during the seventh and twelfth months of use. Clinical performance was studied; plasma concentrations of levonorgestrel were measured by radioimmunoassay and the effects of the treatment on pituitary and ovarian function were determined by assaying plasma concentrations of LH, FSH, estradiol and progesterone. The results of the first year are presented. Dysmenorrhea, menstrual flow and the number of days of bleeding decreased during the first treatment year. Three spontaneous expulsions occurred; two at the very beginning of the treatment and one after six months of use. Side-effects were few. The plasma level of levonorgestrel remained fairly constant during the observation time of 12 months. Thirty-one of the 36 cycles were ovulatory as judged by plasma progesterone elevations. No pregnancies occurred during the study period of one year.

Ovarian function in amenorrheic and menstruating users of a levonorgestrel-releasing intrauterine device.

The ovarian function of 20 healthy users of a levonorgestrel-releasing intrauterine device was studied by measurements of plasma estradiol, progesterone, and levonorgestrel concentrations. Eight subjects were amenorrheic, and 12 had regular menstrual bleeding. Seventy-five percent of the subjects in both groups had ovulatory cycles. There was no difference between the mean levonorgestrel concentrations in the amenorrheic and regularly menstruating subjects. Estradiol function was undisturbed in the amenorrheic subjects with ovulatory cycles. The effect of levonorgestrel as a cause of amenorrhea is thought to be mainly of local nature. The intrauterine administration of levonorgestrel had only an occasional and weak effect on ovarian function.

Postabortal contraception with norethisterone enanthate injections.

Intramuscular injection of 200 mg norethisterone enanthate (NET-EN) was given to five women on the day of first trimester abortion. The injection was repeated twice at eight-week intervals, and thereafter at twelve-week intervals for one year. Plasma samples were collected for FSH, LH/hCG, estradiol, progesterone and norethisterone (NET) determinations. NET-EN did not affect the elimination of hCG, estradiol or progesterone. Plasma NET concentrations reached a peak (5.5-11 ng/ml) in about ten days after the injection and declined constantly thereafter, to levels of 0.18-0.64 ng/ml at 8 weeks after the injection. NET-EN postponed the increase in FSH secretion until 17-20 days after the injection, i.e. until plasma NET concentrations fell below 3 ng/ml. In three out of five women some follicular activity was present 5 weeks after NET-EN injection as evidenced by increased plasma estradiol concentrations. No ovulation occurred within 8 weeks after NET-EN injection, as judged by low progesterone values. There was a definite accumulation of NET during the first six months, when NET-EN injections were given at eight-week intervals. Mean plasma NET concentrations increased from 0.34 ng/ml at eight weeks to 0.78 ng/ml at 24 weeks. When the injection interval was increased to twelve weeks, the plasma NET concentrations prior to the next injection started to decrease. This was accompanied by increased follicular activity, culminating with one ovulation observed. It is concluded that in this population of women, an injection interval of less than twelve weeks is needed for ovulation inhibition.

Distribution and percentages of non-protein bound contraceptive steroids in human serum.

PIP: It has been shown that albumin bound steroids are taken up by the rat brain in addition to nonprotein bound steroids and it has also been suggested that cortisol binding globulin (CBG) may facilitate progesterone uptake by the rat uterus but not the brain. Recently serum sex-hormone binding globulin (SHBG) has been identified in the cytoplasm of sex steroid target cells. Thus the distribution of synthetic steroids between various protein bound and nonprotein bound components in serum may influence their bioavailability at different target tissues. The authors employed a newly developed technique, centrifugal ultrafiltration-dialysis. The results showed that there are no differences in percentages of nonprotein bound ethinyl estradiol (EE2), and cyproterone acetate (CA) with respect to sex or serum SHBG and CBG binding capacities. However serum percentages of nonprotein bound norethisterone (NET) (p0.05) are significantly lower in women than in men. Also the percentages of nonprotein bound NET and D-norgestrel are both very much lower (p0.001) in serum from pregnant women when compared to nonpregnant women. These differences appear to be inversely related to serum SHBG binding capacity. The percentages of nonprotein bound NET and D-norgestrel in heat treated serum from men and nonpregnant women are identical and largely represent the contribution of albumin binding alone. In addition heat labile binding proteins do not appear to influence the percentages of nonprotein bound EE2 and CA and it can be inferred that EE2 and CA are almost exclusively bound by albumin in native serum; 98.5% of EE2 and 93% of CA are bound to albumin. In contrast the percentages of nonprotein bound NET and D-norgestrel in native serum are inversely related to SHBG binding capacity. This data indicate that the nonprotein bound and albumin bound factors of NET and D-norgestrel may vary by as much as 2-3 fold between women who are known to have subnormal or supranormal levels of serum SHBG binding capacity and it is suggested that measurements of serum SHBG binding capacity may provide a method of assessing the lowest effective dose of these 2 progestins in individual subjects to help reduce side effects associated with their use. Future studies should address the effect of serum steroid concentrations on the actual nonprotein bound serum concentrations and distribution of these progestins.^ieng