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Precocious puberty associated with neurofibromatosis and optic gliomas. Treatment with luteinizing hormone releasing hormone analogue.

Seven children with central precocious puberty and either neurofibromatosis and/or optic gliomas were referred to the National Institutes of Health, Bethesda, Md, for evaluation and treatment with the long-acting luteinizing hormone releasing hormone analogue (LHRHa) D-Trp6-Pro9-NEt-LHRH. Only six of the seven children chose to receive treatment. Four children presented with neurofibromatosis, three of whom also had optic gliomas; the remaining three children had isolated optic gliomas, without other neurocutaneous stigmas. All had central precocious puberty mediated by activation of the hypothalamic-pituitary-gonadal axis. Six months of LHRHa therapy caused suppression of gonadotropin and sex steroid levels, stabilization or regression of secondary sexual characteristics, and decreases in growth velocity and the rate of bone age maturation. We conclude that LHRHa therapy is effective in the treatment of central precocious puberty secondary to neurofibromatosis and/or optic gliomas.

17-alpha-Hydroxyprogesterone

Two partial remissions induced by an LHRH analogue in two postmenopausal women with metastatic breast cancer.

We report two cases of metastatic breast cancer occurring in two postmenopausal women. Treatment with a luteinizing hormone-releasing hormone (LHRH) analogue, D-TRP6-LHRH, induced partial remission. The blood levels of the follicle stimulating hormone (FSH) and luteinizing hormone (LH) fell sharply under treatment, but the levels of estradiol, estriol, and estrone did not change significantly. We also described the putative mechanisms of action of the LHRH analog.

Aged

Inhibitory effects of analogs of luteinizing hormone-releasing hormone and somatostatin on pancreatic cancers in hamsters. Events that accompany tumor regression.

Syrian golden hamsters bearing N-nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic carcinomas were treated for 2 months with the delayed delivery systems of the agonist D-Trp-6-LH-RH (microcapsules releasing 25 micrograms/day for 30 days), the somatostatin analog RC-160 (the microcapsules liberating 48.2 micrograms/day for 30 days), or with the combination of these two analogues. The increase in the dose of RC-160 was possible in view of the lack of toxicity of this analog. This higher dose of RC-160 exerted a greater suppressive effect on pancreatic cancers than the regimens previously used (5-25 micrograms/day). RC-160, D-Trp-6-LH-RH, and their combination reduced the number of pancreatic carcinomas and significantly inhibited tumor growth as compared with the controls. The combination had the strongest tumor-inhibitory effect and reduced tumor weight by 85% as compared with controls. Both the light and electron microscopic analysis of the tumors showed that the inhibitory effect was due to the enhancement of apoptosis (programmed cell death) of tumor cells. Insulin-like growth factor (IGF-I) receptors were detected immunohistochemically in the untreated tumors and their number decreased after the treatment with the analogues. Binding of D-Trp-6-LH-RH and RC-160 to tumor cells was shown immunohistochemically and receptors to these analogues and IGF-I were also determined biochemically by radioligand titration. Treatment with D-Trp-6-LH-RH and RC-160 decreased the binding capacity of receptors for D-Trp-6-LH-RH and IGF-I, producing down-regulation of these receptors. This suggests that pancreatic tumor cells with receptors to these peptides are sensitive to the treatment. This work reinforces the view that the combination of high doses of somatostatin analog RC-160 with LH-RH agonists or antagonists should be considered for the development of a new hormonal therapy for ductal pancreatic cancers.

Amino Acid Sequence

An efficient algorithm for sequencing peptides using fast atom bombardment mass spectral data.

An efficient algorithm is described for sequencing peptides from sequence ions appearing in fast atom bombardment (FAB) and FAB tandem mass spectra. The following features are incorporated in the algorithm. The members of the set of sequence ions are represented by all possible combinations of N- and C-terminal fragment ions. From the known N- and C-terminating groups and molecular weight (MW) of the peptide, the sequence ions are mathematically re-expressed as N-terminal residue ions and arranged in ascending order. The peptide sequence is computed, in a stepwise iterative procedure, from the mass differences between the mathematically re-expressed N-terminal residue ions and the predicted peptide subsequences for the neighboring ions of lower mass. These mass differences correspond to combinations of known amino acid residues which have previously been computed and tabulated, based upon the FAB fragmentation rules for peptides. The algorithm was successfully applied to sequence the following peptides from their respective FAB or FAB tandem mass spectrum: decapeptyl (MW 1310), angiotensin II (MW 1045), and two 'unknown' peptides (MW 1227 and 1485, respectively). Two criteria used to predict the correct peptide sequence from among many possibilities are the minimum number of amino acid residues and the maximum fragmentation probability per amino acid residue.

Algorithms

Effect of D-tryptophan-6-luteinizing hormone-releasing hormone on the tumoral growth and plasma sex steroid levels in cirrhotic patients with hepatocellular carcinoma.

Certain evidence suggests androgen dependence of hepatocellular carcinoma in cirrhotic patients. Consequently, it was postulated that antiandrogen therapy might be effective in the treatment of hepatocellular carcinoma. D-Tryptophan-6-luteinizing hormone-releasing hormone is a potent agonist analog of luteinizing hormone-releasing hormone which, when chronically administered, inhibits the pituitary gonadal axis and testicular androgen secretion in man. We studied the effects of D-tryptophan-6-luteinizing hormone-releasing hormone on tumoral growth in 17 male cirrhotic patients with hepatocellular carcinoma. After 3 to 6 months of therapy, no tumoral response was observed. Furthermore, measurements of plasma levels of testosterone, dihydrotestosterone, androstenedione, estradiol, estrone and sex hormone-binding globulin were performed before and 3 months after initiation of the antiandrogenic treatment. Before treatment, hypoandrogenism and hyperestrogenism were present; D-tryptophan-6-luteinizing hormone-releasing hormone induced a fall in plasma testosterone and dihydrotestosterone levels. Only a moderate decrease in estradiol and no modification of plasma estrone and sex hormone-binding globulin were found, indicating that the hyperestrogenemia of cirrhotic patients could be attributed to an increase in peripheral aromatization of androgens of adrenal origin. The inability of D-tryptophan-6-luteinizing hormone-releasing hormone to reduce the growth of hepatocellular carcinoma is not totally in disagreement with the concept of androgen dependence of hepatocellular carcinoma since D-tryptophan-6-luteinizing hormone-releasing hormone does not inhibit the production of androgens of adrenal origin.

Aged

LH-RH agonists and antagonists.

Large doses of stimulatory analogues of luteinizing hormone-releasing hormone (LH-RH) caused paradoxical antifertility effects. These effects are being utilized for the possible development of contraceptive methods. Several inhibitory analogues of LH-RH have been tested in men and women and shown to be active. The synthetic approach based on inhibitory analogues of LH-RH has been proven to be feasible for development of new methods of birth control. Continued research and testing along these lines may lead to the development of contraceptives based on inhibitory analogues of LH-RH that could be conveniently applied as a nasal spray and could be free of undesirable side effects.

Animals

Prolonged suppression of plasma LH levels in male rats after a single injection of an LH-RH agonist in poly(DL-lactide-co-glycolide) microcapsules.

The authors have examined the effects of a subcutaneous injection of the LH-RH agonist D-Trp6-LH-RH formulated in biodegradable poly(DL-lactide-co-glycolide) microcapsules on plasma levels of D-Trp6LH-RH, LH, and PRL in adult, gonadectomized male rats. Immunoreactive D-Trp6-LH-RH was detectable in the plasma of these animals at 1, 2, 3, and 4 weeks after injection. LH concentrations were greatly reduced 1 week after administering the D-Trp6-LH-RH microcapsule, continued to decrease during the following week, and remained suppressed until the end of the study, 6 weeks after the injection. Plasma PRL levels appeared elevated 1 to 2 weeks after the injection and suppressed thereafter, but these effects were significant only in animals rendered hyperprolactinemic by transplantation of an isologous pituitary under the renal capsule. These results demonstrate that an LH-RH agonist formulated in biodegradable microcapsules and administered as a subcutaneous injection can exert marked biologic effects in rats for at least 6 weeks. These findings also suggest that prolonged exposure to an LH-RH agonist may first produce stimulation, followed by an inhibition of PRL release from both in situ and ectopic pituitaries.

Animals

Normal gonadal functions and fertility after 23 months of treatment of prepubertal male and female dogs with the GnRh agonist [D-Trp6, des-Gly-NH2(10)]GnRH ethylamide.

The GnRH agonist [D-Trp6, des-Gly-NH2(10)]GnRH ethylamide was administered to prepubertal male and female dogs daily for 23 months by subcutaneous injection. During GnRH agonist treatment, plasma steroid levels, namely dehydroepiandrosterone, androst-5-ene-3 beta-17 beta-diol, androstenedione, testosterone, dihydrotestosterone, 5 alpha-androstane-3 alpha, 17 beta-diol, 5 alpha-androstane, 3 beta, 17 beta-diol were markedly inhibited in male animals, whereas in female animals, the plasma concentration of DHEA and delta 5-diol were decreased. Within 2 months following cessation of therapy, all steroids increased to normal adult levels. Morphological studies reveal that treatment of male animals with the GnRH agonist is accompanied by a small volume of seminiferous tubules, Leydig cells, and prostate gland, whereas in the ovaries of female animals, there is a large number of primordial follicles, a few primary follicles, but no secondary follicles. In the pituitary gland of animals of both sexes, LH-secreting cells have high levels of glycogen particles in their cytoplasm and tend to be either of normal appearance with dilated rough endoplasmic reticulum (RER) or strongly atrophied with a dark-stained cytoplasm, a contraction of RER, and a decrease in the number of secretory granules. Reticular cells of the connective tissue also show high levels of glycogen particles. After the 14 month recovery period, spermatogenesis has a normal adult appearance, the prostate gland shows a normal secretory epithelium, and secondary follicles are easily observed in the ovary. Gonadotrophs are free of glycogen accumulation, but reticular cells continue to show an accumulation of glycogen particles in their cytoplasm. Two male and two female animals were mated after the recovery period and produced normal offspring with normal fertility. The present results indicate that GnRH agonist treatment achieves a blockade of sexual maturation and that following cessation of treatment, normal pituitary-gonadal functions resume, with apparently normal fertility and normal offspring.

Animals

Characteristics and distribution of receptors for [D-TRP6]-luteinizing hormone-releasing hormone, somatostatin, epidermal growth factor, and sex steroids in 500 biopsy samples of human breast cancer.

Binding capacities and apparent dissociation constants of receptors for [D-Trp6]-luteinizing hormone-releasing hormone [( D-Trp6]-LH-RH), somatostatin (SS-14), epidermal growth factor (EGF), and estrogen and progesterone were determined in 500 breast cancer specimens using multipoint assays. Specific binding sites greater than 10 fmol/mg cytosol protein for estrogen were found in 408 carcinomas (81.6%), and for progesterone in 340 specimens (68%). High affinity EGF receptors were present in membrane preparations from 335 samples (67%). In 260 of 500 samples (52%), two classes of [D-Trp6]-LH-RH membrane receptor sites were also detected, one class showing high affinity and low capacity, and the other class showing low affinity and high capacity; 178 biopsy samples (35.6%) exhibited binding sites for SS-14. Statistically significant inverse correlations were found between the binding capacities of estrogen and EGF receptors as well as between Bmax of progesterone and EGF receptors. Significant positive correlations were demonstrated between binding capacities of estrogen and progesterone and between Bmax of high affinity and low affinity binding sites of [D-Trp6]-LH-RH receptors. However, no correlation was found between the dissociation constants of different receptor sites in human breast cancer specimens. These results demonstrate that numerous human breast cancers, in addition to receptors for estrogen and progesterone, also show binding sites for EGF, [D-Trp6]-LH-RH and SS-14. The methods described herein permit a routine quantification of receptor sites for [D-Trp6]-LH-RH, SS-14, and EGF in membrane preparations of biopsy samples of breast cancer and can be used in conjunction with the determination of estrogen and progesterone receptors in nuclear-cytosolic extracts. The simultaneous measurements using a microanalytic approach allow the determination of peptide and steroid hormone receptors that might be involved in the response mechanisms of human breast cancer. It should be possible to correlate the levels of these receptors with clinical parameters to better identify endocrine-responsive neoplasms. This approach might be useful to guide a rational hormonal therapy in women with breast cancer.

Adult

Sonographic monitoring of LHRH analogue therapy in idiopathic precocious puberty in young girls.

Precocious puberty in young girls is defined as the development of secondary sexual characteristics and gonadal growth before 8 years of age. Approximately 60% of isosexual precocious development in girls has no organic cause and is termed idiopathic precocious puberty. Thirteen young girls with idiopathic precocious puberty were treated with LHRH analogue under a well-established protocol. Pelvic ultrasound was added to the protocol to examine ultrasound's role in supplying a morphologic parameter of suppression of the pubertal process. Initially, 11 patients had ovarian volumes greater than normal, and ovarian cysts measuring 0.5 cm to 4 cm in diameter were identified in seven patients. All 13 patients had enlarged pretreatment uteri greater than 3 cm in length. Eleven of these patients had a pubertal or adult uterine configuration. After 1 year of therapy, 11 patients had normal prepubertal ovarian volumes, and 12 of 13 patients had a decrease in ovarian volume. No demonstrable cysts were present at 1 year. Eleven had a reduction in uterine length. Nine of the 11 patients with a pubertal uterine configuration reverted to a more prepubertal-like morphology. The sonographic morphologic changes correlated well with laboratory and clinical data indicating suppression of the hypothalamic-pituitary-gonadal axis.

Child

Investigation of the combination of the agonist D-Trp-6-LH-RH and the antiandrogen flutamide in the treatment of Dunning R-3327H prostate cancer model.

The therapy for the treatment of prostate cancer and other sex-steroid-dependent tumors based on agonists of LH-RH has been made more practical and efficacious by the development of a long-acting formulation of microcapsules of D-Trp-6-LH-RH for controlled release. Antiandrogens, which neutralize the effect of endogenous androgens, have been used also in the management of prostate cancer in man. The effects of a simultaneous administration of the antiandrogen flutamide and microcapsules of the agonist D-Trp-6-LH-RH were studied in the Dunning R-3327H rat prostate adenocarcinoma model to determine whether the combination of these two drugs might inhibit tumor growth more effectively than single agents. Microcapsules of D-Trp-6-LH-RH, calculated to release a controlled dose of 25 micrograms/day for a period of 30 days were injected intramuscularly once a month. Flutamide was administered SC at a daily dose of 25 mg/kg. The therapy was started 100 days after the tumor transplantation and continued for 60 days. Tumor weights and volumes were significantly reduced in rats treated with microcapsules or flutamide alone, but the former drug inhibited tumor growth more than the latter. The combined treatment of flutamide and microcapsules significantly decreased tumor weight and volume, but did not exert a synergistic effect on tumor growth, the reduction being smaller for the combination than for the microcapsules alone. There was a significant elevation of serum testosterone, LH, and prolactin in rats treated with flutamide. On the other hand, in rats given microcapsules of D-Trp-6-LH-RH, testosterone fell to castration levels within 7 days and remained at nondetectable values, serum LH and prolactin levels being also suppressed in this group. The combined administration of microcapsules and flutamide also significantly decreased serum testosterone to nondetectable levels by day 7 and suppressed serum LH and prolactin. Our findings raise doubts of whether the daily administration of the combination of LH-RH agonist with an antiandrogen offers an advantage over the use of microcapsules of an agonist like D-Trp-6-LH-RH alone in the treatment of prostatic carcinoma.

Anilides

Treatment of advanced prostatic carcinoma with D-Trp-6-LH-RH.

Twenty patients with stage D2 prostatic carcinoma were treated for up to 18 months with D-Trp-6-LH-RH. Results of more than 3 months of treatment on these 20 patients are reported. The analog was given SC once daily at a dose of 1,000 micrograms/day. All patients had bone pain and high levels of acid and alkaline phosphatase. After the first week of D-Trp-6-LH-RH administration, major decreases in bone pain and reversal of the signs of prostatism were observed. Acid phosphatase gradually fell, achieving normal values after 12 weeks. Initial plasma testosterone was within normal limits, but during treatment with D-Trp-6-LH-RH it fell to castration levels. Resting values of PRL, GH, TSH, and cortisol did not show significant changes. After TRH, TSH increased in five patients, but five did not respond. However, at 2 and 4 months, all patients released TSH in response to TRH. Two patients died during the treatment with D-Trp-6-LH-RH despite initial subjective responses and decreases in testosterone levels. The rise in acid phosphatase levels in these two patients was accompanied by a general deterioration, suggesting that they had androgen-independent cancer. One patient who developed progressive hepatic, bone, and pulmonary metastases in spite of previous orchiectomy was also treated with the analog. Three months later his acid phosphatase levels were within normal values, and partial regression of metastases was observed. These results demonstrate that D-Trp-6-LH-RH and other LH-RH agonists can be used as an effective endocrine therapy for advanced prostate carcinoma, thereby avoiding the side effects of estrogens or the psychological impact of surgical castration.

Acid Phosphatase

Persistent blockade of the pituitary-gonadal axis in patients with prostatic carcinoma during chronic administration of D-Trp-6-LH-RH.

Forty patients with stage D2 prostatic carcinoma were treated for up to 30 months with D-Trp-6-LH-RH. The analog was given s.c. once daily at a dose of 1 mg/day for the first 7 days. Subsequently, the dose was reduced to 100 micrograms/day. In follow-up studies, 30 men continued this therapy for up to 24 months. Blood samples were taken before the injection of the analog and 1, 2, 4, and 6 hours later. Serum LH, FSH, and testosterone levels were measured by RIA every month for 2 years. The initial administration of 1 mg D-Trp-6-LH-RH caused a marked elevation of LH and FSH, which lasted more than 24 hours. However, 1 month later and throughout the therapy, the basal values of LH and FSH were below the normal range and no increase in serum gonadotropins levels was obtained after administration of the analog. Initial plasma testosterone was within normal limits, but during treatment with D-Trp-6-LH-RH it fell to castration levels, and no increases were seen during the 6 hours following the injection of the analog. These results show that chronic administration of D-Trp-6-LH-RH, at the doses used, blocks the pituitary-gonadal axis and that the escape phenomenon from the effects of the LH-RH agonists-induced blockade does not occur under our conditions in contrast to observations of Kerle et al with the I.C.I. Analog 118630 (8). The accumulated results reinforce the view that long-term therapy with agonists of LH-RH is the preferred alternative to surgical castration or therapy with estrogens in men with metastatic prostate cancer.

Acid Phosphatase

Phase II trial with D-Trp-6-LH-RH in prostatic carcinoma: comparison with other hormonal agents.

Various approaches to hormonal treatment of prostate carcinoma are discussed. Eighty-one patients with prostatic carcinoma, eight with stage B, nine with stage C, and 64 with stage D disease, were treated subcutaneously daily for 3 months with the LH-RH agonist D-Trp-6-LH-RH (Decapeptyl) in order to evaluate the incidence of remissions according to WHO recommendations for oncologic trials. The findings were compared to those obtained with other hormonal therapies of prostatic carcinoma according to the statistical method of "expected response rate" as adapted by Lee and Wesley for phase II trials. Treatment with D-Trp-6-LH-RH greatly reduced serum LH and testosterone levels without raising serum prolactin. After 1-2 weeks of therapy, there was relief of subjective symptoms and a reversal of the signs of prostatism as well as a marked decrease in bone pain. At 90 days 52 patients had complete relief of prostatism and 21 had only mild signs and symptoms. Seventy patients were experiencing no bone pain and an additional six had only mild pain. Prostatic size, evaluated by rectal examination and transabdominal ultrasonography, reverted to normal in 26.4% of patients (complete remission) and was reduced by more than 50% in an additional 17.6% (partial remission), the overall rate of complete plus partial regression of prostatic enlargement being 44%. Scans showed a major improvement of bone lesions in 14.8% of cases. This response increased to 37% after more than 6 months of follow-up. Prostatic acid phosphatase levels were decreased by more than 50% in 61% of the patients, but this test appears to be a less valid marker than the lipid-associated sialic acid (LASA). The increase in LASA before treatment and a reduction after treatment can frequently be correlated with the objective volume of the neoplasms. No flare-up of the disease was encountered, and there were no side effects except for impotence. Statistical analyses of results by the method of Lee and Wesley indicated that the incidence of complete and partial regression (CR and PR) observed with D-Trp-6-LH-RH was not significantly different from that recorded in previous studies for another LH-RH analog, Buserelin. However, CR and PR obtained with D-Trp-6-LH-RH (44%) were significantly higher than with subcapsular orchiectomy (22%). Hormonal effects and some other actions of D-Trp-6-LH-RH were compared and contrasted with those produced by castration, estrogens, antiandrogens, and progestogens.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid Phosphatase

Radioimmunoassay in blood plasma of arginine esterase: the major secretory product of dog prostate.

We have developed a radioimmunoassay to determine serum levels of arginine esterase, the major secretory product of the canine prostate. Although the antibodies recognized other related proteins in immunoblotting conditions, particularly in the pancreas, the radioimmunoassay appeared specific for arginine esterase of prostatic origin and reacted only slightly or not at all with cytosolic proteins from salivary glands, liver, skeletal muscles, and kidney. In serum samples, the sensitivity limit of the assay was about 2.5 ng per ml. The interassay and intraassay variations for serum samples that contained concentrations of arginine esterase ranging from 6 to 21 ng per ml were, respectively, 14% and 24%. Sera from 30 adult males and 14 adult females contained, respectively, 71 +/- 9 and 5.3 +/- 0.4 ng per ml. In a group of 12 dogs treated daily for 36-39 days with 50 micrograms of D-Trp6-luteinizing hormone-releasing hormone ethylamide, the concentrations of arginine esterase in the serum decreased progressively and became identical with those observed in the females. These results constitute the first evidence for the presence of a serum marker of the normal prostate in an experimental model. It should be particularly useful to test the effects of various agents on the prostate.

Animals

Histological findings in the rat prostate cancer model during treatment with a luteinizing hormone-releasing hormone agonist and novantrone.

Morphological changes produced by the treatment with the D-tryptophan-6 analog of luteinizing hormone-releasing hormone (D-Trp-6-LH-RH) and mitoxantrone (novantrone) were studied in the Dunning R3327H rat prostate cancer model. Microcapsules of D-Trp-6-LH-RH, calculated to release a controlled dose of 25 micrograms/day, were injected intramuscularly once a month. Novantrone (0.25 mg/kg body weight) was injected intravenously once every 3 weeks. The pathology of tumors was studied in two experiments. In the first experiment, the treatment was started 135 days after tumor transplantation, and the therapy was continued for 105 days. In the second experiment, the treatment was initiated 45 days after tumor transplantation, and was carried on for 70 days. The rats were divided into four groups: 1) untreated control, 2) microcapsule-injected, 3) novantrone-injected, and 4) combination of microcapsules and novantrone-injected. In both experiments, similar results were obtained, which included significant reduction in the tumor volume and weight, a very striking decrease in the number of epithelial tumoral cells with atrophy of the glandular epithelium, and an increase in the stromal connective tissue. All these changes were more prominent in the group treated with the combination of microcapsules and novantrone than in the groups treated with microcapsules or novantrone alone. Pathological results support the view that combined therapy may be more efficacious than the treatment with single agents.

Adenocarcinoma

Long-term results with a long-acting formulation of D-TRP-6 LH-RH in patients with prostate cancer: an Italian prostatic cancer project (P.O.N.CA.P.) study.

Ninety-five patients with stage C (C1 + C2) or D (D1 + D2) prostatic carcinoma were treated with the depot formulation of D-TRP-6 LH-RH ("Decapeptyl") for up to 33 months. Serum testosterone (T) levels were significantly reduced to castration levels within 4 weeks and maintained persistently low. Similarly, LH levels were decreased, although they remained in the normal range. Stimulation tests with either Gn-RH or HCG in course of treatment showed the achievement of a complete pituitary desensitization and almost a complete down-regulation of testicular LH receptors. Of 88 patients evaluable for response, about one-half showed an objective response. In most cases, subjective improvement with relief of bone pain and/or urinary symptoms was obtained without major side effects. These results indicate that the depot formulation of D-TRP-6 LH-RH offers an effective therapeutic alternative for patients with advanced prostatic cancer.

Acid Phosphatase

Plasma levels of hydroxy-flutamide in patients with prostatic cancer receiving the combined hormonal therapy: an LHRH agonist and flutamide.

The present study describes a method for the measurement of the plasma levels of hydroxy-flutamide (Flu-OH), the biologically active and main circulating metabolite of flutamide. We have observed that two to four hours after oral administration of 250 mg of flutamide to healthy young men, as well as to patients with prostate cancer, the plasma concentration of Flu-OH reaches a peak at approximately 1.7 microM. The plasma concentration of Flu-OH measured at months 6, 12, and 18 of treatment shows a minimal basal level of 3.4 microM with a maximal increase at 6.8 to 8.5 microM at 2 to 4 hours. Since the serum levels of testosterone in these patients are approximately 1 nM, the levels of the active antiandrogen are at a 5000- to 10000-fold excess. However, due to the low affinity of the antiandrogen for the androgen receptor, it is extremely important to maintain this concentration of the antiandrogen in plasma constant.

Adult