The Effect of Danazol on Anterior Pituitary Function**Supported by Grant 20305 from the FRSM and CGER Foundation for Cancer Research

Danazol

A comprehensive profile of danazol describing the nomenclatures, formulae, elemental composition, appearance, uses and applications is presented. The profile contains the method which was utilized for the preparation of the drug substance and its respective scheme is outlined. The physical characteristics of the drug including the solubility, X-ray powder diffraction pattern, differential scanning calorimetry, thermal behavior and spectroscopic studies are described. The methods which were used for the analysis of the drug substance in bulk drug and/or in pharmaceutical formulations including the compendial, spectrophotometric, electrochemical and the chromatographic methods are reported. The stability, toxicity, pharmacokinetics, bioavailability, drug evaluation and monitoring, comparisons, pharmacology, in addition to several compiled reviews on the drug substance which were involved. Finally, two hundred and seventy-nine references are listed at the end of this profile.

Danazol inhibits aromatase activity of endometriosis-derived stromal cells by a competitive mechanism

OBJECTIVE

To evaluate the inhibitory effect of danazol on estrogen (E) production in endometriosis.

DESIGN

Prospective randomized study.

SETTING

Academic research unit of the department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Thirteen patients with endometriosis.

INTERVENTION(S)

Danazol was added to the culture of endometriosis-derived stromal cells or suspensions of microsomes prepared from chocolate cysts.

MAIN OUTCOME MEASURE(S)

The aromatase activities as well as mRNA and protein levels of aromatase in endometriosis-derived stromal cells or microsomes of endometriosis were examined.

RESULT(S)

Danazol treatment with a concentration greater than 10(-6) M significantly suppressed aromatase activity of endometriosis-derived stromal cells under basal and prostaglandin E(2) (PGE(2))-stimulated conditions. Danazol (10(-5) M) did not affect mRNA and protein levels of aromatase. Danazol competitively inhibited aromatase activity (by 1.7 x 10(-6) M of calculated Ki and 2.9 x 10(-5) M of Ki') of endometriosis microsomes.

CONCLUSION(S)

Danazol competitively inhibited aromatase activity in endometriosis-derived stromal cells without affecting either the mRNA or protein levels of aromatase. These results indicate the efficacy of local application of danazol to endometriotic lesions.

Local application of danazol-loaded hyaluronic acid hydrogel to endometriosis in a rat model

OBJECTIVE

To evaluate the efficacy of a drug delivery system composed of danazol-loaded hyaluronic acid for local application to endometriosis.

DESIGN

Prospective, randomized study.

SETTING

Academic research unit of the department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Adult female Sprague-Dawley rats.

INTERVENTION(S)

Danazol-loaded hyaluronic acid hydrogel (DZ-HA gel) was injected into the rat endometriosis model.

MAIN OUTCOME MEASURE(S)

Size and histological changes in experimental endometriosis, the concentration of danazol in the cyst wall and plasma, and estrous cycles were examined.

RESULT(S)

Histologically, DZ-HA gel-treated cysts displayed marked atrophy of the endometrial epithelium. Increased numbers of apoptotic cells and decreased numbers of proliferative cells were noted with 10 mg/mL DZ-HA gel. Size of treated cysts decreased to approximately 60% at 9 weeks after injection. The estrous cycles were not disturbed during DZ-HA gel treatment.

CONCLUSION(S)

Local injection of DZ-HA gel achieved endometrial atrophy of an experimental model of endometriosis without disturbing the sexual cycle. These results suggest that local application of DZ using this drug delivery system may prove useful for treating endometriosis.

Inhibition of the first ovulation and ovarian prostaglandin F2 alpha metabolism by danazol in rats

The present study was conducted to investigate the mode of action of danazol by monitoring the first ovulation, serum luteinizing hormone (LH) levels and ovarian prostaglandin (PG) F2 alpha metabolism in pregnant mare serum gonadotropin (PMSG)-primed immature female rats. When danazol (750 mg/kg) was given p.o. once a day for 5 days (day 24-28), the occurrence of the first ovulation, the increase in capacity to form 13,14-dihydro-PGF2 alpha and PGF2 alpha levels induced by PMSG (5 IU) injected on day 26 were clearly inhibited on day 29. Danazol also markedly suppressed the LH surge occurring on day 28. Although the danazol-induced blockage of ovulation was restored by injection of human chorionic gonadotropin, the number of oocytes was significantly decreased as compared with that of controls. The present data indicate that the inhibitory actions of danazol on ovulation and ovarian PGF2 alpha metabolism may occur via some direct effects on the ovary in addition to the suppression of gonadotropin release from the pituitary gland.

Thermoregulatory and endocrine effects of a low dose of danazol in postmenopausal women: interaction with the effect of naloxone

Before and on the 30th day of danazol administration (200 mg/day), in six postmenopausal women the activity of endogenous opioid peptides has been indirectly evaluated by the effect on LH secretion and body temperature (measured as rectal temperature) exerted by the infusion of the opioid antagonist naloxone (1.6 mg/h x 4 h preceded by 1.6 mg iv bolus). Before and during danazol administration a GnRH test (100 mcg iv bolus) was also performed to evaluate possible variations in pituitary responsiveness to GnRH. Danazol significantly reduced mean plasma levels of LH and FSH (p less than 0.01), and their response to GnRH stimulus (p less than 0.05). Either before or during danazol administration mean plasma LH and FSH levels did not vary during the infusion of naloxone, while body temperature significantly decreased (p less than 0.01). The decrease in body temperature was significantly greater (p less than 0.05) during danazol than before treatment. The present data suggest that in postmenopausal women a low dose of danazol exerts an antigonadotropic effect mainly reducing the pituitary responsiveness to GnRH. The enhanced hypothermic response to naloxone observed during danazol administration also seems to suggest that in postmenopausal women a low dose of danazol enhances the thermoregulatory role of endogenous opioid peptides.

Prolactin and its response to the luteinizing hormone-releasing hormone thyrotropin-releasing hormone test in patients with endometriosis before, during, and after treatment with danazol

Basal levels of prolactin (PRL) were studied in 16 normal women and in 60 women with endometriosis, 37 of whom were infertile. In addition, the authors studied the response to an intravenous (IV) injection of luteinizing hormone-releasing hormone (LH-RH) (100 micrograms) plus thyrotropin-releasing hormone (TRH) (300 micrograms) in the 16 normal women and in 18 endometriosis patients, examining the basal PRL and thyrotropin, and at 15, 30, 45, 60, and 120 minutes after the IV bolus. After laparoscopy and/or conservative surgery, the patients were treated with danazol for 6 months and a second laparoscopy was performed. The LH-RH/TRH test was carried out in the third month of danazol treatment in 6 endometriosis patients and before the second laparoscopy in 11 patients. The results show that there was both an increase in the mean basal levels of PRL and in the percentage of cases of moderate hyperprolactinemia in endometriosis patients. There also was a greater rise in PRL with the LH-RH/TRH test in moderate and severe endometriosis. The PRL response was significantly greater in endometriosis than in normal women, and was not related to TSH response. Danazol treatment reduced significantly the PRL response. The PRL response before treatment was significantly higher in patients who after treatment showed persistent endometriosis at the second laparoscopy. This could suggest a lower effectiveness of danazol in patients with endometriosis and a PRL hyper-response to LH-RH/TRH.

The inhibitory effects of danazol, danazol metabolites, gestrinone, and testosterone on the growth of human endometrial cells in vitro

Danazol and gestrinone are effective drugs in the treatment of endometriosis. Their mechanism of action remains uncertain, but may be related to their androgenic activity. The authors examined the effect of danazol on human endometrial cells cultured in vitro, its two major metabolites, ethisterone and 2 hydroxymethyl ethisterone, gestrinone, and testosterone (T) at 1X and 10X expected plasma concentrations. Danazol and T suppressed growth by 20.8 and 25.0% (P less than 0.01), respectively, at the lower dose, and by 26.9 and 35.5% (P less than 0.01), respectively, at the 10-fold higher dose. No significant suppression of growth occurred with gestrinone, ethisterone, or 2 hydroxymethyl ethisterone. The results provide further evidence that danazol and T (but not gestrinone) may act by a direct effect on endometrial tissue.

A clinical trial using danazol for the treatment of premenstrual tension

Forty women with premenstrual tension received either placebo, 100, 200 or 400 mg danazol daily for 3 months in a pilot study arranged as a double-blind trial. Thirteen patients withdrew by the third month usually because they complained of no improvement. They had significantly higher pretrial symptom scores than those who continued. In patients treated with danazol, symptom scores for breast pain during the second and third months and for irritability, anxiety and lethargy during the third month were significantly (P less than 0.05) lower than scores in those given placebo. Most symptoms improved on placebo in the first month but by the third month only three remained improved. In contrast eight symptoms were improved on 200 mg danazol by the third month. By the end of the trial more than 75% of patients who were still taking danazol were essentially free of breast pain, lethargy, anxiety and increased appetite, but results for other common symptoms were no better than with placebo.

Endocrine consequences of danazol treatment in menorrhagia

In order to study the endocrine side-effects of danazol, 15 patients with severe, benign menorrhagias, were individually treated with this drug to stop bleeding. LH, FSH, testosterone, free testosterone, DES-S, androstenedione, prolactin, estradiol and cortisol serum concentrations were measured before and after the 3 month treatment period. Danazol was found to be effective in reducing the amount of bleeding in patients with benign, severe menorrhagias; however, the weight gain of patients was significant during the 3 month period. LH and estradiol concentrations decreased; testosterone, free testosterone and dehydroepiandrosterone sulfate increased; prolactin, FSH, androstenedione and cortisol serum concentrations did not change, and SHBG disappeared from the serum, during the treatment period. We are of the opinion that danazol is an effective drug in menorrhagias with side-effects. In our view the hyperandrogenicity is the most important side-effect of this substance, which might be the result of some metabolites, but which might be the effect of a peripheral action of the drug as well.

Direct biphasic effects of danazol on gonadotropin-dependent differentiation of cultured rat granulosa cells

The direct effects of danazol on granulosa cell differentiation were studied in vitro over a broad concentration range with a primary culture of rat granulosa cells. Whereas treatment with low-dose (defined herein as less than 10(-6) M) danazol by itself was without significant effect on basal steroid secretion, combined treatment with low-dose danazol (10(-7) M) and a minimally effective dose of follicle-stimulating hormone (FSH, 20 ng/ml) resulted in a substantial augmentation of the FSH effect. Although independent of the FSH dose employed, the effect of danazol proved dose- and time-dependent, with an apparent median effective dose of 3.6 +/- 0.3 X 10(-8) M. In contrast, high-dose danazol (defined herein as greater than 10(-6) M) produced dose-dependent inhibition of FSH (250 ng/ml)-supported steroid secretion. Taken together, our findings indicate that the effects of danazol on granulosa cell differentiation may be biphasic in nature, displaying a stimulatory low-dose component, followed by inhibition at higher dose levels.

Danazol inhibits steroidogenesis by the human ovary in vivo

Gonadotropins, estradiol (E2), and the steroid precursors of ovarian estrogen secretion were examined in women on danazol to clarify actions of the medication on hypothalamic-pituitary-ovarian function. Follicle-stimulating hormone was not altered acutely after a single maximal dose or chronically during therapy, whereas a slight but significant increase in luteinizing hormone was noted during the 6 months of treatment. During danazol treatment, there was a blunted response of E2 to injections of human menopausal gonadotropins. The progestin and androgen precursors of E2 were reduced, with the exception of 17-hydroxypregnenolone, which was significantly increased. This 17-hydroxylase enzyme block persisted in spite of dexamethasone suppression of adrenal function. Therefore, the reduced ovarian secretion of E2 in women receiving danazol is due in part to reductions of ovarian precursor steroids for E2 synthesis, consequent to a direct ovarian action of the medication.

Cytoplasmic and nuclear estrogen binding capacity in the rat uterus during treatment with danazol and testosterone

Danazol, testosterone and dihydrotestosterone (DHT) were tested as competitors for estrogen receptors on immature rat uterus cytosol. No competitive binding could be demonstrated for any of these steroids. After that, prepubertal Wistar rats were exposed to danazol, testosterone or propylene glycol (control) for 3 days or 17 days. After the appropriate exposure to medication, the animals were killed. Both danazol and testosterone appeared to be uterotropic after 3 days of treatment, although the increase in the uterine weight was significant only in the danazol-treated group (p less than 0.05). This effect was lost after 17 days of treatment. Estradiol receptor binding assays were done on the cytosolic and nuclear fractions of the homogenized uterine tissue of each group. The estrogen binding capacity of cytosols was increased in both the danazol (p less than 0.05) and the testosterone (p less than 0.01) groups after 3 days of treatment. A parallel increase was found in the nuclear fraction of both groups. After 17 days of treatment, the comparison between the 3 groups showed no differences in the cytosolic or nuclear estrogen binding capacity. The information provided by this study suggests that some effects of danazol may be due to an androgenic action and that may be associated to increases in the free fraction of testosterone.

Inhibition of gonadotropin-releasing hormone receptors in rat anterior pituitary monolayer cell cultures by danazol

To study possible cellular antigonadotropic effects of danazol, monolayer cultures of anterior pituitary cells from immature female rats were treated with danazol. Measurements of luteinizing hormone release in response to 10(-8) mol/L gonadotropin-releasing hormone challenge and iodine 125-labeled gonadotropin-releasing hormone binding activity were done after exposure to increasing concentrations of danazol and for increasing lengths of time. It was found that luteinizing hormone secreted by pituitary cells in response to gonadotropin-releasing hormone was inhibited after danazol treatment in a dose- and time-dependent manner when compared to controls. Also, a 45% decrease in gonadotropin-releasing hormone receptor binding capacity was observed in pituitary cells cultured in the presence of increasing concentrations of danazol in the range of 10(-8) to 10(-4) mol/L when compared to controls. Furthermore, exposure to danazol for 25 to 96 hours caused a marked decrease in gonadotropin-releasing hormone binding activity (p less than 0.005). Under these experimental conditions danazol treatment decreased the pituitary receptors for gonadotropin-releasing hormone in a dose- and time-dependent manner. Scatchard analysis of saturation curves for the binding of gonadotropin-releasing hormone to cellular gonadotropin-releasing hormone receptors indicated that the observed decrease in gonadotropin-releasing hormone binding in the danazol-treated group was due to a change in the number of gonadotropin-releasing hormone binding sites rather than a change in the affinity. It is therefore concluded that the antigonadotropic activity of danazol appears to be related to a decrease in gonadotropin-releasing hormone receptors in the pituitary.

Danazol treatment of advanced prostate cancer: clinical and hormonal effects

Danazol was administered to 19 patients with advanced prostate cancer. These patients were treated for periods ranging from 3 days to 18 weeks. There were no objective remissions, but three patients (15.8%) had objectively stable disease (N.P.C.P. criteria) with complete pain control for periods ranging 15-18 weeks. Seven patients experienced tumor flare reactions, one requiring withdrawal of treatment and one resulting in rapid clinical deterioration and death. Four other patients died within 3 weeks and, although they were already in the terminal phase of disease when treatment commenced, it is possible that the deaths were treatment related. This study indicates that danazol has only limited activity in the treatment of advanced prostate cancer and is associated with a high incidence of tumor flare reactions with the risk of rapid clinical deterioration.

Changes in the biochemical composition of semen following danazol plus testosterone enanthate administration to the langur monkey

Changes in the biochemical composition of semen, which reflect the accessory sex organ functions, following danazol (100 mg/day; orally) plus testosterone enanthate (50 mg/month; i.m.) administration have been investigated in langur monkey. The levels of acid phosphatase, lactic dehydrogenase and glycerylphosphorylcholine in the semen decreased significantly; whereas fructose, citric acid, magnesium and semen volume did not show any significant changes. A gradual decrease in the motility and count of spermatozoa was observed. At 60 days of treatment all animals became azoospermic. No drug related hematological changes were observed. The combination therapy impaired the epididymal and prostatic functions along with suppression of spermatogenesis.

Endocrine effects of danazol in the treatment of endometriosis

The effects of danazol therapy on circulating gonadotrophins, oestradiol and sex hormone-binding globulin (SHBG) binding capacity have been studied in eight patients with endometriosis. There was a significant rise in luteinizing hormone (LH) in the first week of treatment with a fall in oestradiol levels. There was a marked fall in SHBG in the first week which continued up to 4 weeks. It is concluded that danazol is not 'anti-gonadotrophic' as frequently claimed and that its therapeutic actions, side effects and the endocrine changes could be explained by an effect on SHBG production. The rationale of its use in other conditions requires reconsideration.

The interaction of human endometrial and myometrial steroid receptors with danazol

The affinity of danazol for oestrogen, androgen and progesterone receptors in human endometrium and myometrium was determined, to study the mechanism of action of this drug in the treatment of endometriosis. The ability of danazol to combine with each of the three types of receptor was similar in both endometrium and myometrium. The capacity of danazol to compete with oestradiol-17 beta for the oestrogen receptor was very low (1.72 +/- 0.48 X 10(-3%) cross reaction, mean +/- SEM) and danazol, at the maximum concentration used, was unable to saturate the receptor; but danazol's ability to compete with progesterone for its receptor was considerably higher (8.41 +/- 1.65% using progesterone, 1.95 +/- 0.41% using R5020) and was saturable. Danazol was also able to displace dihydrotestosterone from the cytosol androgen receptor (6.29 +/- 1.82% cross reaction). The association constant of oestradiol for the endometrial and myometrial oestrogen receptors was 2.19 X 10(9)M-1 and 7.45 X 10(9)M-1 respectively, while that of progesterone and dihydrotestosterone for their receptors was similar in endometrium and myometrium (mean 0.25 +/- 0.06 X 10(9) M-1 and 3.62 +/- 1.67 X 10(9) M-1 respectively). Using R5020, the association constant for the myometrial progesterone receptor was 2.50 +/- 0.73 X 10(9) M-1. We conclude that, in view of the high circulating levels of danazol present in patients being treated for endometriosis, it is possible that danazol may bind to, and partly saturate, endometrial and myometrial oestrogen, progesterone and androgen receptors during treatment. An explanation may thus be provided for some of the diverse actions of this drug.

Peripheral androgen levels in danazol-treated premenopausal women

Eighteen normally menstruating women with endometriosis were treated with 600 mg of danazol daily for 6 months. Blood samples were taken before and after 2, 4, 8, 12, and 16 weeks of treatment and were analyzed for plasma dehydroepiandrosterone sulfate (DHEA-S), dehydroepiandrosterone (DHEA), and testosterone (T) and for serum alanine aminotransferase (ALAT), albumin, creatinine, potassium, and sodium. The basal values of all parameters studied were well within normal reference limits. DHEA-S was significantly increased at 2, 4, and 8 weeks, and DHEA significantly decreased at 8 and 12 weeks of treatment. The ratio between DHEA and DHEA-S was significantly decreased at weeks 4, 8, 12, and 16. T was significantly decreased during the whole period of observation. ALAT was significantly increased at weeks 4, 8, 12, and 16. A slight but significant increase was observed for creatinine and potassium, while no changes were observed for albumin and sodium. Of the two major androgen sources, the adrenal cortex appears to be relatively unaffected; whereas the ovary may be affected to a minor degree. Therefore, it seems likely that the changes observed in DHEA and DHEA-S may be due to minor alterations in renal and hepatic turnover rather than an effect on adrenal steroidogenesis.

Effects of danazol on pulsatile gonadotropin patterns and on serum estradiol levels in normally cycling women

The effect of danazol on pulsatile luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol (E2) secretion was examined in eight premenopausal women by serial blood sampling on day 10 of the control and first treatment cycles and during 2 subsequent months of treatment. The mean frequency of LH pulses decreased, while the mean pulse amplitude and increment increased (P less than 0.05). The mean LH concentrations were significantly suppressed in four of eight subjects. The mean frequency of E2 pulses, mean increment, and mean integrated area were decreased (P less than 0.05). The mean integrated FSH area did not change significantly during treatment, and we were not able to demonstrate unequivocal FSH pulses. We conclude that danazol in premenopausal women (1) lowers serum E2 concentrations by decreasing the frequency and increment of E2 pulses, (2) prevents compensatory gonadotropin rise, and (3) lowers the frequency but increases the amplitude and increment of LH pulses. The latter change reflects probably divergent effects of the drug on the pituitary and hypothalamus and results in an inconsistent lowering of basal LH levels.

Influence of danazol treatment during the luteal phase on pituitary and ovarian function during the subsequent menstrual cycle

Eight subjects with normal menstrual cycles were treated with danazol (800 mg daily) during one luteal phase to assess the effect on follicular development in the subsequent cycle. Plasma levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and progesterone were measured daily throughout both cycles. Following danazol there was a consistent and significant delay to the preovulatory estradiol (P less than 0.05) and LH (P less than 0.02) peaks and a significant suppression of the early follicular phase FSH (P less than 0.05) and preovulatory estradiol peak plasma levels (P less than 0.05). All other parameters of the post-danazol cycle were indistinguishable from normal. However, there was a small suppression of midluteal phase FSH during danazol treatment, compared with the posttreatment cycle, which was significant for three subjects. It is suggested that the small effect of luteal phase danazol on subsequent follicle development may occur at an intraovarian level through an effect on receptors or enzymes as well as through the small degree of suppression of midluteal phase and early follicular phase FSH.

Changes of prolactin secretion following long-term danazol application

Patients (n = 10) with endometriosis or fibrocystic mammary disease were treated with an oral dose of 4 x 200 mg danazol for 6 months. Prolactin and gonadotropin secretion was evaluated before, and in some of them during 1, 3, and 6 months of therapy, as well as 4 weeks after discontinuation of the steroid. Prolactin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and progesterone were measured before a bolus of 10 mg metoclopramide and 25 micrograms LH-releasing hormone (LH-RH) had been given. The serum concentrations of prolactin and LH were estimated 25 minutes and those of FSH 45 minutes thereafter. Basal and stimulated serum prolactin levels, measured during the luteal phase of the control cycle preceding danazol application, decreased continuously, reaching serum concentrations seen during the early follicular phase of the cycle. This was paralleled by a decrease of estradiol and a lack of progesterone secretion. While basal and LH-RH-stimulated LH was practically unchanged, basal and stimulated FSH showed a significant increase. Within 4 weeks of discontinuation of the drug all hormonal parameters were similar to pretreatment values. The data presented may explain the beneficial effect of the drug on fibrocystic mammary disease, i.e., by the decrease of serum and pituitary prolactin. The selective increase of FSH secretion is unclear but may reflect the lack of negative feedback mechanisms of follicular inhibin.

Danazol: endocrine pharmacology and therapeutic applications

The options for the medical management of endometriosis have been expanded by the introduction of the synthetic steroid, danazol. The results of large clinical studies suggest that danazol treatment produces significant improvement in the symptoms, signs, and laparoscopic findings of endometriosis. The original studies of the pharmacology of danazol concluded that danazol was a strong antigonadotrophin with mild androgenic effects and no other hormonal properties. Recent studies which emphasize the molecular pharmacology of danazol suggest that this steroid has direct effects on hypothalamic-pituitary function, multiple classes of steroid receptors, gonadal steroidogenesis, and endogenous steroid metabolism. These studies demonstrate that: (1) danazol prevents the midcycle surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH); (2) danazol does not significantly suppress basal LH or FSH in gonadally intact human beings; (3) in castrated animals danazol can prevent the compensatory increase in LH and FSH; (4) danazol binds to androgen, progesterone, and glucocorticoid receptors; (5) danazol does not bind to estrogen receptors; (6) danazol binds to sex hormone-binding globulin and corticosteroid-binding globulin; (7) danazol inhibits multiple enzymes of steroidogenesis; (8) danazol increases the metabolic clearance rate of progesterone; and (9) metabolites of danazol are hormonally active. Given the complex pharmacology of danazol it is inappropriate to continue to refer to danazol as a "selective antigonadotrophin."U

Hormone binding globulin levels in patients with hereditary angiooedema during treatment with Danazol

Five patients with hereditary angiooedema were treated with Danazol for periods up to 10 months. This therapy resulted in normalization of serum levels of the inhibitor of the first complement component and disappearance of clinical disease symptoms in all patients. Although a variety of hormones were measured, only those of the pituitary-gonadal axis altered during treatment: a moderate decrease in leuteinizing hormone levels and a sharp fall of testosterone in adult men were observed. In all patients, however, both sex hormone binding globulin and thyroxine binding globulin concentrations were considerably suppressed during Danazol therapy. However, levels of corticosterone binding globulin and thyroxine binding globulin concentrations were considerably suppressed during Danazol therapy. However, levels of corticosterone binding globulin remained unchanged. The fraction of endogenous testosterone not bound to sex hormone binding globulin invariably increased. The possible relevance of these findings to the understanding of the mode of action of Danazol both in these patients and in general, are discussed.

Danazol suppression of luteinizing hormone secretion: a role for danazol-androgen receptor interaction within the brain-pituitary complex

We investigated the relationship between intracellular androgen and estrogen receptors within the brain-pituitary complex and danazol suppression of luteinizing hormone secretion in castrated rats. Danazol did not influence 3H-estradiol-estrogen receptor interactions within the brain and pituitary but did suppress 3H-dihydrotestosterone-androgen receptor interactions within this neuroendocrine complex. To study the significance of these danazol-androgen receptor interactions, the drug was administered to androgen receptor-deficient pseudohermaphrodite or flutamide-treated male rats. In both instances, danazol suppression of luteinizing hormone release was markedly attenuated or absent. These findings point to danazol-androgen receptor interactions within the brain-pituitary complex as a key step in this drug's antigonadotropic actions. Whether the active drug form is danazol itself or a metabolite is subject to further study.

Dosage aspects of danazol therapy in endometriosis: short-term and long-term effectiveness

The use of danazol (Danocrine) appears to be the most effective medical form of therapy for endometriosis. A double-blind study on 32 patients with laparoscopically proved pelvic endometriosis was designed to evaluate the immediate short-term and long-term effectiveness of daily dosages of danazol (100, 200, 400, and 600 mg) on the amelioration of the disease, with the use of posttreatment surgical findings and symptomatic changes. The American Fertility Society classification based on a point system was used. The clinical and surgical improvement rates varied from 75% to 85% and 50% to 70%, respectively. Ovarian endometriomas of even 1 cm in size generally do not respond to danazol. The pregnancy rate was 45%. We have demonstrated that lower than maximum doses of danazol produce similar beneficial effects in the treatment. With the low dosages, we did not achieve freedom from side-effects. The average symptomatic recurrence rate was 36%, with a mean duration of 19 months of follow-up, and was dose dependent.

Review: The mechanism of action of danazol, a novel steroid derivative

Danazol is being increasingly used for the treatment of a wide range of disorders, many of which appear to bear little relation to the condition for which the drug was originally marketed--endometriosis. It has been claimed that this drug acts by means of its antigonadotrophic effects on the pituitary; however, a review of the literature reveals that its efficacy in suppressing normal endometrial growth and in causing atrophy of deposits of endometrium cannot be explained solely on this basis. Recent information indicates that, besides acting at the pituitary level, a major mechanism of action may be by a direct inhibitory effect on target tissue. It is sugggested that such a mechanism would more readily account for the diverse effects of this drug in the treatment of many disorders, all of which appear to be associated with an imbalanced sensitivity of target organs to steroid hormones. A greater understanding of its mechanism of action could lead to an even wider application of this novel drug.

Effect of danazol on serum gonadotrophins and steroid hormone concentrations in women with menorrhagia

In 13 ovulatory women with objective evidence of menorrhagia (menstrual blood loss greater than 80 ml), danazol 400 mg given daily for 12 weeks suppressed ovulation as shown by absence of gonadotrophin peaks, low serum progesterone levels and flat basal body temperature recordings. Serum concentrations of luteinising hormone and follicle stimulating hormone were within the range found during the normal menstrual cycle but oestradiol concentrations tended to fall, reaching levels less than 100 pmol/l in some patients. Danazol treatment had no effect on levels of androstenedione or dehydroepiandrosterone and its sulphate. The presence or absence of cyclical bleeding on treatment, and the measured blood loss was unrelated to circulating oestradiol levels.

Effect of danazol on estradiol-17beta and progesterone secretion by porcine ovarian cells in vitro

The effect of danazol on progesterone (P4) and estradiol-17 beta (E2) secretion by cultured porcine granulosa cells was studied. Danazol markedly inhibited both basal and luteinizing hormone (LH)-stimulated P4 secretion by both granulosa and luteal cells in a dose-dependent manner during 24 hour culture periods. E2 secretion by granulosa cells was low (less than 3 ng/mg of protein) when cultured in the absence of an exogenous aromatizable substrate but was markedly increased when testosterone (T) was added to the media. Danazol inhibited E2 secretion by granulosa cells only when cultured in the presence of testosterone. E2 secretion by luteal cells was low even in the presence of testosterone and was not affected by danazol. These findings support the hypothesis that danazol can directly inhibit ovarian steroidogenesis independently of its inhibitory action on gonadotropin secretion.

Danazol binding to rat androgen, glucocorticoid, progesterone, and estrogen receptors: correlation with biologic activity

Danazol was found to possess androgenic and glucocorticoid activity in rat bioassays. In contrast, danazol displayed no significant estrogenic activity. In support of these findings, danazol bound to the 8 S androgen receptor of rat prostate cytosol and to the glucocorticoid receptor of rat liver cytosol, but danazol did not bind well to the estrogen receptor of the rat uterus. Finally, danazol bound to the progesterone receptor of the rat uterus, but controversy continues as the whether danazol possesses progestational, antiprogestational, or no progestational effects.

The galactorrhoea-endometriosis syndrome

A new syndrome consisting of galactorrhoea and endometriosis is described. Nine patients with endometriosis, eight of whom had galactorrhoea either at diagnosis or after treatment with danazol are reported. Prolactin concentrations were normal in seven patients. Galactorrhoea in a woman with regular menstrual periods should suggest a possible diagnosis of underlying endometriosis, especially if there is a history of dysmenorrhoea.