Pituitary gonadotropin inhibitory activity of danazol

Microbial transformation of danazol with Cunninghamella blakesleeana and anti-cancer activity of danazol and its transformed products

Biotransformation of danazol (1) (17β-hydroxy-17α-pregna-2,4-dien-20-yno-[2,3-d]-isoxazole) with Cunninghamella blakesleeana yielded three new metabolites 2-4 and a known metabolite 5. These metabolites were identified as 14β,17β-dihydroxy-2-(hydroxymethyl)-17α-pregn-4-en-20-yn-3-one (2), 1α,17β-dihydroxy-17α-pregna-2,4-dien-20-yno-[2,3-d]-isoxazole (3), 6β,17β-dihydroxy-17α-pregna-2,4-dien-20-yno-[2,3-d]-isoxazole (4), and 17β-hydroxy-2-(hydroxymethyl)-17α-pregn-1,4-dien-20-yn-3-one (5). Danazol (1) and its derivatives were evaluated against cervical cancer cell line (HeLa). Compound 1 showed a potent cytotoxicity with IC50=0.283±0.013 μM, as compared to doxorubicin (IC50=0.506±0.015 μM), where compound 3 was also found to be significantly active with IC50=13.427±0.819 μM.

A benefit-risk assessment of medical treatment for uterine leiomyomas

The growth of a uterine leiomyoma growth stops and regresses after the menopause suggesting that leiomyoma growth is dependent on ovarian steroids. Therefore, estrogen has received much attention as the major factor responsible for the development of uterine leiomyomas, but progesterone also plays an important role in development of this disease. Cytogenetic analyses of resected samples has revealed that about 40 to 50% of leiomyomas show karyotypically detectable chromosomal abnormalities. Gonadotrophin releasing hormone (GnRH) agonists exert their action through the suppression of endogenous gonadotrophins and gonadal steroid secretion. Significant reductions of uterine/leiomyoma volume under GnRH agonist therapy has been reported in several studies. However, the leiomyoma generally returns to its pretreatment volume within a few months after discontinuation of the GnRH agonist. To minimise the adverse effects of hypoestrogenism during GnRH agonist treatment, add back therapy can be used (estrogen-progestin, progestin alone and recently tibolone). Antiprogestins have a potential clinical utility in uterine leiomyomas. Mifepristone is a synthetic steroid with both antiprogesterone and antiglucocorticoid activities, that may have an inhibitory effect on growth of leiomyoma. Danazol is an isoxazole of 17beta-ethinyl testosterone, a synthetic steroid, which has a suppressive effect on sex hormone binding globulin concentrations, resulting in efficacy in the short-term treatment of uterine leiomyomas. Gestrinone is a tri-enic steroid with antiestrogen and antiprogesterone properties and has been shown to reduce uterine volume and stop bleeding. Growth factors play a relevant role on the pathophysiology of uterine leiomyoma and probably the inhibition of the action of growth factors on the myometrium will be the basis for future therapy. A number of agents are under investigation for treating uterine leiomyoma. Agents developed from increasing genetic knowledge of this condition could represent, in the next few years, new trends in the medical treatment of uterine leiomyomas.

Pain recurrence: a quality of life issue in endometriosis

Studies reveal endometriosis to be present in 38-51% of women undergoing laparoscopy for chronic pelvic pain. Symptoms attributable to endometriosis include dysmenorrhea, dyspareunia, generalized pelvic pain, dyschezia, and radiation of pain to the back or leg. Psychological factors may also contribute to a more intense pain experience. Medical therapy provides symptom relief in 72-93% of patients, although recurrence is common following treatment discontinuation. Surgical therapy has had varying results for long-term pain relief; adequacy of the initial surgical treatment appears to be a critical factor. Important adjunctive measures include presacral neurectomy and excisional techniques to remove deep, fibrotic, retroperitoneal lesions. The quality of life of women with endometriosis will improve with greater focus on achieving the long-term relief of pelvic pain. Limitation of pain recurrence would benefit the patient greatly, by providing symptom relief and preventing the cycle of its probably adverse effects on physical activity, work productivity, sexual fulfilment, and mood.

Effects of danazol on endometrial DNA synthesis in rats

The suppressive effects of Danazol, an isoxazol derivative of the synthetic steroid 17 alpha-ethinyltestosterone, on endometrial DNA synthesis were investigated in rats by immunohistochemistry with bromodeoxyuridine (BrdU) and DNA-synthesizing enzyme assays. Rats treated with Danazol for 14 days at 17-19 weeks of age showed a decrease of plasma gonadotropins associated with ovarian hypofunction, persistent diestrus, and a smaller number of corpora lutea in ovary, resulting in no BrdU-immunoreactive (S-phase) cells in endometrial epithelium and lower activity of thymidine kinase in the uterus compared with control.

Effects of danazol on DNA synthesis in rat prostate

Effects of danazol, an isoxazol derivative of the synthetic steroid 17 alpha-ethinyltestosterone, on activities of thymidylate synthetase and thymidine kinase, which are the DNA-synthesizing enzymes included in de novo and salvage pathways of pyrimidine metabolism, respectively, were investigated in rat prostate. Danazol markedly reduced plasma levels of luteinizing hormone and testosterone, and organ weight, both enzyme activities and bromodeoxyuridine-immunoreactive cells which were regarded as the S-phase cells in prostate. These results indicate that danazol shows a property as a potent antigonadotropin.

The effect of danazol on tumour control and weight loss in patients on tamoxifen therapy for advanced breast cancer: a randomised double-blind placebo controlled trial

To assess the effect of danazol in advanced breast cancer 183 patients were randomised to receive either tamoxifen plus danazol or tamoxifen plus placebo. Patients underwent systemic work-up pretreatment then every 12 weeks or sooner if they clinically progressed. There were no differences in objective response rates with tamoxifen plus danazol vs. tamoxifen plus placebo (27% vs. 24%), time to progression (median 6.4 vs. 6.2 months) or survival (median 22.6 vs. 23.5 months) when the two arms were compared (all P > 0.5). The addition of danazol to tamoxifen had no effect on time to progression when adjusted for significant prognostic factors in a multivariate analysis. However, it was found incidentally that weight was stable on tamoxifen plus danazol (average gain 0.6 kg, S.E. 0.6 kg) compared with a significant loss on tamoxifen plus placebo (average loss 2.0 kg, S.E. 0.6 kg, P = 0.003). The average weight was maintained on tamoxifen plus danazol even in patients who did not respond to treatment.

Progesterone receptor induction by danazol in cultured cancer cells and the rat uterus

We have previously reported that clinical trials relating to the use of danazol in the management of benign breast disease show a positive correlation between favourable clinical response and an induction of progesterone receptors in the affected tissue which is maintained for a period of at least 6 months subsequent to the cessation of treatment. Further studies designed at elucidating more clearly the actions of danazol at the cellular and molecular levels have confirmed that progesterone receptors are down-regulated by short-term progestin action at the level of the mRNA transcript, but that danazol is subsequently able to produce an enhanced cellular response, inducing progesterone receptors in the presence of oestrogenic agents. Uteri from danazol-treated rats showed a doubling of progesterone receptor concentrations compared with the control uteri. In the mammary cancer cell line T-47D, cells treated with danazol had increased progesterone receptor concentrations of 558.4 +/- 32.0 compared with 152.6 +/- 7.0 fmol/mg protein in the control cells. In both cases, these inductions were observed following a period of progesterone receptor suppression. Short-term molecular studies on T-47D cells indicated that progesterone and danazol initially inhibit mRNA transcription, but that 24 h after treatment an induction is observed. This is especially marked in the danazol-treated cells.

Inhibitory and stimulatory actions of danazol in rat ovarian and uterine tissues

We examined whether danazol has a direct action on ovarian steroid secretion and/or uterine prostaglandin (PG) F2 alpha catabolic activity in immature rats in which the first ovulation was induced and in adult ovariectomized rats. The preovulatory surge of estradiol and progesterone was markedly suppressed together with that of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by danazol administration under conditions that blocked the first ovulation. Uterine weight and PGF2 alpha catabolic activity enhanced by endogenous estrogen were greatly decreased by danazol treatment at a dose that did not block the first ovulation in immature rats. When danazol (30 mg) was given s.c. once daily for 2 days to ovariectomized rats, the uterine weight and PGF2 alpha catabolic activity per uterus were clearly increased, and the compensatory increase in FSH levels as a result of castration was not influenced, although the compensatory increase in LH levels was inhibited. These results demonstrate that danazol has a direct action on the ovary and uterus, and give further support to the view put forward in our previous paper that these actions of danazol may contribute to its therapeutic effects.

Suppression of the development of uterine adenomyosis by danazol treatment in mice

Inhibitory effects of danazol, an isoxazol derivative of synthetic steroid 17 alpha-ethinyl-testosterone, on the development of uterine adenomyosis, a pathological disorder of endometrial tissue defined as the presence of endometrial glands and stroma in the myometrium, were investigated in mice of SHN strain. Mice treated with 0.5 microgram danazol for 5 weeks during 4-9 weeks of age and killed at 21 weeks of age showed significantly lower incidence of the spontaneous development of adenomyosis than the age-matched intact control mice. The inhibitory effects of danazol were also evident in mice bearing pituitary isografts which were effective in inducing an early and a high incidence of adenomyosis. Furthermore, the treatment with danazol resulted in the decrease of serum levels of luteinizing hormone (LH) and prolactin (PRL) associated with hypofunction of ovaries and persistent diestrus. These results support the usefulness of danazol for the clinical treatment of gynecological disorders except for hypofunction of ovaries.

Effects of an androgenic derivative on pre-established mammary tumours chemically induced in the rat

The effects were studied of an androgenic derivative--danazol--administered at doses of 10-12 mg kg-1 day-1 during 97 days to rats with dimethylbenz[a] anthracene-induced mammary tumours. Our main observations were as follows. (a) Danazol did not influence ovarian function at the end of the assay. (b) The treatment with danazol reduced the incidence (P less than 0.05), number of tumours (P less than 0.05) and volume of malignant mammary tumours; on the other hand, the values of these parameters for benign tumours and those of doubtful expression were similar in both experimental groups. (c) Such differential action of Danazol seems to be due to the different incidence and/or content of receptors of both types of tumours. (d) The latter results lead to a hypothesis for the mechanism of action of danazol based on its behaviour at different levels.

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.

Studies on the mechanism of action of danazol and gestrinone (R2323) in the rat: evidence for a masked estrogen component

The effects of androgen and estrogen receptor antagonists on the action of danazol and gestrinone (R2323) were investigated. The tropic effect of danazol and gestrinone on sex accessory tissues of castrated, immature male rats was inhibited by the antiandrogen flutamide, whereas the uterotropic action of these steroids in immature female and adult ovariectomized rats was not inhibited by flutamide. In contrast, the uterotropic effect of danazol was reduced by the antiestrogen, LY156758. The estrogen-sensitive endpoints, vaginal keratinization and uterine progesterone receptor concentration, were enhanced by treatment with a combination of flutamide and either danazol or gestrinone. These data indicate that danazol and gestrinone have estrogenic activity that is masked by the androgenic component of these drugs.

Metabolism of steroid-modifying anticancer agents

The application of steroid-modifying drugs as a strategy for the treatment of hormone-dependent cancers has gained increasing popularity during the past decade. However, it is important to point out and emphasize that very few of the agents were originally designed for their current application. Most were designed for other purposes, predominantly fertility control (e.g. LHRH agonists and the antiestrogens). Nevertheless, now it is possible to integrate their actions to design rational therapies. There are many reasons for the current interest in antisteroidal drugs. The initial euphoria over the potential ability of combination chemotherapy to cure breast and prostatic carcinoma has proved to be premature. Combination chemotherapy has many severe side-effects which limits patient acceptability, especially if the patient realizes that the likelihood of a cure is remote. In the main, antisteroidal therapies do not have many side-effects and those that do, e.g. aminoglutethimide, are the focus of increased efforts in drug design to produce increased drug specificity. Finally, there is a growing realization that hormone-dependent cancer control with a nontoxic, antisteroidal therapy may be the most acceptable approach currently available for early disease management. Chemotherapy would then be reserved as the final option for treatment. The description of drug metabolism has been central to the development of synthetic LHRH analogs and an understanding of the mode of action of nonsteroidal antiestrogens and antiandrogens. The discovery of steroid synthetic pathways has been essential for the development of the aromatase inhibitors. This whole area of endeavor has now become a major focus of attention for the medicinal chemist. A new generation of agents is entering clinical evaluation which will provide a wealth of valuable information about the successful (or unsuccessful?) methods to control hormone-dependent disease. Since the success or failure of a drug can often depend upon formulation, pharmacokinetics, bioavailability or metabolism, it is our hope that this overview might help solve some of the future problems.

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 and fetal masculinization: a warning

Masculinization of a female fetus occurred during a pregnancy in which the mother received danazol for infertility due to endometriosis. The biochemical theories and the necessary treatment are outlined. Conception may occur before or during a course of danazol, and patients should be made aware of the need for concomitant contraception.

Danazol binding to steroid receptors in human uterine endometrium

To understand the mechanism of action of danazol, the binding of danazol to multiple classes of intracellular steroid binding proteins was studied in the human uterine endometrium. Danazol bound to endometrial receptors for estrogen, progesterone, and androgen and seemed to bind to endometrial intracellular corticosteroid-binding globulin and sex-hormone-binding globulin. Danazol occupies almost all binding sites of steroids in the steroid target cells in spite of the presence of endogenous steroids. It is speculated that the binding behavior of danazol may be related to its therapeutic effect on endometriosis.

Reversible inhibition of spermatogenesis by danazol with combination of testosterone enanthate in rabbit

Danazol (15 mg/kg b.w./day; oral) with combination of testosterone enanthate (5 mg/kg b.w./15 days; S.C.) was tested in male rabbits for reversible suppression of spermatogenesis. Semen analyses for efficacy and reversibility were performed biweekly. The regimen resulted in complete azoospermia or severe oligozoospermia in all the animals within 75 days of treatment accompanied with decreased motility, vitality and increased sperm abnormalities. Semen volume and pH did not alter significantly. Libido was unaffected. All seminal characteristics were within normal range after 115 days of recovery. In conclusion, the drug combination in given dose regimen resulted in reversible inhibition of spermatogenesis in rabbits.

The effect of danazol on gonadotropin secretion during the follicular phase of the menstrual cycle

The effects of danazol on pulsatile luteinizing hormone (LH) release, basal LH and follicle-stimulating hormone serum levels, gonadotropin release induced by estradiol (E2) and gonadotropin-releasing hormone were examined in five eugonadal women. Danazol administration resulted in a significant suppression of follicle-stimulating hormone serum levels. LH concentrations and LH pulse frequency appeared to be reduced, but these changes did not reach statistical significance. The pituitary response to exogenous gonadotropin-releasing hormone was not altered. The stimulatory effect of E2 on LH secretion was completely abolished in one subject, severely diminished in three subjects, and unchanged in one subject. In addition, the time course of this response was altered. Serum prolactin concentrations were lowered, whereas basal E2 and progesterone levels did not seem to be affected.

Effect of danazol on gonadal steroidogenesis in patients with a complete form of testicular feminization

The clinical applicability of danazol has been postulated to depend upon its antigonadotropic and androgenic properties. However, the true mechanism of action of danazol has not been fully elucidated, and experimental evidence indicates that the major pharmacologic action of this drug may be related to the direct inhibition of multiple enzymes of gonadal steroidogenesis. In the present study, the hypothesis that danazol directly inhibits gonadal steroidogenesis was tested during the course of endocrine studies on three sisters with a complete form of testicular feminization. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), and testosterone (T) levels were determined following short-term administration of varying doses of danazol. In these patients, the absence of androgen receptors and the expected inability of danazol to serve as a metabolic precursor of estrogens would minimize possible antigonadotropic effects of this drug and allow the evaluation of its direct action on the secretion of steroids by the gonads in vivo. During the experiments, there was a highly significant and dose-related suppression of serum T levels in all patients. E2 levels decreased slightly. Both LH and FSH levels showed no consistent decline and remained within the range of normal. In one patient, LH and FSH levels declined significantly during treatment, but in the other two patients serum concentrations of LH remained stable or even increased while T levels fell. In spite of the fall in steroid levels, a compensatory increase in gonadotropins did not always occur. In conclusion, danazol effectively suppresses peripheral T levels in patients with a complete form of testicular feminization. Such suppression is dose related and can occur in the absence of a decline in LH serum concentrations, possibly as a result of a direct action on gonadal steroidogenesis.l

Actions of danazol in vivo on cytochrome P-450 and steroidogenic enzymes in rat testis and liver microsomal preparations

The mechanism of action of danazol has not been established and the drug may act at multiple loci. Effects suggesting inhibition of pituitary gonadotropin release have been described while some in vitro studies have demonstrated competitive inhibition of steroidogenic enzymes. In addition, destruction of cytochrome P-450 by the acetylenic moiety of danazol is a possible mechanism. Following 14 days of danazol treatment (10 mg/kg/day), the specific content of rat testis microsomal cytochrome P-450 and the serum testosterone were decreased, in spite of no significant change in serum luteinizing hormone. Furthermore, simultaneous administration of human chorionic gonadotropin with danazol still resulted in a decrease in cytochrome. The activities of two testicular microsomal steroid-converting enzymes (17 alpha-hydroxylase and 17,20-lyase) were not altered when based on cytochrome P-450 content but were markedly depressed when based on microsomal protein. In liver, danazol showed a similar but less marked dimunition of the cytochrome. Surprisingly, steroid 17 alpha-hydroxylase activity in liver was significantly increased while other cytochrome P-450 dependent enzyme activities were not altered.

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

Estrogenic and antiestrogenic effects of danazol administration in studies of estradiol receptor binding

In order to study possible cellular estrogenic and/or antiestrogenic effects of danazol, immature female rats were treated with danazol (10 mg/kg/day) or propylene glycol (control) for 4 days (short-term study) and 14 days (long-term study). Estradiol receptor-binding assays were done on the cytosol fraction of the homogenized uterine tissue of each group. AT saturation levels of substrate, short-term danazol treatment was uterotropic and induced an increase in estradiol receptor concentration and binding (p less than 0.02). Long-term treatment, however, caused a marked decrease in estradiol receptor capacity (p less than 0.001). This disparity of the effect of danazol on estradiol receptors suggests a dose- or duration-dependent mechanism of action in the target tissue that may account for some of the clinical effects seen in patients receiving this drug.

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.

Evidence that danazol inhibits gonadotropin-induced ovarian steroidogenesis at a point distal to gonadotropin-receptor interaction and adenosine 3',5' cyclic monophosphate formation

The action of danazol on 125I-human chorionic gonadotropin (hCG) binding, gonadotropin-stimulated adenosine 3',5' cyclic monophosphate (cAMP) accumulation and progesterone production has been investigated in luteinized rat ovaries. Preincubation of luteal cells for short periods of time with increasing concentrations of danazol caused a significant inhibition of gonadotropin-stimulated steroidogenesis. The inhibitory effect of danazol was both concentration and time dependent. Danazol also reduced progesterone production in response to cholera enterotoxin and 8 bromo-adenosine-cAMP, but it had no effect on hCG, luteinizing hormone, and cholera enterotoxin stimulated cAMP formation. Similarly danazol did not affect 125I-hCG binding as assessed by the equilibrium dissociation constant (Kd) and number of hormone-binding sites on the luteal cell surface. These results suggest that in intact luteal cells danazol inhibits steroidogenesis at a point distal to hormone-receptor interaction and cAMP formation.

Danazol treatment of endometriosis: long-term follow-up

Forty-nine women diagnosed as having pelvic endometriosis were treated with 800 mg of danazol/day for a mean duration of 6 months. The average length of the follow-up period was 78 months. Side effects were minimal, and regular ovulatory menses returned within 25 to 90 days (average 42 days). Forty-two (85.7% of these women had associated infertility. Recurrence of symptoms was reported in 33% but in no patient were the symptoms worse than before entering the study. Of 30 patients desirous of pregnancy, 20 were potentially fertile; of these, 10 conceived within 6 months of discontinuing therapy, for a conception rate of 50%. Nine of the remaining ten patients required additional therapeutic procedures (surgery and/or danazol), and four of these conceived within 12 months. These results compare favorably with those of other investigations, since most of our patients were referred to us after being subjected to a variety of regimens, both hormonal and surgical.

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.

Effects of Danazol on pituitary gonadotrophins in post-menopausal women

Multiple sampling was carried out in 4 postmenopausal women for measurement of LH and FSH before and at the end of a 1-week treatment period with Danazol (400 mg daily). A small but significant depression of FSH was found in 3 of 4 subjects, while a significant depression of LH was only seen in 1 subject. In view of the very modest gonadotrophin suppression demonstrated in these women it is possible that Danazol also exerts its profound and sometimes rapid effects through inhibition of positive oestrogen feedback and by direct actions on the ovaries and endometrium.

Radioimmunoassay for danazol in human and monkey plasma

A sensitive method is described for the radioimmunoassay of danazol in monkey and human plasma. Antiserum was developed in rabbits, and a second antibody was used to separate bound from free danazol. The radioimmunoassay was specific for danazol, and the limit of detection ranged from 1.4 to 2.8 ng/ml. Exogeneous danazol could be quantitated accurately in both monkey and human plasma. The radioimmunoassay results agreed with values obtained by inverse isotope dilution after intravenous administration of 14C-danazol to monkeys. The assay was used successfully to measure danazol in plasma from human volunteers receiving 200 mg of danazol.

Fertility in the rhesus monkey following long-term inhibition of ovarian function with danazol

Danazol was previously reported to be an oral contraceptive in the rhesus monkey at doses of 200 and 400 mg/monkey/day for 90 days. The drug is now shown to be an effective long-term inhibitor of ovarian function in the monkey. In the final 3 months of a 27-month period of treatment at a dose of 400 mg/monkey/day, the drug continued to be an effective oral contraceptive. During the 27-month treatment period, three of seven monkeys were amenorrheic and the remaining had only 16 of the 109 expected menstrual cycles. Following the discontinuation of medication, all seven monkeys conceived within 2 to 6 weeks. One monkey aborted early in pregnancy and the remaining six delivered normal, healthy infants at term. Therefore, following the discontinuation of long-term treatment with danazol in the monkey, there was rapid and complete return of normal ovarian function.

A radioimmunoassay for danazol (17alpha-pregna-2,4-dien-20-yno[2,3-d]isoxazol-17-ol)

A method is described for the radioimmunoassay of circulating levels of the pituitary inhibiting agent, danazol. An antigen for danazol was prepared by reacting a 17-carboxy-methyloxime derivative of danazol with bovine serum albumin. By immunizing rabbits with this antigen, antiserum was generated which shows excellent specificity for danazol relative to its known metabolites as well as to many natural steroids. A radioimmunoassay was developed, without using separation or extraction techniques, involving competition for the antiserum between danazol in plasma and 14C-danazol. This assay has been successfully used to measure danazol in a series of normal human subjects receiving the drug at either 100 or 200 mg b.i.d. for 2 weeks. A significant relationship was seen between dosage of danazol and plasma concentrations.

Danazol therapy in hormone-sensitive mammary carcinoma

The effect of Danazol, a synthetic gonadotropin inhibitor, on two groups of Sprague-Dawley rats with dimethylbenze (a) anthracine (DMBA) induced mammary carcinoma was studied. Twenty-four (83%) of 29 control animals developed mammary tumors. Forty-four rats in one treatment group received Danazol after tumor reached 0.5 cm in diameter. Twenty-nine (66%) demonstrated tumor regression (p less than 0.005) and in 16 (36%) tumor disappeared (p less than 0.005). In a second treatment group (given Danazol daily after administration of DMBA), only seven of 50 rats (14%) developed palpable mammary carcinoma (p less than 0.0005). Danazol therapy resulted in regression of established mammary carcinoma in rats, and produced a striking inhibition of carcinogenesis in those animals treated from the time DMBA was administered. Danazol is clinically safe; studies using it in the treatment of breast cancer in women who are candidates for hormonal ablative therapy seem warranted.

Progestational activity of danazol in the human female subject

A progestational action of Danazol has not been reported in the human subject. Danazol administration for 1 month suppressed serum FSH and estradiol values, and the midcycle LH surge; ovulation promptly resumed after treatment. Administration to patients with polycystic ovarian disease resulted in increased LH values, elevated basal temperature, secretory findings in the endometrial biopsy, and menses. Ovarian biopsy did not document corpus luteum formation, and plasma progesterone did not rise. Administration of Danazol to an ovariectomized patients pretreated with estrogen resulted in an atypical endometrial secretory change. Clinical responses to Danazol may in part be explained by a progestational-like effect of the drug.

Danazol: an antigonadotropic agent in the treatment of pelvic endometriosis

Danazol, an antigonadotropic agent, was administered in a dosage of 800 mg. daily for six months to 32 patients with pelvic endometriosis. Twenty-eight patients (87.5 per cent) were found to have a marked improvement of both clinical and subjective symptoms of endometriosis. Furthermore, Danazol was found to be effective in three patients with chronic cystic mastitis and one patient with fibrocystic disease. There was no change in uterine size in two patients with uterine adenomyosis and one patient with uterine myomas during the treatment period. Danazol was ineffective in relieving the symptoms of the menopausal syndrome in one patient. The main side effects of Danazol treatment were weight gain and water retention which were maximal at four months of treatment and then decreased. Other side effects such as acne, oiliness of skin, and voice change were rare in this series. Danazol therapy was found to be very effective in this study for the treatment of pelvic endometriosis, and the drug was well tolerated by the patients.

Adrenal function during chronic danazol administration

Ten healthy female volunteers received Danazol, 400 mg twice daily for 90 days. Adrenal function testing then showed a normal capacity of the gland to respond to stimulation with synthetic adrenocorticotrophic hormone, and a lack of suppression of central areas controlling adrenal function by a normal response to the metyrapone challenge.