The endocrine effects of ketoconazole

Severe Posaconazole-Induced Glucocorticoid Deficiency with Concurrent Pseudohyperaldosteronism: An Unfortunate Two-for-One Special

A 56-year-old Hispanic man with a history of disseminated coccidioidomycosis was diagnosed with persistent glucocorticoid insufficiency and pseudohyperaldosteronism secondary to posaconazole toxicity. This case was notable for unexpected laboratory findings of both pseudohyperaldosteronism and severe glucocorticoid deficiency due to posaconazole’s mechanism of action on the adrenal steroid synthesis pathway. Transitioning to fluconazole and starting hydrocortisone resolved the hypokalemia but not his glucocorticoid deficiency. This case highlights the importance of recognizing iatrogenic glucocorticoid deficiency with azole antifungal agents and potential long term sequalae.

Endocrine and metabolic manifestations of invasive fungal infections and systemic antifungal treatment

Systemic fungal infections are increasingly reported in immunocompromised patients with hematological malignancies, recipients of bone marrow and solid organ allografts, and patients with AIDS. Mycoses may infiltrate endocrine organs and adversely affect their function or produce metabolic complications, such as hypopituitarism, hyperthyroidism or hypothyroidism, pancreatitis, hypoadrenalism, hypogonadism, hypernatremia or hyponatremia, and hypercalcemia. Antifungal agents used for prophylaxis and/or treatment of mycoses also have adverse endocrine and metabolic effects, including hypoadrenalism, hypogonadism, hypoglycemia, dyslipidemia, hypernatremia, hypocalcemia, hyperphosphatemia, hyperkalemia or hypokalemia, and hypomagnesemia. Herein, we review how mycoses and conventional systemic antifungal treatment can affect the endocrine system and cause metabolic abnormalities. If clinicians are equipped with better knowledge of the endocrine and metabolic complications of fungal infections and antifungal therapy, they can more readily recognize them and favorably affect outcome.

Pharmacological management of Cushing's syndrome: an update

The treatment of choice for Cushing's syndrome remains surgical. The role for medical therapy is twofold. Firstly it is used to control hypercortisolaemia prior to surgery to optimize patient's preoperative state and secondly, it is used where surgery has failed and radiotherapy has not taken effect. The main drugs used inhibit steroidogenesis and include metyrapone, ketoconazole, and mitotane. Drugs targeting the hypothalamic-pituitary axis have been investigated but their roles in clinical practice remain limited although PPAR-gamma agonist and somatostatin analogue som-230 (pasireotide) need further investigation. The only drug acting at the periphery targeting the glucocorticoid receptor remains Mifepristone (RU486). The management of Cushing syndrome may well involve combination therapy acting at different pathways of hypercortisolaemia but monitoring of therapy will remain a challenge.

Pharmacological developments in male contraception

To date, the current methods of male contraception are limited to condoms, coitus interruptus and vasectomy, all of which are beset with difficulties. The condom is inconvenient, dulls sensation, and although somewhat effective against sexually transmitted disease, has an increased failure rate over time of usage. Coitus interruptus reduces the pleasurable aspects of intercourse and is plagued with a high failure rate. Vasectomy is virtually sterilisation. The current research into new forms of contraception is as diverse as the mechanisms controlling male fertility. The majority of effort has focused on antispermatogenic agents. Hormonal agents that suppress spermatogenesis appear nearest to final development and are primarily centred around various testosterone esters. These can be administered alone or in combination with progestogens. Another promising line of study centres on gonadotropin releasing hormone (GnRH) antagonism resulting in suppression of gonadotropins. Non-hormonal antispermatogenic agents include numerous phytochemicals, and testicular enzyme inhibitors. Post-testicular approaches to male contraception include agents that interfere with sperm metabolism, motility, maturation or transport. This review summarises recent clinical and animal studies on these compounds with emphasis on their mechanism of action, advantages and drawbacks.

Mouse hepatic metabolites of ketoconazole: isolation and structure elucidation

Oxidation, cleavage and degradation of the imidazole and piperazine rings, O-dealkylation, and aromatic hydroxylation are the reported pathways of ketoconazole (KC) metabolism. Metabolites were examined in hepatic extracts from male Swiss Webster mice treated with KC (350 mg kg-1 po x 7 days) in a 0.25% gum tragacanth suspension at 10 ml kg-1. Livers were collected 24 h after the last dose and stored at -70 degrees C. A mixture of chloroform/methanol extracts of liver homogenates were dried under vacuum and methanol extracts of the residue were chromatographed by a series of preparative and analytical HPLC techniques. Structure assignments were made by NMR and MS/MS techniques. It was demonstrated that KC was biotransformed to a number of products. Nine were isolated and seven identified as exclusive products of the biotransformation of the 1-acetylpiperazine moiety of KC. This substituent was biotransformed to the following: piperazine (de-N-acetyl ketoconazole, DAKC), N-carbamylpiperazine, N-formylpiperazine, 2,3-piperazinedione, 2-formamidoethylamine, ethylenediamine and amine. The 1H-NMR and MS data suggested that the remaining two metabolites were products resulting from the oxidation of the imidazole ring.

Ketoconazole reduces elevated serum levels of 1,25-dihydroxyvitamin D in hypercalcemic sarcoidosis

The antifungal drug ketoconazole, a cytochrome P450 inhibitor, has been shown to inhibit renal 1,25-dihydroxyvitamin D production in vitro and to lower serum 1,25-dihydroxyvitamin D levels in normal subjects and in patients with primary hyperparathyroidism. To assess the usefulness of this drug in the hypercalcemia of sarcoidosis, a condition thought to result from overproduction of 1,25-dihydroxyvitamin D by sarcoid-involved tissues, two men with sarcoidosis, hypercalcemia, and elevated serum levels of 1,25-dihydroxy-vitamin D were given ketoconazole, 600-800 mg per day, for four to six days. Serum 1,25-dihydroxyvitamin D levels were markedly reduced (by approximately 40%) in both patients during ketoconazole administration, but serum calcium was not affected. In both patients, renal function deteriorated during ketoconazole treatment. We conclude that ketoconazole administration can lower the elevated serum 1,25-dihydroxyvitamin D levels in sarcoidosis. However, deterioration of renal function during ketoconazole administration as well as failure of hypercalcemia to be affected during short-term ketoconazole treatment suggest that this drug might not be appropriate for acute treatment of hypercalcemic sarcoidosis.

Potency and specificity of CGS-16949A as an aromatase inhibitor

Inhibitors of aromatase are useful for treatment of estrogen-dependent breast cancer and as probes for study of normal physiology. Inhibitors of this enzyme with more favorable properties are necessary since the most extensively utilized inhibitor, aminoglutethimide, lacks specificity and causes frequent side effects. The present study compared the potency and specificity of a new aromatase inhibitor, CGS-16949A, with that of aminoglutethimide in a variety of in vitro enzyme preparations. CGS-16949A blocked aromatase by 50% in human breast cancer homogenates, live breast cancer cells, human placental microsomes and porcine ovarian microsomes at concentrations of 0.008 to 0.02 microM. In contrast, concentrations of 10-25 microM of aminoglutethimide were required to inhibit aromatase similarly in these tissues. For human placental microsomes, the Ki for CGS 16949A was 0.17 nM and for aminoglutethimide, 0.54 microM. Preincubation studies indicated that CGS-16949A acts by a competitive inhibitory mechanism and not by "suicide inhibitory" properties. With respect to specificity, CGS-16949A had no effect on cholesterol side-chain cleavage activity in rat testicular mitochondria. A 54% reduction in enzyme activity was observed in adrenal mitochondria but only at concentrations five orders of magnitude higher (i.e. 100 microM) than required to inhibit aromatase. In contrast, 10 microM concentrations of aminoglutethimide blocked cholesterol side-chain cleavage activity in rat testicular and adrenal mitochondria by 67 and 91%, respectively. These data suggest that CGS-16949A has favorable properties as a specific and potent aromatase inhibitor.

Aminoglutethimide and ketoconazole: historical perspectives and future prospects

Aminoglutethimide and ketoconazole, although originally developed as an anticonvulsant and antifungal agent respectively, have both been used to suppress steroid biosynthesis in patients with hormone-sensitive cancer. Aminoglutethimide inhibits several enzymes involved in the synthesis of corticosteroids as well as the aromatase enzyme which converts androgens to oestrogens. About one third of patients with breast cancer show objective improvement with aminoglutethimide, and it may also be of use in the treatment of adrenal carcinoma. However, its toxicity, and the need for concomitant cortisol replacement, severely limit its usefulness. Ketoconazole also inhibits several steroidogenic enzymes, notably C17,20-lyase, and has been used to treat carcinoma of the prostate. Again however, its toxicity and limited efficacy limit its value, although it may be useful in the treatment of certain endocrine conditions such as precocious puberty. Several aromatase inhibitors similar in structure to aminoglutethimide have been developed in an attempt to create more selective and efficient inhibitors. Some of these compounds have been tested in animals but none have as yet been subjected to clinical trials. Attempts to produce imidazole inhibitors of steroidogenesis are less advanced, although one compound (CGS 16949A) has been reported to be a more selective and potent aromatase inhibitor than aminoglutethimide. Selective and effective compounds could be of great value in the treatment of hormone-sensitive carcinoma.

Overview of medically important antifungal azole derivatives

Fungal infections are a major burden to the health and welfare of modern humans. They range from simply cosmetic, non-life-threatening skin infections to severe, systemic infections that may lead to significant debilitation or death. The selection of chemotherapeutic agents useful for the treatment of fungal infections is small. In this overview, a major chemical group with antifungal activity, the azole derivatives, is examined. Included are historical and state of the art information on the in vitro activity, experimental in vivo activity, mode of action, pharmacokinetics, clinical studies, and uses and adverse reactions of imidazoles currently marketed (clotrimazole, miconazole, econazole, ketoconazole, bifonazole, butoconazole, croconazole, fenticonazole, isoconazole, oxiconazole, sulconazole, and tioconazole) and under development (aliconazole and omoconazole), as well as triazoles currently marketed (terconazole) and under development (fluconazole, itraconazole, vibunazole, alteconazole, and ICI 195,739).

Dose and sex-dependent disposition of ketoconazole in rats

The disposition of the antifungal drug ketoconazole was studied in mature (60-day-old) male and female rats given single intravenous doses of 10, 20 or 40 mg/kg body weight. The plasma profiles of ketoconazole were characterized by an initial rapid decline, followed by an apparent zero-order decline and a subsequent first-order elimination phase. In male animals the zero-order phase was less pronounced, resulting in a 3-5 times higher overall rate of elimination. A consequence of the dose-dependent disposition was that a 4-fold increase in dose resulted in a 9- and 17-fold increase in the area under the plasma concentration-time curve (AUC) of females and males, respectively. Terminal half-lives were independent of dose in both sexes. The disproportionate increase in AUC with dose, together with the observation that no intact ketoconazole was excreted in urine and only very small amounts in bile (less than 1% of given dose), suggest that the dose-dependent disposition is caused by saturation of metabolizing enzymes. These enzymes are most likely under the influence of androgens, since the capacity of males to eliminate ketoconazole was reduced by castration and in females this capacity was increased by testosterone treatment.