[Itraconazole: a new drug-related cause of hypertension]

Virtual screening and biological evaluation to identify pharmaceuticals potentially causing hypertension and hypokalemia by inhibiting steroid 11β-hydroxylase

Several drugs were found after their market approval to unexpectedly inhibit adrenal 11β-hydroxylase (CYP11B1)-dependent cortisol synthesis. Known side-effects of CYP11B1 inhibition include hypertension and hypokalemia, due to a feedback activation of adrenal steroidogenesis, leading to supraphysiological concentrations of 11-deoxycortisol and 11-deoxycorticosterone that can activate the mineralocorticoid receptor. This results in potassium excretion and sodium and water retention, ultimately causing hypertension. With the risk known but usually not addressed in preclinical evaluation, this study aimed to identify drugs and drug candidates inhibiting CYP11B1. Two conceptually different virtual screening methods were combined, a pharmacophore based and an induced fit docking approach. Cell-free and cell-based CYP11B1 activity measurements revealed several inhibitors with IC50 values in the nanomolar range. Inhibitors include retinoic acid metabolism blocking agents (RAMBAs), azole antifungals, α2-adrenoceptor ligands, and a farnesyltransferase inhibitor. The active compounds share a nitrogen atom embedded in an aromatic ring system. Structure activity analysis identified the free electron pair of the nitrogen atom as a prerequisite for the drug-enzyme interaction, with its pKa value as an indicator of inhibitory potency. Another important parameter is drug lipophilicity, exemplified by etomidate. Changing its ethyl ester moiety to a more hydrophilic carboxylic acid group dramatically decreased the inhibitory potential, most likely due to less efficient cellular uptake. The presented work successfully combined different in silico and in vitro methods to identify several previously unknown CYP11B1 inhibitors. This workflow facilitates the identification of compounds that inhibit CYP11B1 and therefore pose a risk for inducing hypertension and hypokalemia.

Characterization of the interferences of systemic azole antifungal drugs with adrenal steroid biosynthesis using H295R cells and enzyme activity assays

Azole antifungals, designed to inhibit fungal CYP51, have a liability to inhibit human CYP enzymes. Whilst drug-metabolizing CYPs are covered in preclinical safety assessment, those metabolizing endogenous bioactive molecules are usually not. Posaconazole and itraconazole were recently found to cause pseudohyperaldosteronism with hypokalemia and hypertension by inhibiting CYP11B1-dependent adrenal cortisol biosynthesis. Because this was overlooked in preclinical safety assessment, the present study tested whether applying adrenal carcinoma H295R cells could have predicted this liability and whether other systemic triazole antifungals interfere with adrenal steroidogenesis. Forskolin-stimulated H295R cells were exposed to systemic triazole antifungals that are currently used, and key adrenal steroids were quantified by UHPLC-MS/MS. To support the findings from the H295R model, activity assays for steroidogenic enzymes were performed. The analysis of the steroid profiles and product/substrate ratios predicted the CYP11B1 and CYP11B2 inhibition by posaconazole and itraconazole. Comparison of their steroid profiles allowed distinguishing their effects and suggested inhibition of adrenal androgen synthesis by posaconazole but not itraconazole, which was confirmed by CYP17A1 17,20-lyase activity measurements. In line with clinical observations, there was no evidence from these experiments for an inhibition of either CYP11B1/2 or CYP17A1 by voriconazole, fluconazole or isavuconazole. However, itraconazole and isavuconazole exerted an overall inhibition of steroidogenesis by a mechanism warranting further investigations. In conclusion, analyses of steroid profiles from the H295R assay and product/substrate ratios provide important information on the interference of a chemical with adrenal steroidogenesis and the underlying mechanism. This approach facilitates prioritization of further investigations, including enzyme expression and activity studies.

Antifungal Therapy with Azoles Induced the Syndrome of Acquired Apparent Mineralocorticoid Excess: a Literature and Database Analysis

We aimed to estimate the risk of varied antifungal therapy with azoles causing the syndrome of acquired apparent mineralocorticoid excess (AME) in real-world practice. First, we conducted a disproportionality analysis based on data from the FDA Adverse Event Reporting System (FAERS) database to characterize the signal differences of triazoles-related AME. Second, a systematic review was conducted, and clinical features of AME cases reported in clinical practice were described. In the FAERS database, we identified 27 cases of triazoles-AME, posaconazole [ROR = 865.37; 95%CI (464.14; 1613.45)], and itraconazole [ROR = 556.21; 95% (303.05; 1020.85)] significantly increased the risk of AME events, while fluconazole, voriconazole, and isavuconazole did not affect any of the mineralocorticoid excess targets. Eighteen studies with 39 cases raised evidence of AME following posaconazole and itraconazole treatment, and another 27 cases were identified by analysis of the description of clinical features in the FAERS database. The average age of 66 patients was 55.5 years (6-87 years). AME mainly occurs in patients with posaconazole concentrations above 3 μg/mL (mean = 4.4 μg/mL, range 1.8∼9.5 μg/mL), and is less likely to occur when levels are below 2 μg/mL (6%). The median time to event onset was 11.5 weeks, and 50% of the adverse events occurred within 3 months for posaconazole. The presented study supports very recent findings that posaconazole and itraconazole, but not the other three azole antifungals investigated, are associated with AME and that the effects are dose-dependent, which allows for a dose de-escalation strategy and for substitution with fluconazole, isavuconazole, or voriconazole to resolve the adverse effects.

Pseudohyperaldosteroism during itraconazole treatment: a hitherto neglected clinically significant side effect

We describe a married couple who both presented with hypertension and hypokalaemia. Both patients were diagnosed with pseudohyperaldosteronism triggered by the widely used antifungal drug itraconazole. This effect appears to be dose-dependent, where a daily intake of 100 mg itraconazole is enough to induce pseudohyperaldosteronism. Clinicians should be aware of pseudohyperaldosteronism as a possible adverse effect of itraconazole, and we recommend monitoring potassium levels and blood pressure in all patients receiving this drug over a longer period of time. Voriconazole is probably an alternative antifungal treatment to itraconazole but also with this drug potassium levels should be monitored.

Antifungal therapy with azoles and the syndrome of acquired mineralocorticoid excess

The syndromes of mineralocorticoid excess describe a heterogeneous group of clinical manifestations leading to endocrine hypertension, typically either through direct activation of mineralocorticoid receptors or indirectly by impaired pre-receptor enzymatic regulation or through disturbed renal sodium homeostasis. The phenotypes of these disorders can be caused by inherited gene variants and somatic mutations or may be acquired upon exposures to exogenous substances. Regarding the latter, the symptoms of an acquired mineralocorticoid excess have been reported during treatment with azole antifungal drugs. The current review describes the occurrence of mineralocorticoid excess particularly during the therapy with posaconazole and itraconazole, addresses the underlying mechanisms as well as inter- and intra-individual differences, and proposes a therapeutic drug monitoring strategy for these two azole antifungals. Moreover, other therapeutically used azole antifungals and ongoing efforts to avoid adverse mineralocorticoid effects of azole compounds are shortly discussed.

The Many Faces of Itraconazole Cardiac Toxicity

Itraconazole is well known for carrying a black-box warning for new or worsening congestive heart failure. Single cases of other cardiac- and fluid-related disturbances have been reported periodically since its issuance. We describe a large cohort of patients on itraconazole experiencing a breadth of cardiac- and fluid-related toxicities, ranging from new-onset hypertension to cardiac arrest. A retrospective, single-center, large case series at a large tertiary medical center was conducted. Patients with itraconazole and cardiac toxicity—including hypertension, cardiomyopathy, reduced ejection fraction, and edema—in medical record between January 1, 1999, and May 21, 2019, were identified and assigned a Naranjo score; 31 patients were included with a Naranjo score of 5 or higher. There were slightly more male subjects than female subjects, average age was 66, and all subjects were Caucasian. Median time until presentation of adverse effects was 4 weeks (range: 0.3 to 104 weeks). Most common symptom was edema (74% of patients), followed by heart failure without and with preserved ejection fraction (19.4% and 22.6% of patients, respectively). Worsening or new hypertension was also common (25.8% of patients). Rarer were pulmonary edema, pericardial effusion, and cardiac arrest that occurred in 1 patient. In most cases, clinicians stopped itraconazole (74%) or decreased itraconazole dose (19%), resulting in improvement or resolution of symptoms. In 4 cases, the adverse effect did not resolve. Itraconazole can cause a range of possible serious cardiac and fluid-associated adverse events. Dose decrease or cessation usually resulted in symptomatic improvement or reversal.

Molecular mechanisms of posaconazole- and itraconazole-induced pseudohyperaldosteronism and assessment of other systemically used azole antifungals

Recent reports described cases of severe hypertension and hypokalemia accompanied by low renin and aldosterone levels during antifungal therapy with posaconazole and itraconazole. These conditions represent characteristics of secondary endocrine hypertension caused by mineralocorticoid excess. Different mechanisms can cause mineralocorticoid excess, including inhibition of the adrenal steroidogenic enzymes CYP17A1 and CYP11B1, inhibition of the peripheral cortisol oxidizing enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) or direct activation of the mineralocorticoid receptor (MR). Compared to previous experiments revealing a threefold more potent inhibition of 11β-HSD2 by itraconazole than with posaconazole, the current study found sevenfold stronger CYP11B1 inhibition by posaconazole over itraconazole. Both compounds most potently inhibited CYP11B2. The major pharmacologically active itraconazole metabolite hydroxyitraconazole (OHI) resembled the effects of itraconazole but was considerably less active. Molecular modeling calculations assessed the binding of posaconazole, itraconazole and OHI to 11β-HSD2 and the relevant CYP enzymes, and predicted important interactions not formed by the other systemically used azole antifungals, thus providing an initial explanation for the observed inhibitory activities. Together with available clinical observations, the presented data suggest that itraconazole primarily causes pseudohyperaldosteronism through cortisol-induced MR activation due to 11β-HSD2 inhibition, and posaconazole by CYP11B1 inhibition and accumulation of the mineralocorticoids 11-deoxycorticosterone and 11-deoxycortisol because of hypothalamus-pituitary-adrenal axis (HPA) feedback activation. Therapeutic drug monitoring and introduction of upper plasma target levels may help preventing the occurrence of drug-induced hypertension and hypokalemia. Furthermore, the systemically used azole antifungals voriconazole, isavuconazole and fluconazole did not affect any of the mineralocorticoid excess targets, offering alternative therapeutic options.

Drug-induced endocrine blood pressure elevation

Patients with uncontrolled hypertension are at risk for cardiovascular complications. The majority of them suffers from unidentified forms of hypertension and a fraction has so-called secondary hypertension with an identifiable cause. The patient's medications, its use of certain herbal supplements and over-the-counter agents represent potential causal factors for secondary hypertension that are often overlooked. The current review focuses on drugs that are likely to elevate blood pressure by affecting the human endocrine system at the level of steroid synthesis or metabolism, mineralocorticoid receptor activity, or by affecting the catecholaminergic system. Drugs with known adverse effects but where benefits outweigh their risks, drug candidates and market withdrawals are reviewed. Finally, potential therapeutic strategies are discussed.

Mineralocorticoid hypertension and hypokalaemia induced by posaconazole

We describe severe hypokalaemia and hypertension due to a mineralocorticoid effect in a patient with myelodysplastic syndrome taking posaconazole as antifungal prophylaxis. Two distinct mechanisms due to posaconazole are identified: inhibition of 11β hydroxylase leading to the accumulation of the mineralocorticoid hormone 11-deoxycorticosterone (DOC) and secondly, inhibition of 11β hydroxysteroid dehydrogenase type 2 (11βHSD2), as demonstrated by an elevated serum cortisol-to-cortisone ratio. The effects were ameliorated by spironolactone. We also suggest that posaconazole may cause cortisol insufficiency. Patients taking posaconazole should therefore be monitored for hypokalaemia, hypertension and symptoms of hypocortisolaemia, at the onset of treatment and on a monthly basis. Treatment with mineralocorticoid antagonists (spironolactone or eplerenone), supplementation of glucocorticoids (e.g. hydrocortisone) or dose reduction or cessation of posaconazole should all be considered as management strategies.

Inhibition of 11β-hydroxysteroid dehydrogenase 2 by the fungicides itraconazole and posaconazole

Impaired 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2)-dependent cortisol inactivation can lead to electrolyte dysbalance, hypertension and cardiometabolic disease. Furthermore, placental 11β-HSD2 essentially protects the fetus from high maternal glucocorticoid levels, and its impaired function has been associated with altered fetal growth and a higher risk for cardio-metabolic diseases in later life. Despite its important role, 11β-HSD2 is not included in current off-target screening approaches. To identify potential 11β-HSD inhibitors among approved drugs, a pharmacophore model was used for virtual screening, followed by biological assessment of selected hits. This led to the identification of several azole fungicides as 11β-HSD inhibitors, showing a significant structure-activity relationship between azole scaffold size, 11β-HSD enzyme selectivity and inhibitory potency. A hydrophobic linker connecting the azole ring to the other, more polar end of the molecule was observed to be favorable for 11β-HSD2 inhibition and selectivity over 11β-HSD1. The most potent 11β-HSD2 inhibition, using cell lysates expressing recombinant human 11β-HSD2, was obtained for itraconazole (IC₅₀ 139±14nM), its active metabolite hydroxyitraconazole (IC₅₀ 223±31nM) and posaconazole (IC₅₀ 460±98nM). Interestingly, experiments with mouse and rat kidney homogenates showed considerably lower inhibitory activity of these compounds towards 11β-HSD2, indicating important species-specific differences. Thus, 11β-HSD2 inhibition by these compounds is likely to be overlooked in preclinical rodent studies. Inhibition of placental 11β-HSD2 by these compounds, in addition to the known inhibition of cytochrome P450 enzymes and P-glycoprotein efflux transport, might contribute to elevated local cortisol levels, thereby affecting fetal programming.