Sedative-hypnotic Binding to 11β-hydroxylase

Pharmacological management of severe Cushing's syndrome: the role of etomidate

Cushing's syndrome (CS) is an endocrine disease characterized by excessive adrenocortical steroid production. One of the mainstay pharmacological treatments for CS are steroidogenesis enzyme inhibitors, including the antifungal agent ketoconazole along with metyrapone, mitotane, and aminoglutethimide. Recently, osilodrostat was added to this drug class and approved by the US Food and Drug Administration (FDA) for the treatment of Cushing's Disease. Steroidogenesis enzyme inhibitors inhibit various enzymes along the cortisol biosynthetic pathway and may be used preoperatively to lower cortisol levels and reduce surgical risk associated with tumor resection or postoperatively when surgery and/or radiation therapies are not curative. Because their selectivities for steroidogenic enzymes vary, they may even be administered in combination to achieve relatively rapid control of severe hypercortisolemia. Unfortunately, all currently available inhibitors are accompanied by serious adverse side effects that limit dosing and often result in treatment failures. Although more commonly known as a general anesthetic induction agent, etomidate is another member of the steroidogenesis enzyme inhibitor drug class. It suppresses cortisol production primarily by inhibiting 11β-hydroxylase and is the only inhibitor that may be given parenterally. However, the sedative-hypnotic actions of etomidate limit its use as an acute management option for CS. Thus, some have recommended that it be used only in intensive care settings. In this review, we discuss the initial development of etomidate as an anesthetic agent, its subsequent development as a treatment for CS, and the recent advances in dosing and drug development that dissociate sedative-hypnotic and adrenostatic drug actions to facilitate CS treatment in non-critical care settings.

High affinity interaction of Solanum tuberosum and Brassica juncea residue smoke water compounds with proteins involved in coronavirus infection

The world is in an immediate need of treatment for coronavirus disease (COVID-19). Chronic exposure of hydroxychloroquine in the treatment of COVID-19 may have multiple adverse effects on human physiology, such as cardiac arrhythmias. Natural compounds need to be evaluated as treatment and preventive agents in coronavirus infection. A total of 30 compounds of Solanum tuberosum and Brassica juncea residue smoke water were selected for the virtual screening against SARS-CoV-1, SARS-CoV-2 and cellular proteins involved in the mechanism of infection. Docking analysis identified lead molecules with favorable binding energy, number of poses and hydrogen bond interactions, which indicates the effective modulation of ACE2 and TMPRSS2 receptors. Results indicated (a) curcumenol, (b) N-desmethylselegiline, (c) phentermine and (d) sphingolipid derivatives as a selective and potent candidates in comparison to hydroxychloroquine for COVID-19 treatment. Our in silico findings, therefore, warrant further in vitro validations of the selected compounds for the discovery of novel preventive and therapeutic drug against SARS-CoV-2 infection.

New insights for screening etomidate analogues in the human H295R cell model

Etomidate is a sedative-hypnotic with excellent pharmacological effects, including rapid onset and hemodynamic stability. However, etomidate causes adrenocortical toxicity via binding to 11β-hydroxylase. Therefore, developing an approach to screen new etomidate analogues without endocrine-disrupting effects is urgently warranted. In this study, we employed the adrenocortical tumour cell line, NCI-H295R, as an in vitro system for etomidate analogues screening and detected the hormone levels in these cells using a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. After obtaining the concentration-response curves of hormone release, the "Adrenocortical Inhibitory Index" was used to evaluate the adrenocortical inhibitory potency of each compound. In summary, we demonstrate the benefits of our methods for screening of etomidate analogues that lack adrenocortical suppression, especially when this in vitro system is combined with in vivo testing.

Soft drugs in anesthesia: remifentanil as prototype to modern anesthetic drug development

PURPOSE OF REVIEW

The unique demands of modern anesthesia practice require that medications be effective, well tolerated, and efficient. These attributes are increasingly achieved with the soft drug approach, wherein novel active compounds are specifically designed to be susceptible to rapid biotransformation to inactive metabolites. The present review summarizes the historical background and recent trends in soft drug development in anesthesiology.

RECENT FINDINGS

Soft drug development programs for propranadid, etomidate, and benzodiazepine analogues have been undertaken in recent years. Although all three drugs advanced into human trials, neuro-excitatory adverse effects hampered the propranadid and etomidate analogue projects. Remimazolam, the soft benzodiazepine analogue, is at an advanced stage of development, having already received regulatory approval or review in several countries.

SUMMARY

With succinylcholine as the historical forerunner and remifentanil as the modern prototype, the soft drug paradigm continues to hold promise for the future of anesthesia drug development.

Endocrine disruptors of inhibiting testicular 3β-hydroxysteroid dehydrogenase

Testicular 3β-hydroxysteroid dehydrogenase (HSD3B) is a steroidogenic enzyme, catalyzing the conversion of 3β-hydroxysteroids into 3-keto-steroids. Two distinct isoforms in the human are cloned, HSD3B1 and HSD3B2, and HSD3B2 is located in the testis. HSD3B2 is a two-substrate enzyme, which binds to cofactor NAD⁺ and a 3β-steroid. Many endocrine disruptors, including industrial compounds (phthalates, bisphenols, and perfluoroalkyl substances), insecticides and biocides (organochlorine insecticides and organotins), food additives (butylated hydroxyanisole, resveratrol, gossypol, flavones, and isoflavones), and drugs (etomidate, troglitazone, medroxyprogesterone acetate, and ketoconazole) inhibit testicular HSD3B, possibly interfering with androgen synthesis. In this review, we discuss the distinct testicular isoform of HSD3B, its gene, chemistry, subcellular location, and the endocrine disruptors that directly inhibit testicular HSD3B and their inhibitory modes.

Anesthetic Drug Discovery and Development: A Case Study of Novel Etomidate Analogs

All currently available general anesthetic agents possess potentially lethal side effects requiring their administration by highly trained clinicians. Among these agents is etomidate, a highly potent imidazole-based intravenous sedative-hypnotic that deleteriously suppresses the synthesis of adrenocortical steroids in a manner that is both potent and persistent. We developed two distinct strategies to design etomidate analogs that retain etomidate's potent hypnotic activity, but produce less adrenocortical suppression than etomidate. One strategy seeks to reduce binding to 11β-hydroxylase, a critical enzyme in the steroid biosynthetic pathway, which is potently inhibited by etomidate. The other strategy seeks to reduce the duration of adrenocortical suppression after etomidate administration by modifying the drug's structure to render it susceptible to rapid metabolism by esterases. In this chapter, we describe the methods used to evaluate the hypnotic and adrenocortical inhibitory potencies of two lead compounds designed using the aforementioned strategies. Our purpose is to provide a case study for the development of novel analogs of existing drugs with reduced side effects.

Dimethoxy-etomidate: A Nonhypnotic Etomidate Analog that Potently Inhibits Steroidogenesis

Cushing's syndrome is characterized by the overproduction of adrenocortical steroids. Steroidogenesis inhibitors are mainstays of medical therapy for Cushing's syndrome; unfortunately, adverse side effects and treatment failures are common with currently available drugs. The general anesthetic induction agent etomidate is among the most potent inhibitors of adrenocortical steroidogenesis. However, its use as a treatment of Cushing's syndrome is complicated by its sedative-hypnotic activity and ability to produce myoclonus, central nervous system actions thought to be mediated by the GABA_A receptor. Here, we describe the pharmacology of the novel etomidate analog (R)-ethyl 1-(1-(3,5-dimethoxyphenyl)ethyl)-1H-imidazole-5-carboxylate (dimethoxy-etomidate). In contrast to etomidate, dimethoxy-etomidate minimally enhanced GABA-evoked GABA_A receptor-mediated currents even at a near-saturating aqueous concentration. In Sprague-Dawley rats, dimethoxy-etomidate's potency for producing loss of righting reflexes-an animal model of sedation/hypnosis-was 2 orders of magnitude lower than that of etomidate, and it did not produce myoclonus. However, similar to etomidate, dimethoxy-etomidate potently suppressed adrenocortical steroid synthesis primarily by inhibiting 11β-hydroxylase. [³H]etomidate binding to rat adrenocortical membranes was inhibited by dimethoxy-etomidate in a biphasic manner with IC₅₀ values of 8.2 and 3970 nM, whereas that by etomidate was monophasic with an IC₅₀ of 22 nM. Our results demonstrate that, similar to etomidate, dimethoxy-etomidate potently and dose-dependently suppresses adrenocortical steroid synthesis by inhibiting 11β-hydroxylase. However, it is essentially devoid of etomidate's GABA_A receptor positive modulatory and sedative-hypnotic activities and produces no myoclonus, providing proof of concept for the design of etomidate analogs without important central nervous system actions for the pharmacologic treatment of Cushing's syndrome.