Variability in hydrocortisone plasma and saliva pharmacokinetics following intravenous and oral administration to patients with adrenal insufficiency

Salivary Cortisol Measurement Contamination After Oral Hydrocortisone: A Randomized Crossover Trial

The study aimed to evaluate salivary cortisol (SC) contamination and determine the associated factors in secondary adrenal insufficiency (SAI) patients treated with hydrocortisone (Hc). A randomized crossover trial involved SAI patients. SC was measured before the morning Hc dose, then at one, two, and four hours after. The procedure was performed twice on two days of a week: one day while taking Hc in tablet form (tablet set) and one day while taking Hc in capsule form (capsule set). Area under the curve (AUC) of SC levels over time was calculated in each participant for the two sets. SC contamination was defined as AUCtablet above the 95th percentile of AUCcapsule. Thirty-four patients (24 females and 10 males) with a median age of 48 years were enrolled. Post-Hc dose SC levels were higher in tablet than in capsule set, particularly at one hour. Prevalence and extent of SC contamination were estimated to 32% and 88%, respectively. In capsule set, SC measured two hours after Hc intake showed the strongest correlation with AUC (r=0.88, p<0.001). In multivariate analysis, serum potassium≥3.9 mEq/l was the only predictor for SC contamination [multi-adjusted OR (95% CI): 7.1 (1.4-36.1); p=0.018]. SC measured during the two hours after Hc intake is inaccurate for glucocorticoid replacement therapy assessment in SAI patients treated with Hc in tablet form.

Can we Predict Drug Excretion into Saliva? A Systematic Review and Analysis of Physicochemical Properties

BACKGROUND AND OBJECTIVES

Saliva is a patient-friendly matrix for therapeutic drug monitoring (TDM) but is infrequently used in routine care. This is due to the uncertainty of saliva-based TDM results to inform dosing. This study aimed to retrieve data on saliva-plasma concentration and subsequently determine the physicochemical properties that influence the excretion of drugs into saliva to increase the foundational knowledge underpinning saliva-based TDM.

METHODS

Medline, Web of Science and Embase (1974-2023) were searched for human clinical studies, which determined drug pharmacokinetics in both saliva and plasma. Studies with at least ten subjects and five paired saliva-plasma concentrations per subject were included. For each study, the ratio of the area under the concentration-time curve between saliva and plasma was determined to assess excretion into saliva. Physicochemical properties of each drug (e.g. pKa, lipophilicity, molecular weight, polar surface area, rotatable bonds and fraction of drug unbound to plasma proteins) were obtained from PubChem and Drugbank. Drugs were categorised by their ionisability, after which saliva-to-plasma ratios were predicted with adjustment for protein binding and physiological pH via the Henderson-Hasselbalch equation. Spearman correlation analyses were performed for each drug category to identify factors predicting saliva excretion (α = 5%). Study quality was assessed by the risk of bias in non-randomised studies of interventions tool.

RESULTS

Overall, 42 studies including 40 drugs (anti-psychotics, anti-microbials, immunosuppressants, anti-thrombotic, anti-cancer and cardiac drugs) were included. The median saliva-to-plasma ratios were similar for drugs in the amphoteric (0.59), basic (0.43) and acidic (0.41) groups and lowest for drugs in the neutral group (0.21). Higher excretion of acidic drugs (n = 5) into saliva was associated with lower ionisation and protein binding (correlation between predicted versus observed saliva-to-plasma ratios: R2 = 0.85, p = 0.02). For basic drugs (n = 21), pKa predicted saliva excretion (Spearman correlation coefficient: R = 0.53, p = 0.02). For amphoteric drugs (n = 10), hydrogen bond donor (R = - 0.76, p = 0.01) and polar surface area (R = - 0.69, p = 0.02) were predictors. For neutral drugs (n = 10), protein binding (R = 0.84, p = 0.004), lipophilicity (R = - 0.65, p = 0.04) and hydrogen bond donor count (R = - 0.68, p = 0.03) were predictors. Drugs considered potentially suitable for saliva-based TDM are phenytoin, tacrolimus, voriconazole and lamotrigine. The studies had a low-to-moderate risk of bias.

CONCLUSIONS

Many commonly used drugs are excreted into saliva, which can be partly predicted by a drug's ionisation state, protein binding, lipophilicity, hydrogen bond donor count and polar surface area. The contribution of drug transporters and physiological factors to the excretion needs to be evaluated. Continued research on drugs potentially suitable for saliva-based TDM will aid in adopting this person-centred TDM approach to improve patient outcomes.

Interpretation of Steroid Biomarkers in 21-Hydroxylase Deficiency and Their Use in Disease Management

The most common form of congenital adrenal hyperplasia is 21-hydroxylase deficiency (21OHD), which in the classic (severe) form occurs in roughly 1:16 000 newborns worldwide. Lifelong treatment consists of replacing cortisol and aldosterone deficiencies, and supraphysiological dosing schedules are typically employed to simultaneously attenuate production of adrenal-derived androgens. Glucocorticoid titration in 21OHD is challenging as it must balance the consequences of androgen excess vs those from chronic high glucocorticoid exposure, which are further complicated by interindividual variability in cortisol kinetics and glucocorticoid sensitivity. Clinical assessment and biochemical parameters are both used to guide therapy, but the specific purpose and goals of each biomarker vary with age and clinical context. Here we review the approach to medication titration for children and adults with classic 21OHD, with an emphasis on how to interpret adrenal biomarker values in guiding this process. In parallel, we illustrate how an understanding of the pathophysiologic and pharmacologic principles can be used to avoid and to correct complications of this disease and consequences of its management using existing treatment options.

Clinical and Technical Aspects in Free Cortisol Measurement

Accurate measurement of cortisol is critical in adrenal insufficiency as it reduces the risk associated with misdiagnosis and supports the optimization of stress dose. Comprehensive assays have been developed to determine the levels of bioactive free cortisol and their clinical and analytical efficacies have been extensively discussed because the level of total cortisol is affected by changes in the structure or circulating levels of corticoid-binding globulin and albumin, which are the main reservoirs of cortisol in the human body. Antibody-based immunoassays are routinely used in clinical laboratories; however, the lack of molecular specificity in cortisol assessment limits their applicability to characterize adrenocortical function. Improved specificity and sensitivity can be achieved by mass spectrometry coupled with chromatographic separation methods, which is a cutting-edge technology to measure individual as well as a panel of steroids in a single analytical run. The purpose of this review is to introduce recent advances in free cortisol measurement from the perspectives of clinical specimens and issues associated with prospective analytical technologies.

Impact of short-term hydrocortisone intake on pituitary and adrenal function in healthy young male subjects

PURPOSE

The aim of this study was to evaluate the impact of short-term therapeutic hydrocortisone intake on pituitary and adrenal function in healthy young male subjects.

METHODS

Ten physically active men received 50 mg/per day of hydrocortisone at 8:00 a.m. for 5 days. Cortisol, DHEA, and ACTH concentrations in plasma, and cortisol and DHEA concentrations in saliva were determined the week before, just before (8:00 a.m.) and 2 h after (10:00 a.m.) drug ingestion on days 1, 3, and 5 of treatment and day 1 post treatment.

RESULTS

Hydrocortisone intake induced a significant increase in both plasma cortisol (×3) and saliva cortisol (×10) concentrations 2 h after administration. Plasma and saliva DHEA concentrations were significantly decreased, as were plasma ACTH concentrations, 2 h after administration, with an increase in the cortisol/DHEA and cortisol/ACTH ratios. However, no change in cortisol, DHEA, ACTH, cortisol/DHEA, or cortisol/ACTH was observed 24 h after the last intake during treatment or post treatment, except for a downward trend in saliva DHEA at days 3 and 5. The correlations between plasma and saliva cortisol, DHEA, and cortisol/DHEA were significant: respectively, r = 0.80, r = 0.80, and r = 0.88.

CONCLUSIONS

Once-daily oral therapeutic administration of hydrocortisone for 5 days altered adrenal DHEA secretion by inhibiting pituitary ACTH, but this effect seemed transient without significant impairment of basal adrenal or pituitary function 24 h after administration. Given the high correlations between plasma and saliva, saliva samples may be offered as a sensitive surrogate for blood sampling to estimate adrenal and pituitary function.

Perioperative Glucocorticoid Therapy for Patients with Adrenal Insufficiency: Dosing Based on Pharmacokinetic Data

BACKGROUND

Perioperative glucocorticoid therapy for patients with adrenal insufficiency (AI) is currently based on anecdotal reports, without supporting pharmacokinetic data.

METHODS

We determined the half-life, clearance, and volume of distribution of 2 consecutive intravenously (IV)-administered doses of hydrocortisone (15 or 25 mg every 6 hours) to 22 dexamethasone-suppressed healthy individuals and used the data to develop a novel protocol to treat 68 patients with AI who required surgical procedures. Patients received 20 mg of hydrocortisone orally 2 to 4 hours before intubation and were started on 25 mg of IV hydrocortisone every 6 hours for 24 hours and 15 mg every 6 hours during the second day. Nadir cortisol concentrations were repeatedly measured during that period.

RESULTS

In healthy individuals, cortisol half-life was longer when the higher hydrocortisone dose was administered (2.02 ± 0.15 vs 1.81 ± 0.11 hours; P < 0.01), and in patients with AI, the half-life was longer than in healthy individuals given the same hydrocortisone dose. In both populations, the cortisol half-life increased further with the second hormone injection. Prolongation of cortisol half-life was due to decreased hydrocortisone clearance and an increase in its volume of distribution. Nadir cortisol levels determined throughout the 48 postoperative hours were within the range of values and often exceeded those observed perioperatively in patients without adrenal dysfunction.

CONCLUSIONS

Cortisol pharmacokinetics are altered in the postoperative period and indicate that lower doses of hydrocortisone can be safely administered to patients with AI undergoing major surgery. The findings of this investigation call into question the current practice of administering excessive glucocorticoid supplementation during stress.

Chronopharmacology of glucocorticoids

Glucocorticoids influence a wide array of metabolic, anti-inflammatory, immunosuppressive, and cognitive signaling processes, playing an important role in homeostasis and preservation of normal organ function. Synthesis is regulated by the hypothalamic-pituitary-adrenal (HPA) axis of which cortisol is the primary glucocorticoid in humans. Synthetic glucocorticoids are important pharmacological agents that augment the anti-inflammatory and immunosuppressive properties of endogenous cortisol and are widely used for the treatment of asthma, Crohn's disease, and rheumatoid arthritis, amongst other chronic conditions. The homeostatic activity of cortisol is disrupted by the administration of synthetic glucocorticoids and so there is interest in developing treatment options that minimize HPA axis disturbance while maintaining the pharmacological effects. Studies suggest that optimizing drug administration time can achieve this goal. The present review provides an overview of endogenous glucocorticoid activity and recent advances in treatment options that have further improved patient safety and efficacy with an emphasis on chronopharmacology.

Novel insights into glucocorticoid replacement therapy for pediatric and adult adrenal insufficiency

Adrenal insufficiency is defined as impaired adrenocortical hormone synthesis. According to its source, the deficit is classified as primary (adrenal steroidogenesis impairment), secondary (pituitary adrenocorticotropic hormone deficit) or tertiary (hypothalamic corticotropin-releasing hormone deficit). The management of adrenal insufficiency resides primarily in physiological replacement of glucocorticoid secretion. Standard glucocorticoid therapy is shrouded in several controversies. Along the difficulties arising from the inability to accurately replicate the pulsatile circadian cortisol rhythm, come the uncertainties of dose adjustment and treatment monitoring (absence of reliable biomarkers). Furthermore, side effects of inadequate replacement significantly hinder the quality of life of patients. Therefore, transition to circadian hydrocortisone therapy gains prominence. Recent therapeutic advancements consist of oral hydrocortisone modified-release compounds (immediate, delayed and sustained absorption formulations) or continuous subcutaneous hydrocortisone infusion. In addition to illustrating the current knowledge on conventional glucocorticoid regimens, this review outlines the latest research outcomes. We also describe the management of pediatric patients and suggest a novel strategy for glucocorticoid replacement therapy in adults.

Factors impacting on the action of glucocorticoids in patients receiving glucocorticoid therapy

Glucocorticoids (GCs) are steroid hormones, which are essential for life. They are secreted by the adrenal cortex under the control of the hypothalamic-pituitary-adrenal (HPA) axis. Glucocorticoids are essential for the normal function of most organ systems and, in both, excess and deficiency can lead to significant adverse consequences. Adrenal insufficiency (AI) is a rare, life-threatening disorder characterized by insufficient production of corticosteroid hormones. Primary AI is defined by the inability of the adrenal cortex to produce sufficient amounts of glucocorticoids and/or mineralocorticoids despite normal or increased adrenocorticotropin hormone (ACTH). Secondary AI is adrenal hypofunction due to insufficient amount of ACTH produced by the pituitary gland. Conventional treatment of both primary and secondary adrenal insufficiencies involves lifelong glucocorticoid replacement therapy. The role of cortisol deficiency and the impact of hydrocortisone replacement on morbidity and mortality in this patient group are under increasing scrutiny. Established glucocorticoid replacement regimens do not completely mirror endogenous hormonal production, and their monitoring to ensure optimum therapy is hampered by the lack of reliable biomarkers of hormone sufficiency. A further confounding issue is the tissue-specific regulation of glucocorticoid through the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) with research focusing on the role of this prereceptor regulation in the development of adverse metabolic features in patients. This review defines the factors influencing glucocorticoid action in patients with adrenal insufficiency receiving glucocorticoid therapy.

Therapeutic patient education in adrenal insufficiency

It is essential to encourage patient autonomy in the management of their illness, and notably their participation in treatment education programs; specific programs target avoidance or early preventive treatment of acute adrenal insufficiency, which is a life-threatening complication. Therapeutic patient education is recommended by the two international consensus statements on the management of primary adrenal insufficiency and the French consensus on adrenal insufficiency. Although there is no common international reference framework to date, the objective of the French consensus was to provide a frame of reference to facilitate the development of therapeutic education for patients with adrenal insufficiency. The principal educational objectives were: for the patient to always carry the necessary emergency equipment; be able to identify situations of increased risk and the early signs of adrenal crisis; know how to adjust oral glucocorticoid treatment; be capable of administering hydrocortisone by subcutaneous injection; be able to adjust treatment to different situations (heat, physical exercise, travel); and be able to appropriately use the resources of the healthcare services. Other programs could also be developed to respond to patients' needs and expectations, notably concerning hydrocortisone dose adjustment to avoid overdose in the context of chronic fatigue syndrome.

Pharmacokinetics of oral hydrocortisone - Results and implications from a randomized controlled trial

CONTEXT AND OBJECTIVE

This study aimed at comparing pharmacokinetics of two different doses of hydrocortisone (HC) in patients with secondary adrenal insufficiency (SAI).

DESIGN, SETTING AND PATIENTS

Forty-six patients with SAI participated in this randomized double-blind crossover study.

INTERVENTION

Patients received two different doses of HC (0.2-0.3mg HC/kg body weight/day and 0.4-0.6mg HC/kg body weight/day).

MAIN OUTCOME MEASURES

One- and two-compartment population models for plasma free cortisol, plasma total cortisol and salivary cortisol were parameterized. The individual pharmacokinetic parameters clearance (CL), volume of distribution (V_d), elimination half-life (t_1/2), maximum concentration (C_max), and area under the curve (AUC) were calculated.

RESULTS

The one-compartment models gave a better description of the data compared to the two-compartment models. Weight-adjusted dosing reduced variability in cortisol exposure with comparable AUCs between weight groups. However, there was large inter-individual variation in CL and V_d of plasma free cortisol, plasma total cortisol and salivary cortisol. As a consequence, AUC_24h varied more than 10 fold. Cortisol exposure was increased with the higher dose, but this was dose proportional only for free cortisol concentrations and not for total cortisol.

CONCLUSIONS

Cortisol concentrations after a doubling of the dose were only dose proportional for free cortisol. HC pharmacokinetics can differ up to 10-fold inter-individually and individual adjustment of treatment doses may be necessary. Doubling of the HC dose in fast metabolizers (patients that showed relative low AUC and thus high clearance compared to other patients), does not result in significantly enhanced exposure during large parts of the day and these patients may need other management strategies.

Salivary cortisol and cortisone in the clinical setting

PURPOSE OF REVIEW

A resurgence of interest in salivary biomarkers has generated evidence for their value in assessing adrenal function. The advantages of salivary measurements include only free hormone is detected, samples can be collected during normal daily routines and stress-induced cortisol release is less likely to occur than during venepuncture. We review the use of salivary biomarkers to diagnose and monitor patients for conditions of cortisol excess and deficiency and discuss the value of measuring salivary cortisone versus salivary cortisol.

RECENT FINDINGS

Developments in laboratory techniques have enabled the measurement of salivary hormones with a high level of sensitivity and specificity. In states of altered cortisol binding, salivary biomarkers are more accurate measures of adrenal reserve than serum cortisol. Salivary cortisone is a superior marker of serum cortisol compared with salivary cortisol, specifically when serum cortisol is low and during hydrocortisone therapy when contamination of saliva may result in misleading salivary cortisol concentrations.

SUMMARY

Salivary cortisol and cortisone can be used to assess cortisol excess, deficiency and hydrocortisone replacement, with salivary cortisone having the advantage of detection when serum cortisol levels are low and there is no interference from oral hydrocortisone.

The Functional and Clinical Significance of the 24-Hour Rhythm of Circulating Glucocorticoids

Adrenal glucocorticoids are major modulators of multiple functions, including energy metabolism, stress responses, immunity, and cognition. The endogenous secretion of glucocorticoids is normally characterized by a prominent and robust circadian (around 24 hours) oscillation, with a daily peak around the time of the habitual sleep-wake transition and minimal levels in the evening and early part of the night. It has long been recognized that this 24-hour rhythm partly reflects the activity of a master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus. In the past decade, secondary circadian clocks based on the same molecular machinery as the central master pacemaker were found in other brain areas as well as in most peripheral tissues, including the adrenal glands. Evidence is rapidly accumulating to indicate that misalignment between central and peripheral clocks has a host of adverse effects. The robust rhythm in circulating glucocorticoid levels has been recognized as a major internal synchronizer of the circadian system. The present review examines the scientific foundation of these novel advances and their implications for health and disease prevention and treatment.

Glucocorticosteroids do not impact directly growth rate and biomass of Rhizopus arrhizus (syn. R. oryzae) in vitro

Glucocorticoid (GC) use is a common risk factor for invasive fungal infections. This is attributed to the complex dysregulation of immunity caused by GCs. However, studies have demonstrated increased growth with GC exposure for some molds, such as Aspergillus fumigatus and Exserohilum rostratum. No such data exist for Mucorales. Therefore, we investigated the influence of GC exposure on the growth of Rhizopus arrhizus (syn. R. oryzae) in different culture media and in different atmospheres. We measured continuous spore growth using spectrophotometry and biomass variations using XTT assay. We did not observe enhanced growth or biomass variation with any of the GCs regardless of the medium or conditions. These results support the existence of fungus-specific differences in the effect of GCs on fungal biology.

Optimal glucocorticoid replacement in adrenal insufficiency

Adrenal insufficiency (glucocorticoid deficiency) comprises a group of rare diseases, including primary adrenal insufficiency, secondary adrenal insufficiency and congenital adrenal hyperplasia. Lifesaving glucocorticoid therapy was introduced over 60 years ago, but since then a number of advances in treatment have taken place. Specifically, little is known about short- and long-term treatment effects, and morbidity and mortality. Over the past decade, systematic cohort and registry studies have described reduced health-related quality of life, an unfavourable metabolic profile and increased mortality in patients with adrenal insufficiency, which may relate to unphysiological glucocorticoid replacement. This has led to the development of new modes of replacement that aim to mimic normal glucocorticoid physiology. Here, evidence for the inadequacy of conventional glucocorticoid therapy and recent developments in treatment are reviewed, with an emphasis on primary adrenal insufficiency.

Plasma, salivary and urinary cortisol levels following physiological and stress doses of hydrocortisone in normal volunteers

BACKGROUND

Glucocorticoid replacement is essential in patients with primary and secondary adrenal insufficiency, but many patients remain on higher than recommended dose regimens. There is no uniformly accepted method to monitor the dose in individual patients. We have compared cortisol concentrations in plasma, saliva and urine achieved following "physiological" and "stress" doses of hydrocortisone as potential methods for monitoring glucocorticoid replacement.

METHODS

Cortisol profiles were measured in plasma, saliva and urine following "physiological" (20 mg oral) or "stress" (50 mg intravenous) doses of hydrocortisone in dexamethasone-suppressed healthy subjects (8 in each group), compared to endogenous cortisol levels (12 subjects). Total plasma cortisol was measured half-hourly, and salivary cortisol and urinary cortisol:creatinine ratio were measured hourly from time 0 (between 0830 and 0900) to 5 h. Endogenous plasma corticosteroid-binding globulin (CBG) levels were measured at time 0 and 5 h, and hourly from time 0 to 5 h following administration of oral or intravenous hydrocortisone. Plasma free cortisol was calculated using Coolens' equation.

RESULTS

Plasma, salivary and urine cortisol at 2 h after oral hydrocortisone gave a good indication of peak cortisol concentrations, which were uniformly supraphysiological. Intravenous hydrocortisone administration achieved very high 30 minute cortisol concentrations. Total plasma cortisol correlated significantly with both saliva and urine cortisol after oral and intravenous hydrocortisone (P <0.0001, correlation coefficient between 0.61 and 0.94). There was no difference in CBG levels across the sampling period.

CONCLUSIONS

An oral dose of hydrocortisone 20 mg is supraphysiological for routine maintenance, while stress doses above 50 mg 6-hourly would rarely be necessary in managing acute illness. Salivary cortisol and urinary cortisol:creatinine ratio may provide useful alternatives to plasma cortisol measurements to monitor replacement doses in hypoadrenal patients.

9β Polymorphism of the glucocorticoid receptor gene appears to have limited impact in patients with Addison's disease

Background

Addison’s disease (AD) has been associated with an increased risk of cardiovascular disease. Glucocorticoid receptor polymorphisms that alter glucocorticoid sensitivity may influence metabolic and cardiovascular risk factors in patients with AD. The 9β polymorphism of the glucocorticoid receptor gene is associated with relative glucocorticoid resistance and has been reported to increase the risk of myocardial infarction in the elderly. We explored the impact of this polymorphism in patients with AD.

Materials and Methods

147 patients with AD and 147 age, gender and ethnicity matched healthy controls were recruited. Blood was taken in a non-fasted state for plasma lipid determination, measurement of cardiovascular risk factors and DNA extraction.

Results

Genotype data for the 9β polymorphism was available for 139 patients and 146 controls. AD patients had a more atherogenic lipid profile characterized by an increase in the prevalence of small dense LDL (p = 0.003), increased triglycerides (p = 0.002), reduced HDLC (p<0.001) an elevated highly sensitive C-reactive protein (p = 0.01), compared with controls. The 9β polymorphism (at least one G allele) was found in 28% of patients and controls respectively. After adjusting for age, gender, ethnicity, BMI and hydrocortisone dose per metre square of body surface area in patients, there were no significant metabolic associations with this polymorphism and hydrocortisone doses were not higher in patients with the polymorphism.

Conclusions

This study did not identify any associations between the 9β polymorphism and cardiovascular risk factors or hydrocortisone dose and determination of this polymorphism is therefore unlikely to be of clinical benefit in the management of patients with AD.

Therapy of adrenal insufficiency: an update

Adrenal insufficiency may be caused by the destruction or altered function of the adrenal gland with a primary deficit in cortisol secretion (primary adrenal insufficiency) or by hypothalamic-pituitary pathologies determining a deficit of ACTH (secondary adrenal insufficiency). The clinical picture is determined by the glucocorticoid deficit, which may in some conditions be accompanied by a deficit of mineralcorticoids and adrenal androgens. The substitutive treatment is aimed at reducing the signs and symptoms of the disease as well as at preventing the development of an addisonian crisis, a clinical emergency characterized by hypovolemic shock. The oral substitutive treatment should attempt at mimicking the normal circadian profile of cortisol secretion, by using the lower possible doses able to guarantee an adequate quality of life to patients. The currently available hydrocortisone or cortisone acetate preparations do not allow an accurate reproduction of the physiological secretion pattern of cortisol. A novel dual-release formulation of hydrocortisone, recently approved by EMEA, represents an advancement in the optimization of the clinical management of patients with adrenal insufficiency. Future clinical trials of immunomodulation or immunoprevention will test the possibility to delay (or prevent) the autoimmune destruction of the adrenal gland in autoimmune Addison's disease.

What is the best approach to tailoring hydrocortisone dose to meet patient needs in 2012?

Cortisol is an essential stress hormone and replacement with oral hydrocortisone is lifesaving in patients with adrenal insufficiency. Cortisol has a diurnal rhythm regulated by the central body clock and this rhythm is a metabolic signal for peripheral tissue clocks. Loss of cortisol rhythmicity is associated with fatigue, depression and insulin resistance. A general principle in endocrinology is to replace hormones to replicate physiological concentrations; however, the pharmacokinetics of oral immediate-release hydrocortisone make it impossible to fully mimic the cortisol rhythm and patients still have an increased morbidity and mortality despite replacement. Traditionally, physicians have replaced hydrocortisone with a total daily dose based on the diurnal 24-h cortisol production rate with hydrocortisone given twice or thrice daily, with the highest dose first thing in the morning. Monitoring treatment and dose titration has been much debated with some clinicians using cortisol day curves and others relying on clinical symptoms. The main challenge is that there is no established biomarker of cortisol activity. In addressing the clinical question, we have taken the view that an understanding of the cortisol circadian rhythm and hydrocortisone pharmacokinetics is essential when tailoring hydrocortisone dose. Using this approach, we have developed a thrice daily, weight-related, dosing regimen and a pharmacokinetic and clinical method to monitor treatment. Our argument for replicating the cortisol circadian rhythm is based on the observation that disruption of the rhythm is associated with ill health, and the few studies that have compared different treatment regimens. Further studies are required to definitively test the benefits of replacing the cortisol circadian rhythm in patients with adrenal insufficiency.

Assessment of glucocorticoid therapy with salivary cortisol in secondary adrenal insufficiency

CONTEXT

Appropriate glucocorticoid replacement therapy in adrenal insufficiency (AI) is crucial, given the risks of chronic under- or overtreatment, particularly in patients on multiple medications. Salivary sampling allows for non-invasive, stress-free cortisol measurement.

OBJECTIVE

To determine whether salivary cortisol measurement is helpful in assessing the adequacy of glucocorticoid therapy with cortisone acetate (CA) in patients with secondary AI.

DESIGN

A prospective cohort study at the Endocrinology Unit of Padua University Hospital.

METHODS

Six samples of salivary cortisol were collected from 28 patients with secondary AI on CA treatment and from 36 healthy volunteers at fixed times of the day, and used to calculate salivary cortisol levels at each time point and the area under the curve (AUC) across the different sampling times.

RESULTS

Salivary cortisol levels were lower in patients than in controls in the morning but no differences were found in the afternoon or at night before resting. Salivary cortisol levels were higher in patients immediately following CA administration. Ten patients showed an AUC above the 97.5th percentile of controls, without clinical signs of hypercortisolism, and salivary cortisol levels 90 min after each dose of CA predict the AUC. All patients had severe GH deficiency and there were no differences in salivary cortisol levels or AUC between patients treated or not with GH.

CONCLUSIONS

Two salivary cortisol determinations, able to predict the daily AUC, may allow for assessing the adequacy of glucocorticoid replacement therapy in secondary AI and for identifying cases of over- or undertreatment.

Regulation of cortisol bioavailability--effects on hormone measurement and action

Routine assessment of the hypothalamic-pituitary-adrenal axis relies on the measurement of total serum cortisol levels. However, most cortisol in serum is bound to corticosteroid-binding globulin (CBG) and albumin, and changes in the structure or circulating levels of binding proteins markedly affect measured total serum cortisol levels. Furthermore, high-affinity binding to CBG is predicted to affect the availability of cortisol for the glucocorticoid receptor. CBG is a substrate for activated neutrophil elastase, which cleaves the binding protein and results in the release of cortisol at sites of inflammation, enhancing its tissue-specific anti-inflammatory effects. Further tissue-specific modulation of cortisol availability is conferred by corticosteroid 11β-dehydrogenase. Direct assessment of tissue levels of bioavailable cortisol is not clinically practicable and measurement of total serum cortisol levels is of limited value in clinical conditions that alter prereceptor glucocorticoid bioavailability. Bioavailable cortisol can, however, be measured indirectly at systemic, extracellular tissue and cell levels, using novel techniques that have provided new insight into the transport, metabolism and biological action of glucocorticoids. A more physiologically informative approach is, therefore, now possible in the assessment of the hypothalamic-pituitary-adrenal axis, which could prove useful in clinical practice.

Measurement of salivary cortisol in 2012 - laboratory techniques and clinical indications

The utility of measuring salivary cortisol has become increasingly appreciated since the early 1980s. Salivary cortisol is a measure of active free cortisol and follows the diurnal rhythm of serum or plasma cortisol. The saliva sample may be collected by drooling or through the use of absorbent swabs which are placed into the mouth until saturated. Salivary cortisol is therefore convenient for patients and research participants to collect noninvasively on an outpatient basis. Several assay techniques have been used to measure salivary cortisol, including radioimmunoassay and more recently liquid chromatography-tandem mass spectrometry. The analytical sensitivity varies between these assay methods, as does the potential for cross-reactivity with other steroids. The interpretation of salivary cortisol levels relies on rigorous standardization of sampling equipment, sampling protocols and assay technology with establishment of a local reference range. Clinically, the commonest use for salivary cortisol is measuring late-night salivary cortisol as a screening test for Cushing's syndrome. Several studies have shown diagnostic sensitivities and specificities of over 90%, which compares very favourably with other screening tests for Cushing's syndrome such as the 24-h urinary-free cortisol and the 1-mg overnight dexamethasone suppression test. There are emerging roles for the use of salivary cortisol in diagnosing adrenal insufficiency, particularly in conditions associated with low cortisol-binding globulin levels, and in the monitoring of glucocorticoid replacement. Finally, salivary cortisol has been used extensively as a biomarker of stress in a research setting, especially in studies examining psychological stress with repeated measurements.

Corticosteroid-binding globulin regulates cortisol pharmacokinetics

OBJECTIVE

Corticosteroid-binding globulin (CBG) is the principal carrier for cortisol in the circulation. Variations in CBG-binding capacity are predicted to alter total serum cortisol disposition, but free serum cortisol is believed to be unaffected. Unbound cortisol pharmacokinetics (PK) have not been studied in the context of CBG changes. We aimed to assess the regulation of cortisol PK by CBG.

DESIGN AND SUBJECTS

Women on oestrogens [oral contraceptive pill, (OCP)], patients homozygous for a nonfunctioning CBG variant (CBG null) and healthy controls (HV) were studied before and after IV and oral administration of hydrocortisone 20 mg.

MEASUREMENTS

PK parameters were studied for total serum cortisol (SerF), free serum cortisol (FreeF) and cortisone (FreeE), and salivary cortisol (SalF) and cortisone (SalE): area under the curve (AUC), clearance (CL), half-life and volume of distribution (V(d)).

RESULTS

Following IV hydrocortisone, AUC and half-life of SerF were significantly higher in the OCP group and lower in the CBG null. SerF CL and V(d) were significantly lower in the OCP group and increased in the CBG null, compared to HV. PK parameters for FreeF and the salivary biomarkers were not different between the CBG null and HV, although OCP patients still had higher AUC compared to HV and prolonged half-life. These findings were confirmed following oral hydrocortisone, but concentration-time profiles were highly heterogeneous and SalF interpretation was problematic because of oral contamination.

CONCLUSIONS

We have demonstrated that CBG has a distinct effect on cortisol PK. When CBG binding is disrupted, FreeF retains normal PK characteristics, although CBG null patients lack a CBG-bound pool of readily releasable cortisol. Women on oestrogens may have altered free serum cortisol kinetics and thus may be potentially overexposed to glucocorticoids.

Adverse effect of phenytoin on glucocorticoid replacement in a child with adrenal insufficiency

Chronic administration of antiepileptic agents such as phenytoin can increase clearance rates of cortisol and synthetic glucocorticoids through hepatic microsomal enzyme induction. However, data concerning an adverse interaction between antiepileptic and steroid drugs are scarce. We herein report an adolescent boy with primary adrenal insufficiency that developed glucocorticoid deficiency after added phenytoin treatment. The patient had an increased requirement for hydrocortisone replacement, and two episodes of vomiting, hyponatremia and mild hypoglycemia. His ACTH levels were markedly elevated. Fifteen days after stopping phenytoin, his serum ACTH concentration returned to normal range. Even though the hydrocortisone dose was gradually decreased, hyponatremia and vomiting have not recurred. In conclusion, we suggest that drugs such as phenytoin affecting hepatic clearance of synthetic glucocorticoids and mineralocorticoids should not be preferred for therapy in patients with adrenal insufficiency. If their use is vital, one should be aware of increased replacement requirements for steroid drugs, and patients should be closely monitored.

Utility of salivary cortisol measurements in Cushing's syndrome and adrenal insufficiency

CONTEXT

The measurement of cortisol in saliva is a simple, reproducible, and reliable test to evaluate the normal and disordered control of the hypothalamic-pituitary-adrenal (HPA) axis. There are a variety of simple methods to obtain saliva samples without stress, making this a robust test applicable to many different experimental and clinical situations.

EVIDENCE ACQUISITION

Ovid Medline and PubMed from 1950 to present were searched using the following strategies: [<saliva or salivary>and<cortisol or hydrocortisone>and<Cushing or Cushing's>] and [<saliva or salivary>and<cortisol or hydrocortisone>and<adrenal insufficiency or hypoadrenalism or hypopituitarism or Addison's disease>]. The bibliographies of all relevant citations were evaluated for any additional appropriate citations.

EVIDENCE SYNTHESIS

Measurement of an elevated late-night (2300 to 2400 h) salivary cortisol has a greater than 90% sensitivity and specificity for the diagnosis of endogenous Cushing's syndrome. Late-night salivary cortisol measurements are also useful to monitor patients for remission and/or recurrence after pituitary surgery for Cushing's disease. Because it is a surrogate for plasma free cortisol, the measurement of salivary cortisol may be useful during an ACTH stimulation test in patients with increased plasma binding protein concentrations due to increased estrogen, or decreased plasma binding protein concentrations during critical illness. Most reference laboratories now offer salivary cortisol testing.

CONCLUSIONS

It is expected that the use of the measurement of salivary cortisol will become routine in the evaluation of patients with disorders of the HPA axis.

Inadequacies of glucocorticoid replacement and improvements by physiological circadian therapy

Patients with adrenal insufficiency need lifelong glucocorticoid replacement, but many suffer from poor quality of life, and overall there is increased mortality. Moreover, it appears that use of glucocorticoids at the higher end of the replacement dose range is associated with increased risk for cardiovascular and metabolic bone disease. These data highlight some of the inadequacies of current regimes. The cortisol production rate is estimated to be equivalent to 5.7-7.4 mg/m(2) per day, and a major difficulty for replacement regimes is the inability to match the distinct circadian rhythm of circulating cortisol levels, which are low at the time of sleep onset, rise between 0200 and 0400 h, peaking just after waking and then fall during the day. Another issue is that current dose equivalents of glucocorticoids used for replacement are based on anti-inflammatory potency, and few data exist as to doses needed for equivalent cardiovascular and bone effects. Weight-adjusted, thrice-daily dosing using hydrocortisone (HC) reduces glucocorticoid overexposure and represents the most refined regime for current oral therapy, but does not replicate the normal cortisol rhythm. Recently, proof-of-concept studies have shown that more physiological circadian glucocorticoid therapy using HC infusions and newly developed oral formulations of HC have the potential for better biochemical control in patients with adrenal insufficiency. Whether such physiological replacement will have an impact on the complications seen in patients with adrenal insufficiency will need to be analysed in future clinical trials.

Novel strategies for hydrocortisone replacement

Current therapy with immediate-release hydrocortisone is the most commonly used regimen for replacement in patients with primary and secondary adrenal insufficiency. However, conventional hydrocortisone cannot provide the physiological rhythm of cortisol release. Physicians have used fixed twice- or thrice-daily doses, but these regimens inevitably result in temporary over- or under-replacement. Patients with adrenal insufficiency, although on treatment, have a poor quality of life and an increased mortality. Optimization of current treatment has been attempted with thrice-daily, weight-related dosing, but this still fails to simulate the normal diurnal rhythm of cortisol. Recent research has investigated circadian hydrocortisone therapy imitating the physiological cortisol rhythm. Proof-of-concept studies using hydrocortisone infusions predict improvements in biochemical control and quality of life. Now delayed and sustained release oral formulations of hydrocortisone are being developed, and these offer a more practical and effective solution for patients with adrenal insufficiency and congenital adrenal hyperplasia.

Salivary steroid assays – research or routine?

Salivary concentrations of unconjugated steroids reflect those for free steroids in serum although concentrations may differ because of salivary gland metabolism. Samples for salivary steroid analysis are stable for up to 7 days at room temperature, one month or more at 4°C and three months or more at −20°C. When assessed against strict criteria, the evidence shows that salivary cortisol in evening samples or following dexamethasone suppression provides a reliable and effective screen for Cushing's syndrome. Sequential salivary cortisol measurements are also extremely helpful for the investigation of suspected cyclical Cushing's syndrome. There is potential for the identification of adrenal insufficiency when used with Synacthen stimulation. Salivary 17-hydroxyprogesterone and androstenedione assays are valued as non-invasive tests for the home-monitoring of hydrocortisone replacement therapy in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. The diagnostic value of salivary oestradiol, progesterone, testosterone, dehydroepiandrosterone and aldosterone testing is compromised by rapid fluctuations in salivary concentrations of these steroids. Multiple samples are required to obtain reliable information, and at present the introduction of these assays into routine laboratory testing is not justified.

Matrix metalloproteinase-13 is required for zebra fish (Danio rerio) development and is a target for glucocorticoids

Matrix metalloproteinases (MMPs) are endopeptidases that degrade the proteins of the extracellular matrix (ECM). Expression and activity of the MMPs are essential for embryogenesis, where MMPs participate in the normal ECM remodeling that occurs during tissue morphogenesis and development. Studies have demonstrated that MMP gene expression is inhibited by glucocorticoids in mammalian cell culture systems and that exposure to glucocorticoids causes developmental abnormalities in several species. Therefore, we proposed that glucocorticoids impede normal development through alteration of MMP expression. Zebra fish (Danio rerio) were used as a model to study MMP-13 expression both during normal embryogenesis and following acute exposure to two glucocorticoids, dexamethasone, and hydrocortisone. MMP-13 is one of three collagenases identified in vertebrates that catalyzes the degradation of type I collagens at neutral pH. MMP-13 expression varied during zebra fish development, with peak expression at 48 h post-fertilization (hpf). Morpholino knockdown studies showed that MMP-13 expression is necessary for normal zebra fish embryogenesis. Acute exposure to dexamethasone and hydrocortisone resulted in abnormal zebra fish development including craniofacial abnormalities, altered somitogenesis, blood pooling and pericardial and yolk sac edema as well as increased MMP-13 mRNA and activity at 72 hpf. In situ hybridization experiments were used to confirm the increase in MMP-13 expression following glucocorticoid treatment and showed elevated MMP-13 expression in the rostral trunk, brain, eye, heart, and anterior kidney of treated embryos. These data demonstrate that normal zebra fish embryogenesis requires MMP-13 and that dexamethasone and hydrocortisone modulate the expression of this gene, leading to increased activity and potentially contributing to subsequent dysmorphogenesis.