Acute adrenal insufficiency in a patient with asthma after changing from fluticasone propionate to budesonide

Metabolomic profiling reveals extensive adrenal suppression due to inhaled corticosteroid therapy in asthma

The application of large-scale metabolomic profiling provides new opportunities for realizing the potential of omics-based precision medicine for asthma. By leveraging data from over 14,000 individuals in four distinct cohorts, this study identifies and independently replicates 17 steroid metabolites whose levels were significantly reduced in individuals with prevalent asthma. Although steroid levels were reduced among all asthma cases regardless of medication use, the largest reductions were associated with inhaled corticosteroid (ICS) treatment, as confirmed in a 4-year low-dose ICS clinical trial. Effects of ICS treatment on steroid levels were dose dependent; however, significant reductions also occurred with low-dose ICS treatment. Using information from electronic medical records, we found that cortisol levels were substantially reduced throughout the entire 24-hour daily period in patients with asthma who were treated with ICS compared to those who were untreated and to patients without asthma. Moreover, patients with asthma who were treated with ICS showed significant increases in fatigue and anemia as compared to those without ICS treatment. Adrenal suppression in patients with asthma treated with ICS might, therefore, represent a larger public health problem than previously recognized. Regular cortisol monitoring of patients with asthma treated with ICS is needed to provide the optimal balance between minimizing adverse effects of adrenal suppression while capitalizing on the established benefits of ICS treatment.

Baseline and peak cortisol response to the low dose short Synacthen test relates to indication for testing, age and sex

Objective

To review the outcomes of a simplified low dose Synacthen test (LDSST) performed in a tertiary endocrine service over seven years, and to examine for relationships between cortisol measurements and indication for testing, age and sex.

Design

Retrospective, observational study of LDSST performed in 2008 – 2014 (N=335) and 2016-2020 (N=160).

Methods

LDSST were performed by endocrine nurses. Synacthen 500ng/1.73m 2 administered as IV bolus, sampling at 0, 15, 25 and 35 minutes.

Results

Mean (± 1SD) baseline cortisol was 221 ± 120 nmol/L, peak 510 ± 166nmol/L and increment 210 ± 116 nmol/L. 336 (70%) of patients had a normal response (baseline cortisol >100nmol/L, peak >450nmol/L), 78 (16%) a suboptimal response (peak cortisol 350-450nmol/L) and were prescribed hydrocortisone to during periods of stress only, 67 (14%) an abnormal response (baseline <100nmol/L or peak <350nmol/L) and were prescribed daily hydrocortisone. Basal, peak and incremental increases in cortisol were higher in females (p=0.03, p<0.001, p=0.03 respectively). Abnormal results occurred most frequently in patients treated previously with pharmacological doses of glucocorticoids or structural brain abnormalities (p<0.0001).

Discussion

There are concerns that the specificity of the LDSST is poor. The low prevalence and strong association of abnormal results with indication for testing, suggests that over diagnosis occurred infrequently in this clinical setting.

Recovery of hypothalamo-pituitary-adrenal axis suppression during treatment with inhaled corticosteroids for childhood asthma

Objective

To describe recovery of adrenal insufficiency in asthmatic children treated with inhaled corticosteroids (ICS) and cortisol replacement therapy.

Design

Retrospective, observational study.

Patients

A total of 113 patients, 74 male; age 10.4 (3.3–16.5) years; beclomethasone-equivalent ICS dose, 800 μg, (100–1,000), tested by low dose short Synacthen (tetracosactide) test (LDSST), were studied. Test results were classified by basal and peak cortisol concentration: “normal” (basal >100 nmol/L, peak >500 nmol/L), “suboptimal” (basal >100 nmol/L, peak 350–499 nmol/L), “abnormal” (basal <100 nmol/L and/or peak <350 nmol/L). Patients with suboptimal results received hydrocortisone during periods of stress only, and those with abnormal responses received daily hydrocortisone, increased during periods of stress. A total of 73 patients (68%) had ≥2 LDSSTs over 2.2 years (0.2–7.7).

Measurements

Change in cortisol response to repeat LDSST (movement between diagnostic groups, difference in basal and peak cortisol >15% [2× the inter-assay coefficient of variation]), change in BMI and height standard deviation score (SDS).

Results

Baseline test results were abnormal in 17 patients (15%) and all of them had repeat tests. In 13 patients (76%), test results improved (normal in six, suboptimal in seven) and four (24%) remained abnormal. Baseline tests results were suboptimal in 54 patients (48%), of whom 50 (93%) were retested. Repeat tests were normal in 36 patients (72%), remained suboptimal in 11 (22%), and were abnormal in three (6%). Baseline tests results were normal in 42 patients, of whom six patients (14%) were retested. Results remained normal in three (50%), were suboptimal in two (33%), and abnormal in one (17%). Basal and peak cortisol levels increased by >15% in 33/73 (45%) and 42/73 (57%) patients, respectively, and decreased by >15% in 14/73 (19%) and 7/73 (10%), respectively. There was no significant change in height or BMI SDS.

Conclusion

Recovery of adrenal function is common and occurs during continued ICS and cortisol replacement therapy.

The use of inhaled corticosteroids in pediatric asthma: update

Despite the availability of several formulations of inhaled corticosteroids (ICS) and delivery devices for treatment of childhood asthma and despite the development of evidence-based guidelines, childhood asthma control remains suboptimal. Improving uptake of asthma management plans, both by families and practitioners, is needed. Adherence to daily ICS therapy is a key determinant of asthma control and this mandates that asthma education follow a repetitive pattern and involve literal explanation and physical demonstration of the optimal use of inhaler devices. The potential adverse effects of ICS need to be weighed against the benefit of these drugs to control persistent asthma especially that its safety profile is markedly better than oral glucocorticoids. This article reviews the key mechanisms of inhaled corticosteroid action; recommendations on dosage and therapeutic regimens; potential optimization of effectiveness by addressing inhaler technique and adherence to therapy; and updated knowledge on the real magnitude of adverse events.

Intermittent steroid inhalation for the treatment of childhood asthma

Inhaled corticosteroids have long been considered a mainstay of therapy for asthma in children. However, concerns over long-term side effects of chronic steroid administration have led providers to turn to intermittent dosing of these medications in an attempt to treat exacerbations while limiting total corticosteroid received. The data have been somewhat mixed in this area, likely at least partially due to the difficulty providers have in classifying asthma phenotypes in young children. This review will analyze the evidence for chronic daily inhaled corticosteroid use, intermittent inhaled corticosteroid use, and dynamic dosing approaches utilizing inhaled corticosteroid/long-acting beta agonist combination therapy.

Early morning salivary cortisol and cortisone, and adrenal responses to a simplified low-dose short Synacthen test in children with asthma

OBJECTIVE

To examine serum cortisol responses to a simplified low-dose short Synacthen test (LDSST) in children treated with inhaled corticosteroids (ICS) for asthma and to compare these to early morning salivary cortisol (EMSC) and cortisone (EMSCn) levels.

DESIGN

Early morning salivary cortisol and EMSCn samples were collected for three consecutive days. On day three, Synacthen 500 ng/1·73 m(2) was administered intravenously. Samples were collected at 0, 15, 25, 35 min.

RESULTS

A total of 269 subjects (160 M: 109 F), median (range) age 10·0 (5·1-15·2) years were studied. Peak cortisol in the LDSST was <500 nmol/l in 101 subjects (37·5%) and <350 nmol/l in 12 subjects (4·5%). Basal cortisol correlated with peak cortisol: r = 0·55, (95% CI: 0·46, 0·63, P < 0·0001). Time at which peak cortisol concentration was achieved was significantly related to the value of peak cortisol (P < 0·0001), with higher cortisol peaks occurring later in the test and lower cortisol peaks occurring earlier. EMSC and EMSCn had no predictive value for the identification of patients with a peak cortisol <500 nmol/l. EMSCn was superior to EMSC in identifying patients with a peak cortisol <350 nmol/l: a minimum EMSCn cut-off value of 12·5 nmol/l gave a negative predictive value of 99·2% and positive predictive value of 30·1%.

CONCLUSION

Our data illustrate that basal measures of cortisol are likely to be of value in screening populations for patients at greatest risk of adrenal crisis. EMSCn shows promise as a screening tool for the identification of patients with severe adrenal insufficiency.

Inhaled corticosteroids and secondary adrenal insufficiency

Inhaled corticosteroids (ICS) have been used as first line treatment of asthma for many decades. ICS are a form of exogenous glucocorticosteroids that can suppress the endogenous production of glucocorticosteroids, a condition known as adrenal suppression (AS). As a result, cessation, decreasing the dose or changing the type of ICS may trigger features of adrenal insufficiency (AI). AI may cause a spectrum of presentations varying from vague symptoms of fatigue to potentially life threatening acute adrenal crises. This article reviews the current literature on ICS and AI particularly in adults (although majority of data available is from the paediatric population). It aims to increase awareness of the potential risk of AI associated with ICS use, delineate the pathogenesis of AI and to provide recommendations on screening and management. From our literature review, we have found numerous case reports that have shown an association between ICS and AI particularly in children and patients using high doses. However, there have also been reports of AI in adults as well as in patients using low to moderate doses of ICS. To conclude, we recommend screening for AI in select patient groups with an initial early morning serum cortisol. If results are abnormal, more definitive testing such as the low dose corticotropin stimulation test may be done to confirm the diagnosis.

Moderate dose inhaled corticosteroid-induced symptomatic adrenal suppression: case report and review of the literature

Inhaled corticosteroids (ICS) are drugs of choice for persistent asthma. Less than 500 µg/d of fluticasone are believed to be safe. We found 92 cases of adrenal suppression in PubMed; among these cases there were 13 children who took 500 µg/d or less of fluticasone. Adrenal insufficiency was diagnosed in a 7-year-old boy on 460 µg ICS for 16 months, with a diagnosis of chronic persistent asthma. A random cortisol was nondetectable as was an early morning cortisol. ICS have greatly improved the day-to-day lives of children with chronic persistent asthma. Parents of children younger than 12 years, who use at least 400 µg of inhaled fluticasone (or bioequivalent), must be given oral and written instructions about warning symptoms of hypocortisolism. Major stress such as surgery, gastrointestinal, bronchopulmonary, or other systemic infections, and heat stress may mandate a written plan of action for use by hospital physicians.

Safety of inhaled budesonide: clinical manifestations of systemic corticosteroid-related adverse effects

Inhaled corticosteroid (ICS) therapy is central to the long-term management of asthma and is extensively used in the management of chronic obstructive pulmonary disease (COPD). While administration via inhalation limits systemic exposure compared with oral or injected corticosteroids and, therefore, the risk of systemic corticosteroid-related adverse effects, concerns over the long-term safety of ICS persist. The assessment of the long-term effects of ICS therapy requires considerable research effort over years or even decades. Surrogate markers/predictors for clinical endpoints such as adrenal crisis, reduced final height and fractures have been identified for use in relatively short-term studies. However, the predictive value of such markers remains questionable.Inhaled budesonide has been available since the early 1980s and there is a considerable evidence base investigating the safety of this agent. To assess the long-term safety of inhaled budesonide therapy in terms of the actual incidence of the clinical endpoints adrenal crisis/insufficiency, reduced final height, fractures and pregnancy complications, we undertook a review of the scientific literature. The external databases BIOSIS, Cochrane Central Register of Controlled Trials, Current Contents, EMBASE, International Pharmaceutical Abstracts and MEDLINE were searched, in addition to AstraZeneca's internal product literature database Planet, up to 29 February 2008. Only original articles of epidemiological studies, national surveys, clinical trials and case reports concerning inhaled budesonide were included.Eight surveys of adrenal crisis were found. The only survey with specified criteria for diagnosis involved 2912 paediatricians and endocrinologists and revealed 33 patients with adrenal crisis associated with ICS therapy; only one patient used budesonide (in co-treatment with fluticasone propionate). In addition, 14 case reports of adrenal crisis in budesonide-treated patients were found. In only two of these, budesonide was used at recommended doses and in the absence of interacting medication.Three retrospective studies and one prospective study assessing final height were found. None of them showed any reduced final height in patients receiving inhaled budesonide during childhood or adolescence.Seventeen epidemiological studies investigating the risk of fractures were found. When adjusting for confounding factors, they did not provide any unequivocal data for an increased fracture risk with budesonide. Four prospective placebo-controlled clinical trials of 2-6 years duration with inhaled budesonide in patients with asthma or COPD were found. None of the studies identified any association between inhaled budesonide and increased risk for fractures.Four studies using data from the Swedish birth and health registries showed there was no increased risk for congenital malformations, cardiovascular defects, decreased gestational age, birth weight or birth length among infants born to women using inhaled budesonide during pregnancy compared with the general population. This was confirmed by five observational studies in Australia, Canada, Hungary, Japan and the US. Similarly, one randomized clinical trial comparing pregnancy outcomes among asthma patients receiving inhaled budesonide or placebo did not demonstrate any difference in outcome of pregnancy.In summary, based on 25 years of experience with different doses and in different populations, inhaled budesonide therapy only in very rare cases appears to be associated with an increased risk of adrenal crisis, reduction in final height, increases in the number of fractures or complications during pregnancy.

Adrenal function in children with severe asthma treated with high-dose inhaled glucocorticoids: recommended screening tests in outpatient conditions

BACKGROUND

A number of previous studies have suggested that adrenal suppression occurs in asthmatic children treated with high-doses of inhaled glucocorticoids (IGC). This study was designed to determine the frequency of adrenal suppression in children with severe asthma treated with recommended doses of IGC: namely 500-1,000 microg/day of fluticasone propionate or the equivalent of budesonide (1,000-2,000 microg/day) for a period of at least 12 months.

METHODS

Early morning cortisol (F) and ACTH serum levels were measured in 27 severe asthmatics aged 6-16 years old. The children underwent a low dose ACTH test (1 microg/1.73 m2) with a parallel glucose measurement. Twenty-four hour urine collection was performed before examination for free F (UfF) and creatinine levels. There were no clinical manifestations of adrenal hypofunction in the analyzed children.

RESULTS

Of the 27 patients, 22 had normal basal and post-stimulatory levels of F and normal UfF, and the other five (18.5%) had basal serum F levels of <400 nmol/l. Four of the five also had normal post-stimulatory levels of F and normal UfF. One child had a subnormal peak F value of 484 nmol/l during the ACTH test. None of the patients had a suppressed serum ACTH level, but an elevated ACTH level was found in four children. This study provided biochemical evidence of suboptimal adrenal function in one child in the examined group (3.7%) and a good response to stimulation in all the others, even in those with slightly reduced basal cortisol levels.

CONCLUSION

This study showed that the use of fluticasone in doses of up to 1,000 microg/day (or the equivalent of budesonide) as long-term treatment of children with severe asthma did not substantially affect their adrenal function.

Oral and inhaled corticosteroids and adrenal insufficiency: a case-control study

BACKGROUND

Adrenal insufficiency, a well recognised complication of treatment with oral corticosteroids, has been described in association with inhaled corticosteroid use in over 60 case reports. The risk of adrenal insufficiency in people prescribed an oral or inhaled corticosteroid in the general population is not known. A study was undertaken to quantify the association between adrenal insufficiency and oral and inhaled corticosteroid exposure.

METHODS

A case-control study was performed using computerised general practice data from The Health Improvement Network.

RESULTS

From a cohort of 2.4 million people, 154 cases of adrenal insufficiency and 870 controls were identified. There was a dose related increased risk of adrenal insufficiency in people prescribed an oral corticosteroid with an odds ratio of 2.0 (95% CI 1.6 to 2.5) per course of treatment per year. Adrenal insufficiency was associated with a prescription for an inhaled corticosteroid during the 90 day period before the diagnosis with an odds ratio of 3.4 (95% CI 1.9 to 5.9) and this effect was dose related (p for trend <0.001). After adjusting for oral corticosteroid exposure, this odds ratio was reduced to 1.6 (95% CI 0.8 to 3.2) although the dose relation remained (p for trend 0.036).

CONCLUSION

People prescribed an oral or inhaled corticosteroid are at a dose related increased risk of adrenal insufficiency although the absolute risk is small. This analysis suggests that the increased risk in people prescribed an inhaled corticosteroid is largely due to oral corticosteroid exposure, but inhaled corticosteroids may have an effect when they are taken at higher doses.

The effect of a steroid "burst" and long-term, inhaled fluticasone propionate on adrenal reserve

BACKGROUND

Although widely used, the effects of steroid "bursts" on the hypothalamic-pituitary-adrenal axis, especially with long-term, concomitant topical steroids use, have not been studied.

OBJECTIVE

To examine the effect of a prednisone burst, long-term intranasal steroids, and inhaled fluticasone propionate on the suppression and recovery of adrenal function.

METHODS

Adult patients taking long-term intranasal steroids, either moderate-dose (440 microg/d) or high-dose (880 microg/d) inhaled fluticasone propionate, underwent a low-dose cosyntropin stimulation test (LDCST) before and 2 days after a prednisone burst. Suppressed adrenal responses were monitored with a weekly LDCST. Persistent abnormal LDCST results were confirmed by 8-hour cosyntropin infusion. Inhaled fluticasone dosages were decreased; adrenal recovery was evaluated by a monthly LDCST. Adverse effects of steroids were monitored by questionnaires.

RESULTS

Sixty-three patients participated in the study. Three of 31 patients not taking inhaled steroids and 1 of 13 patients taking moderate-dose fluticasone had abnormal LDCST results on day 2 after the prednisone burst, which normalized by the second week. In the high-dose fluticasone group, 14 of 19 patients had suppressed LDCST responses on day 2 and adrenal function recovered in 10 of 19 patients by the fourth week. These patients complained significantly of decreased libido (P = 0.02), listlessness (P = 0.03), and weight loss (P = 0.05). High-dose fluticasone (r = 0.66, P < 0.001) and duration of use (r = 0.32, P = 0.01) were statistically correlated with adrenal impairment. Of the 4 patients with persistent adrenal impairment, 3 patients successfully reduced dosages of inhaled fluticasone and adrenal function recovered in 2 to 10 months.

CONCLUSIONS

Prednisone bursts induce brief adrenal impairment. Intranasal steroids and moderate-dose fluticasone had no effect on adrenal function. High-dose, inhaled fluticasone caused mild-to-significant adrenal suppression and delayed the recovery after a steroid burst. Avoiding or limiting the duration of high-dose inhaled steroids would minimize systemic adverse effects.

Anti-inflammatory treatment for recurrent wheezing in the first five years of life

Medications identified for the treatment of recurrent wheezing in preschool children by the Expert Panel Report of the NHLBI Guidelines for the Diagnosis and Management of Asthma include inhaled corticosteroids, chromones, theophylline, and leukotriene pathway modifiers. However, these various agents differ in their mechanism, extent of action on the airway inflammatory process, and degree of clinical efficacy. Inhaled corticosteroids can control symptoms in many young children with even severe persistent wheezing, but data on their long-term safety when administered in preschool-age children are scarce. There is some information on the uninterrupted use of inhaled corticosteroids in school-age children and the absence of an adverse effect on ultimate adult height. Despite laboratory evidence of adrenal suppression in some studies, few pediatric cases of clinical adrenal insufficiency have been reported. Low-dose inhaled corticosteroid (<400 mcg/day for beclomethasone), which is adequate for controlling mild persistent symptoms, is generally safe. Chromones have a remarkable safety profile, but they are most effective for symptoms of mild severity. Promising data have been published on the efficacy and safety of leukotriene pathway modifiers when used in young children with persistent symptoms. It is uncertain whether early introduction and long-term administration of inhaled corticosteroids prevent development of irreversible airway obstruction. Nevertheless, they may be especially useful for patients with moderate to severe disease in whom other agents (chromones or leukotriene pathway modifiers) will most likely fail to control symptoms. Pediatr Pulmonol. 2003; 35:241-252.

Survey of adrenal crisis associated with inhaled corticosteroids in the United Kingdom

BACKGROUND

Until recently, only two cases of acute adrenal crisis associated with inhaled corticosteroids (ICS) had been reported worldwide. We identified four additional cases and sought to survey the frequency of this side effect in the United Kingdom.

METHODS

Questionnaires were sent to all consultant paediatricians and adult endocrinologists registered in a UK medical directory, asking whether they had encountered asthmatic patients with acute adrenal crisis associated with ICS. Those responding positively completed a more detailed questionnaire. Diagnosis was confirmed by symptoms/signs and abnormal hypothalamic-pituitary-adrenal axis function test results.

RESULTS

From an initial 2912 questionnaires, 33 patients met the diagnostic criteria (28 children, five adults). Twenty-three children had acute hypoglycaemia (13 with decreased levels of consciousness or coma; nine with coma and convulsions; one with coma, convulsions and death); five had insidious onset of symptoms. Four adults had insidious onset of symptoms; one had hypoglycaemia and convulsions. Of the 33 patients treated with 500-2000 micro g/day ICS, 30 (91%) had received fluticasone, one (3%) fluticasone and budesonide, and two (6%) beclomethasone.

CONCLUSIONS

The frequency of acute adrenal crisis was greater than expected as the majority of these patients were treated with ICS doses supported by British Guidelines on Asthma Management. Despite being the least prescribed and most recently introduced ICS, fluticasone was associated with 94% of the cases. We therefore advise that the licensed dosage of fluticasone for children, 400 micro g/day, should not be exceeded unless the patient is being supervised by a physician with experience in problematic asthma. We would also emphasise that until adrenal function has been assessed patients receiving high dose ICS should not have this therapy abruptly terminated as this could precipitate adrenal crisis.

Impaired recovery of hypothalamic-pituitary-adrenal axis function and hypoglycemic seizures after high-dose inhaled corticosteroid therapy in a toddler

BACKGROUND

Corticosteroids are the treatment of choice for children with persistent reactive airway disease. In these patients, taper and discontinuation of systemic therapy is often facilitated by transition to high-dose inhaled corticosteroid treatment.

OBJECTIVE

To report a case of impaired hypothalamic-pituitary-adrenal (HPA) axis recovery and adrenal crisis associated with prolonged high-dose inhaled therapy after long-term systemic corticosteroid treatment.

METHODS

A 32-month-old child with severe airway obstruction and wheezing was treated with long-term daily systemic (intravenous and oral) corticosteroids followed by high-dose inhaled fluticasone (440 to 1,320 microg/day). This child presented in adrenal crisis, as evidenced by severe hypoglycemia and seizures, I day after receiving the influenza vaccine. After hydrocortisone replacement and a long taper of fluticasone, the child's adrenal function returned to normal.

RESULTS

At the time of seizure, the serum glucose was 1 mg/dL. An electroencephalogram, computed tomographic scan, and magnetic resonance imaging of the brain were normal. Adrenal insufficiency was documented (morning serum cortisol, 0.6 microg/dL; after adrenocorticotrophic hormone stimulation, 8.4 microg/dL). Repeat evaluation 3 weeks after discontinuation of all corticosteroid therapy demonstrated normal HPA axis function.

CONCLUSIONS

After treatment with long-term systemic steroids, high-dose inhaled corticosteroid therapy can impair recovery of the HPA axis and place patients at risk for adrenal crisis.

Decreased morning serum cortisol levels in children with asthma treated with inhaled fluticasone propionate

OBJECTIVE

In an observational long-term study, we followed 62 children (37 males, 25 females; mean age: 11.6 +/- 2.9 years) with moderate-to-severe asthma for 2 years and studied the effects of fluticasone propionate (176-1320 microg/day) on the function of the hypothalamic-pituitary-adrenal axis.

STUDY DESIGN

Morning cortisol levels were monitored after patients had been on fluticasone for a mean of 8.0 +/- 5.2 months. Patients who had abnormal low morning cortisol levels (<5.5 microg/dL) were then switched either to lower fluticasone dosage or to other inhaled steroid formulation. Exact methods based on the binomial distribution were used to construct a 95% confidence interval for the true proportion of abnormal readings among those treated, and the Wilcoxon signed rank test was used to test for a significant difference between cortisol levels taken before and after the switch.

RESULTS

Twenty-two patients (36%) had abnormal morning cortisol levels while on fluticasone. Of the patients on a low dose (176 microg/day), 17% had abnormal values, whereas 43% of patients on a high dose (> or =880 microg/day) were abnormal. Patients with abnormal results (17/22) had their morning cortisol levels repeated 3 months after the switch. Thirteen of these patients (77%) had normal levels. A stratified analysis of the difference in morning cortisol levels before and after the switch showed significant increase in morning cortisol levels in the group receiving 440 microg/day or less of fluticasone (median difference: 5.25; confidence interval: 3.60-8.15), as well as in the group receiving 440 microg/day or more (median difference: 3.85; confidence interval: 1.00-7.60).

CONCLUSION

Inhaled fluticasone, even at conventional doses, may have greater effects on the adrenal function than previously recognized, but the clinical significance of this suppression still remains to be established.

Safety of inhaled and intranasal corticosteroids: lessons for the new millennium

Although inhaled and intranasal corticosteroids are first-line therapy for asthma and allergic rhinitis, there has recently been an increasing awareness of their propensity to produce systemic adverse effects. The availability of more potent and lipophilic corticosteroids and new chlorofluorocarbon (CFC)-free formulations has focused attention on these safety issues. The main determinant of systemic bioavailability of these drugs is direct absorption from the lung or nose, where there is no first-pass inactivation. Consequently, the systemic bioavailability of inhaled corticosteroids is greatly influenced by the efficiency of the inhaler device. Thus, when comparing different inhaled corticosteroids it is imperative to consider the unique drug/device interaction. The pharmacokinetic profile is important in determining the systemic bioactivity of inhaled and intranasal corticosteroids. For highly lipophilic drugs, such as fluticasone propionate or mometasone furoate, there is preferential partitioning into the systemic tissue compartment, and consequently a large volume of distribution at steady state. In contrast, drugs with lower lipophilicity, such as triamcinolone acetonide or budesonide, have a smaller volume of distribution. The systemic tissue compartment may act as a slow release reservoir, resulting in a long elimination half-life for the lipophilic drugs. For intranasal corticosteroids, a high degree of lipophilicity diminishes water solubility in mucosa and therefore increases the amount of drug swept away by mucociliary clearance before it can gain access to tissue receptor sites. This may reduce the anti-inflammatory efficacy in the nose, but might also reduce the propensity for direct systemic absorption from the nasal cavity. The hydrofluoroalkane (HFA) formulations of beclomethasone dipropionate are solutions and exhibit a much higher respirable fine particle dose than do the CFC formulations. Dose-response studies with one of the HFA formulations have shown therapeutic equivalence at half the dosage, with little evidence of adrenal suppression at dosages up to 800 microg/day. A lack of similar studies for another of the available HFA formulations has led to a discrepancy in the recommendations for equivalence. Although in vitro studies have pointed to a similar fine particle distribution for the HFA and CFC formulations of fluticasone propionate, this is not supported by in vivo data for lung bioavailability, suggesting that care will be required when switching these formulations. Prescribers of inhaled and intranasal corticosteroids should be aware of the potential for long term systemic effects. The safest way to use these drugs is to 'step-down' to achieve the lowest possible effective maintenance dosage.

Short-term dose-response relationships for the relative systemic effects of oral prednisolone and inhaled fluticasone in asthmatic adults

AIMS

To determine the systemic dose-response relationships with oral prednisolone and inhaled fluticasone propionate administered in a putative 11:1 mg equivalent basis, in terms of effects on adrenal, bone and haematological markers.

METHODS

Twelve asthmatic patients mean (s.e.) age, 28.8 [3.3] years, FEV1 94.7 [3.6]% predicted, FEF(25-75) 65.5 [6.1]% predicted were studied in a double-blind, double dummy randomised crossover design comparing placebo, inhaled fluticasone propionate via volumatic spacer given twice a day (ex actuator dose 0.44 mg day-1, 0.88 mg day-1, 1.76 mg day-1 ) and oral prednisolone given once daily (5 mg day-1, 10 mg day-1, 20 mg day-1 ). All treatments were for 4 days at each dose level with a 7-day washout at crossover. Measurements were made at 08.00 h after the last dose of each dose level for plasma cortisol, serum osteocalcin and blood eosinophil count.

RESULTS

There were significant dose-related effects for suppression of all three endpoints with both prednisolone and fluticasone propionate. Parallel slope analysis revealed a calculated dose ratio for relative potency of 8. 5:1 mg (95% CI 5.7-11.2) comparing Pred with FP for morning cortisol. The magnitude of suppression with FP was less for osteocalcin and eosinophils than for cortisol.

CONCLUSIONS

Systemic tissues exhibit different dose-response relationships for the effects of inhaled and oral corticosteroids with suppression of cortisol being greater than osteocalcin or eosinophils. For cortisol suppression we observed an 8.5:1 mg relative potency ratio comparing prednisolone with fluticasone propionate. Patients taking high dose inhaled fluticasone propionate should therefore be screened for evidence of impaired adrenal reserve.