ADRENAL SUPPRESSION BY AEROSOL STEROID INHALATION

Nebulisation of dexamethasone sodium phosphate for the treatment of severe asthmatic horses

BACKGROUND

Inhaled corticosteroids are effective in the treatment of equine asthma. A recent study reported that nebulisation of injectable dexamethasone had low systemic bioavailability in healthy horses and could represent a cost-effective therapy for equine inflammatory lung diseases.

OBJECTIVES

To determine the effects of dexamethasone nebulisation on lung function in severe asthmatic horses. It was hypothesised that dexamethasone administered by nebulisation would be more effective than the same dose administered orally.

STUDY DESIGN

Randomised blinded experimental study in severe asthmatic horses.

METHODS

Twelve severe asthmatic horses in clinical exacerbation were randomly assigned to treatment with 5 mg of dexamethasone sodium phosphate by nebulisation (n = 6) or by oral administration (n = 6), once daily for 7 days. Lung function was evaluated at baseline, after four treatment days (D4) and 24 h after the last dose (D8). The presence of residual bronchospasm was assessed on D8 with N-butylscopolammonium bromide administration (0.3 mg/kg i.v.). A respiratory clinical score was performed daily. Serum cortisol concentration was measured at baseline, D4 and D8.

RESULTS

The pulmonary elastance was unchanged in both groups while pulmonary resistance was significantly improved in the oral group on D8 (mean reduction in 1 cm H₂ O/L/s [CI: 0.34-1.65, P = 0.003]). All horses had residual bronchospasm at the end of the study. There was a group difference in the respiratory clinical score as it was significantly reduced in the oral group, from D5 to D8. Serum cortisol concentration decreased in all subjects.

MAIN LIMITATIONS

Low number of horses and lack of placebo group.

CONCLUSIONS

Considering the lack of improvement of lung function and the hypothalamic-pituitary-adrenal axis suppression, the results of this study do not support aerosolisation of an injectable form of dexamethasone for the treatment of severe equine asthma at the dose and with the nebuliser evaluated.

Management of complications of glucocorticoid therapy

Corticosteroids are commonly employed in the treatment of a wide variety of pulmonary disorders, including asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, sarcoidosis, and pulmonary vasculitides; as well as in the lung transplant population. Frequently, steroid-induced complications contribute significantly to morbidity and diminished quality of life, often overshadowing the impact of the underlying lung disease. This article will discuss the more commonly encountered complications of corticosteroids in the context of the method of delivery, events occurring with chronic use, and events related to withdrawal.

Beclomethasone dipropionate aerosol in the treatment of asthma in steroid-independent children

Sixty-eight steroid-independent children, whose asthma was poorly controlled by bronchodilators and other anti-asthmatic drugs, were treated for six weeks with 200 to 400 mcg per day of beclomethasone dipropionate aerosol. Symptoms of wheezing, blockage, and cough, reported by the children in a daily diary, improved in 80% of cases. Use of other anti-asthmatic medications, which the children were free to modify as they wished, decreased. Objective measurements of pulmonary function, VC, FEV1, and FEV%, evaluated by weekly spirometry, also improved in almost 80% of cases. The dosages used here had no effect on early morning plasma cortisol levels and none of the children developed signs of oral candidiasis.

Effects of inhaled beclomethasone dipropionate and alternate-day prednisone on pituitary-adrenal function in children with chronic asthma

Two corticosteroid regimens, alternate-day prednisone and inhaled beclomethasone dipropionate, have been more acceptable than daily oral corticosteroids for treatment of chronic asthma. To compare the effect of these regimens on hypothalamic-pituitary-adrenal function, 20 children with asthma were evaluated while receiving 20 to 40 mg of prednisone on alternate mornings or 400 to 800 microgram per day of inhaled beclomethasone dipropionate in divided daily doses; seven children requiring only non-corticosteroid medication served as controls. Early-morning serum cortisol concentration, urinary free-cortisol excretion and the 11-desoxycortisol response to metyrapone were decreased to a similar degree among children receiving both corticosteroid regimens in comparison with the control patients and were lowest when alternate-day prednisone and inhaled beclomethasone dipropionate were given together. Thus, inhaled beclomethasone dipropionate appears similar to alternate-day prednisone in its effect on hypothalamic-pituitary-adrenal function when used alone; the effect is additive when the two are used together.

A 12-month double-blind assessment of betamethasone valerate aerosol in the management of asthma

A double-blind trial of the topically active corticosteroid, betamethasone valerate in aerosol form, in the control of chronic asthma is reported. The results show that this is an extremely effective therapeutic agent in non-steroid dependent but nonetheless moderately severe asthmatics. Patients were well controlled on 800 mug of betamethasone valerate daily and control was maintained over a 12-month period. This form of treatment has few undersirable side effects but there is probably an increased incidence of oropharyngeal and laryngeal candidiasis. In particular, adrenocortical suppression was not noted.

A short-term double-blind trial of aerosol triamcinolone acetonide in steroid-dependent patients with severe asthma

Twenty-five steroid-dependent severely asthmatic patients, ranging in age from 20 to 67 years, were hospitalized. Baseline laboratory and pulmonary function testing was followed by reduction of prednisone therapy to 5 mg daily and by entry into a randomized double-blind study of placebo vs active aerosol triamcinolone acetonide (300mug four times daily). In this four-week trial, aerosol triamcinolone acetonide further reversed airway obstruction and proved to be an effective substitute for large oral doses of steroids in steroid-dependent patients with severe asthma. No significant improvement occurred in the maximum midexpiratory flow or the maximum velocity of air flow after 50 percent or 75 percent of the vital capacity had been expelled. There was no significant difference in the frequency of untoward effects between the groups taking aerosol triamcinolone acetonide and its vehicle. No patient demonstrated any definite return of adrenal function.

Recovery of adrenal function after substitution of beclomethasone dipropionate for oral corticosteroids

Of 16 steroid-dependent asthmatic patients oral treatment has been discontinued in six and reduced in four after the introduction of beclomethasone dipropionate. Substitution of inhaled beclomethasone for oral steroids was unsuccessful in the remaining six patients. Serial adrenal function studies in the patients whose oral treatment was discontinued showed progressive recovery, and five out of six had a normal response to tetracosactrin stimulation after two months.

Beclomethasone dipropionate: a new steroid aerosol for the treatment of allergic asthma

Beclomethasone dipropionate was used in pressurized aerosols for the treatment of 60 cases of chronic allergic asthma for up to 15 months. Twenty-eight out of 37 cases were transferred to this treatment after being dependent on oral steroids for up to 16 years. Nineteen out of 23 other asthmatics not dependent on steroids were also completely controlled. No biochemical evidence of adrenal suppression was found. Steroid withdrawal symptoms were often a problem, suggesting absence of systemic absorption. The precise mode of action and metabolic fate of this corticosteroid are not yet known.