Biotransformation rate (in vitro) and systemic potency (in vivo) of the topical glucocorticoid budesonide in male and female rats

Human liver budesonide sulphotransferase is inhibited by testosterone and correlates with by testosterone sulphotransferase

Budesonide, a corticosteroid used in the treatment of asthma and allergic reactions, is almost entirely cleared by metabolism in man. We describe the sulphation of budesonide in human liver and lung and provide evidences that the sulphation of budesonide is catalysed by testosterone sulphotransferase. A rapid and reproducible radiometric assay for budesonide sulphotransferase is described. Liver specimens were obtained from 35 men and 65 women and lung specimens from 2 women and 17 men. The average hepatic budesonide sulphation rate was significantly higher in men (41.1 pmol.min-1.ml-1) than women (28.2 pmol.min-1.mg-1). In the lung, the mean budesonide sulphation rate was 5.0 pmol.min-1.mg-1. Testosterone strongly inhibited the hepatic sulphation of budesonide, whereas p-nitrophenol and dopamine were poor inhibitors; the IC50 was 7.0 uM (testosterone), 320 uM (p-nitrophenol) and 510 uM (dopamine). The hepatic rates of testosterone, p-nitrophenol and dopamine sulphation were measured in the same samples assayed for budesonide sulphotransferase. There was a correlation between the hepatic rates of budesonide and testosterone sulphation (P < 0.001; r = 0.810). The activity of testosterone sulphotransferase was significantly greater in men than women (22.0 vs. 17.2 pmol.min-1.mg-1), whereas those of dopamine and p-nitrophenol sulphotransferase were not sex dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of budesonide in children with asthma

The pharmacokinetics of the glucocorticoid budesonide was studied in 6 children with asthma after i.v. injection of 0.5 mg and oral inhalation of 1 mg as an aerosol. Budesonide is a 1:1 mixture of the epimers 22 S and 22 R, which were assayed separately by HPLC combined with RIA. All pharmacokinetic parameters of the epimers differed except the half-life of about 1.5 h. It was significantly shorter than that reported in adults. Plasma clearance averaged 103 l X h-1 for epimer 22 R and 74 l X h-1 for epimer 22 S; calculated per kg body weight these values were about 50% higher than in adults. The difference was about 40% when calculated per m2 of body surface area. Since budesonide is a high-clearance drug, the data indicate higher liver blood flow X kg-1 body weight and m2 of body surface area in children. The systemic availability of the aerosol was approximately 30% of nominal dose, i.e. the same as in adults. The high clearance and short half-life of budesonide in children are advantageous in reducing the risk of possible systemic side-effects of prophylactic treatment of asthma in childhood.

Budesonide. A preliminary review of its pharmacodynamic properties and therapeutic efficacy in asthma and rhinitis

Budesonide is a non-halogenated glucocorticosteroid which has been shown to possess a high ratio of topical to systemic activity compared with a number of reference corticosteroids such as beclomethasone dipropionate, flunisolide, and triamcinolone acetonide. It appears to undergo extensive first-pass metabolism to metabolites of minimal activity which accounts for the low level of systemic activity. The majority of therapeutic trials in asthma have been of short term duration and have demonstrated that conventional doses of inhaled budesonide (200 to 800 micrograms/day) and beclomethasone dipropionate (400 to 800 micrograms/day) are of similar efficacy in both adults and children with moderate to severe asthma. Other studies have compared high doses of inhaled budesonide (400 to 3200 micrograms/day in 4 divided doses) with both alternate day (7.5 to 60 mg) and daily (7.5 to 40 mg) oral prednisone in patients with severe or unstable asthma. In the small number of such trials to date, inhaled budesonide was superior to prednisone with respect to the level of asthma control and the lesser influence on adrenal function. Long term open studies have similarly shown that inhaled budesonide can be gradually substituted for oral prednisone in steroid-dependent patients, often with a concomitant improvement in pulmonary function and asthma control. Intranasal budesonide (200 to 400 micrograms/day) relieves nasal symptoms in patients with seasonal allergic, perennial allergic and vasomotor rhinitis. In comparative studies in patients with seasonal rhinitis it has been shown to be of similar efficacy as intranasal flunisolide and intranasal beclomethasone dipropionate and superior to intranasal sodium cromoglycate (cromolyn sodium) and the antihistamine dexchlorpheniramine. Following inhalation, the most commonly reported side effects have been candidiasis, dysphonia and sore throat, while after intranasal administration the most frequent adverse reactions have been nasal stinging, throat irritation, dry nose and slight nasal bleeding. At usual dosages, both formulations of budesonide appear to have little or no effect on adrenal function. Thus, at this stage in its development budesonide has been shown to offer an effective alternative to oral or other inhaled corticosteroids in the management of asthma and rhinitis. However, its relative efficacy and tolerability during long term use, compared with beclomethasone dipropionate, remains to be clarified.