Assessment of the systemic effects of inhaled glucocorticosteroids: the influence of blood sampling technique and frequency on plasma cortisol and leucocytes

Summary Twelve healthy males (mean age 27.6 y, range 23–35 y) took part in a randomized, double-blind, crossover study of the effect of blood sampling technique (separate isolated venepunctures vs use of an IV cannula) and frequency (overnight vs morning) on plasma cortisol and white blood cell count after inhalation of a single dose of budesonide 3.2 mg or placebo, in order to establish the more sensitive method for future use.Sampling technique and frequency affected neither leucocytes nor plasma or urinary cortisol. Budesonide suppressed both plasma and urine free cortisol and delayed the nocturnal rise due to the circadian rhythm, thus reducing the AUC of plasma cortisol vs time.Lymphocytes, eosinophils and monocytes were decreased and neutrophils and total white blood cells were increased by the high dose of budesonide used. Lymphocytes and neutrophils showed significant changes earlier than eosinophils and cortisol and may be the variables of choice under certain conditions.Frequent sampling gave more complete information about the systemic effect of the drug than single morning samples.