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Pharmacotherapeutic group: Glucocorticoids. ATC code: R03BA02.
Pharmacology: Pharmacodynamics: Budesonide is a non-halogenated corticosteroid. It has local anti-inflammatory effects on respiratory mucosa when administered topically.
Improvement in asthma control following inhalation of budesonide can occur within 24 hours of commencing the treatment although maximum benefit is achieved after a few weeks of continuous treatment.
The precise mechanism of corticosteroid actions on inflammation in asthma is not known. Budesonide has been shown to have a wide range of inhibitory effects against several cell types (e.g., eosinophils, macrophages, mast cells, lymphocytes and neutrophils) and mediators (e.g., cytokines, leukotrienes, eicosanoids and histamine) involved in allergic and non-allergic respiratory inflammation. These actions of corticosteroids may contribute to their efficacy in asthma.
Pharmacokinetics: The activity of GIONA EASYHALER is due to the parent active substance, budesonide, which is provided as a mixture of two epimers (22R and 22S). In glucocorticoid receptor affinity studies, the 22R form is twice as active as the 22S epimer. These two forms of budesonide do not interconvert. The terminal half-life is the same for both epimers (2-3 hours). In asthmatic patients, approximately 15-25% of the inhaled budesonide dose from EASYHALER reaches the lungs. The largest fraction of the inhaled dose is retained in the oropharynx and swallowed if not rinsed out.
Absorption: After oral administration of budesonide, peak plasma concentration is achieved in about 1-2 hours and the absolute systemic availability is 6-13%. In plasma, 85-95% of budesonide is bound to proteins. In contrast, peak plasma concentration is reached approximately 30 minutes after inhalation. Most of budesonide delivered to the lungs is systemically absorbed.
Metabolism: Budesonide is mainly eliminated by metabolism. Budesonide is rapidly and extensively metabolised in liver via cytochrome P450 3A4 to two major metabolites. The in vitro glucocorticoid activity of these metabolites is less than 1% of that of the parent compound. Negligible metabolic inactivation has been observed in human lung and serum preparations.
Excretion: Budesonide is excreted in urine and faeces in the form of conjugated and non-conjugated metabolites.
Special patient populations: The exposure to budesonide may be increased in patients with liver disease. In children, the elimination half-life from plasma is markedly lower than in adults.
