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Bioavailability of Theophylline from Three Different Tablets in Asthmatic Patients and Their Bronchodilating Effects in Combination with Terbutaline Inhalation
Author(s) -
Svedmyr Karin,
Mellstrand Tore,
Svedmyr Nils
Publication year - 1982
Publication title -
allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.363
H-Index - 173
eISSN - 1398-9995
pISSN - 0105-4538
DOI - 10.1111/j.1398-9995.1982.tb01884.x
Subject(s) - theophylline , bioavailability , terbutaline , bronchodilator , medicine , inhalation , asthma , anesthesia , pharmacokinetics , pharmacology
The bioavailability of three different theophylline tablets (microcrystallinic theophylline, Theolair®, Nuelin®, 3M Riker), choline theophyllinate as a new film‐coated tablet (Teovent®, Ferrosan, Sweden) and theophyllaminopropanol (Oxyphylline® Draco, Sweden) was investigated in eight adult asthmatics in a randomized, double‐blind, cross‐over study. Effects on ventilatory capacity (FEV 1 and FVC), circulation (heart rate and blood pressure) and skeletal muscle tremor were followed. The theophylline concentration was determined by gas chromatography. Forty‐five minutes after theophylline administration the plasma concentrations were almost the same for all four formulations. The bioavailability was also almost identical. The half‐life for intravenous theophylline in these asthmatics was 7.4 ± 0.64. The three tablet formulations had equal effect on FEV 1 and the effect was sustained throughout the 6‐h period. Six hours after theophylline administration five terbutaline inhalations induced the same further increase in FEV 1 . The results indicate that theophylline alone has only a moderate acute bronchodilating effect at recommended plasma concentrations but gives a good effect when combined with inhaled β 2 ‐adrenostimulants.