Effects of theophylline on tolerance to the bronchoprotective actions of salmeterol in asthmatics in vivo

• Published in: American journal of respiratory and critical care medicine Vol. 158; no. 3; pp. 792 - 796
• Main Authors: CHEUNG, D, WEVER, A. M. J, DE GOEIJ, J. A, DE GRAAFF, C. S, STEEN, H, STERK, P. J
• Format: Journal Article
• Language: English
• Published: New York, NY American Lung Association 01.09.1998
• Subjects: Administration, Inhalation; Adrenergic beta-Agonists - administration & dosage; Adrenergic beta-Agonists - therapeutic use; Adult; Albuterol - administration & dosage; Albuterol - analogs & derivatives; Albuterol - therapeutic use; Asthma - drug therapy; Asthma - physiopathology; Biological and medical sciences; Bronchi - drug effects; Bronchial Provocation Tests; Bronchoconstriction - drug effects; Bronchodilator Agents - administration & dosage; Bronchodilator Agents - blood; Bronchodilator Agents - therapeutic use; Double-Blind Method; Down-Regulation - drug effects; Drug Interactions; Drug Tolerance; Female; Forced Expiratory Volume - drug effects; Histamine; Humans; Male; Medical sciences; Middle Aged; Pharmacology. Drug treatments; Placebos; Respiratory system; Salmeterol Xinafoate; Theophylline - administration & dosage; Theophylline - blood; Theophylline - therapeutic use; Human; Drug combination; Respiratory disease; Bronchodilator; Treatment efficiency; Oral administration; Tolerance; β2-Adrenergic receptor; β-Adrenergic receptor agonist; Asthma; Inhalation; Induced bronchoconstriction; Histamine; Chemotherapy; Treatment; Double blind study; Xanthine derivatives; Salbutamol; Obstructive pulmonary disease; Theophylline
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/ajrccm.158.3.9801036

Long-term treatment with salmeterol produces tolerance for its protective effects against bronchoconstrictor stimuli in patients with asthma. There is human in vitro evidence that theophylline may prevent beta2-adrenoceptor downregulation. Therefore, we investigated the effect of theophylline on the tolerance to the protective effect of salmeterol against histamine challenge in asthma in vivo. In a parallel 6-wk study, 25 asthmatics were treated with theophylline (mean serum level +/- SEM: 9.9 +/- 1.1 mg/L, Days 1 to 40) or placebo, combined with inhaled salmeterol (50 microgram twice daily, Days 8 to 36). Histamine challenges were carried out by tidal breathing method at entry, and at Days 4, 8, 22, 36, and 40. The response was measured by PC20. There was no significant change in PC20 after 4 d monotherapy with theophylline or placebo (mean difference +/- SEM: 0.54 +/- 0.39 and -0.02 +/- 0.41 doubling dose [DD], respectively; p > 0.15). One hour after the first dose, salmeterol afforded significant protection against histamine, as shown by an increase in PC20 in both the theophylline and placebo group (by 3.49 +/- 0.28 and 3.36 +/- 0.32 DD, respectively; p < 0. 001). However, after 2 and 4 wk salmeterol treatment, the improvements in PC20 by salmeterol were significantly reduced to 1. 80 +/- 0.35 and 1.69 +/- 0.36 DD, respectively, in the theophylline group (p < 0.001), and to 1.55 +/- 0.47 and 1.52 +/- 0.56 DD, respectively, in the placebo group (p < 0.002). These changes were not significantly different between the groups (p > 0.80). After cessation of salmeterol treatment, PC20 was not significantly different from the values at entry in either group (p > 0.90). We conclude that regular theophylline treatment neither prevents, nor worsens, the development of tolerance to the bronchoprotective effect of salmeterol in asthmatics in vivo.