ISSN:
1432-1041
Keywords:
Asthma Propranolol
;
Beta adrenoceptor Blockade
;
Bronchoconstriction
;
Histamine
;
Nonspecific airway hyperresponsiveness
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary Responsiveness to inhaled histamine and DL propranolol hydrochloride was measured in 31 adult asthmatics and compared with bronchoconstriction provoked by acute oral propranolol dosing (max 160 mg). Twelve asthmatics developed ≥ 15% reduction in the forced expired volume in 1 s (FEV1), 2 h after ≤ 100 mg oral propranolol; cardiac β-adrenoceptor blockade was confirmed by cycle exercise tests in the 19 without airway response. The provocative inhaled dose of each aerosol causing a 20% fall in FEV1 (PC20) was lower, histamine 0.43 mg·ml−1, propranolol 3.12 mg·ml−1, in the 12 with a positive oral test compared with the 19 with a negative test, PC20 histamine 1.65 mg·ml−1, PC20 propranolol 16.2 mg·ml−1 (P 〈 0.001 for both aerosols). A correlation was demonstrated between the PC20 values for asthmatics with a negative oral test (r=0.72, P 〈 0.001, n=19) but not for the remainder (r=0.14, P 〉 0.05, n=12). Plasma propranolol concentrations (CL, ng·ml−1) after the final oral dose did not correlate with the % Δ FEV1(26.3) (r=-0.28) when an airway response was provoked or with the reduction in exercise tachycardia (25.9%) (r=0.31) when no bronchoconstriction occurred. CL exceeded the limit of detection after the final inhaled propranolol dose (7.5 ng·ml−1) and was weakly related to the PC20 propranolol value (r=0.53, P=0.01, n=27). The prevalence of a positive oral challenge was low in this group (39%). APC20 propranolol value which was 100% sensitive as a predictor of a positive oral test had low specificity (58%) and a low predictive value (60%). This study has not found that nonspecific bronchial responsiveness to histamine or specific responsiveness to inhaled propranolol can be employed to predict bronchoconstriction in asthmatics following acute oral propranolol dosing.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00280933
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