Comparison of the Protective Effect Amongst Anticholinergic Drugs on Methacholine-Induced Bronchoconstriction in Asthma

Abstract

The protective effect of inhaled anticholinergic drugs in the methacholine-induced bronchospasm is well-known. The objective of this study was to assess if any possible differences may be found among Ipratropium (IB), Oxitropium (OXI) and Tiotropium (TIO) pre-treatments to obtain the protective effect. Forty-four patients with intermittent bronchial asthma and PD₂₀FEV₁ < 200 μ g were selected (24 M, 20 F; mean age 32 ± 8.8). On the baseline, they had mean FEV₁%: 98.8 ± 8.54 of theoretical and mean PD₁₅FEV₁ 111.8 ± 61.04 μ g. After 72 hours, all patients underwent a second methacholine challenge and were given Ipratropium (40 μ g by MDI in 14 pts) or Oxitropium (200 μ g by MDI in 14 pts) or Tiotropium (18 μ g by Handihaler in 16 pts) sixty minutes before the test. Sixty minutes after the bronchodilator inhalation, the FEV₁% increase was higher (p < 0.05) in OXI (6.7 ± 4.83%) and TIO groups (6.11 ± 2.54%) than in the IB group (3.8 ± 1.96%). In the IB group PD₁₅FEV₁ and PD₂₀FEV₁ were obtained in all patients, while in the OXI group they were obtained in 12 and 5 pts respectively and in the TIO group in 14 and 5 pts respectively. Normal hyperreactivity was obtained in 2 patients, in both OXI and TIO groups. In OXI and TIO, the PD₁₅ obtained after drug pre-medication, was similar (respectively 1628 ± 955.7 and 1595.5 ± 990 μ g), but higher (p < 0.0001) in comparison to the PD₁₅ measured in the IB group (532.2 ± 434.8 μ g). Also, the dose-response slope (decline percentage of FEV₁/cumulative methacholine dose) after PD₁₅ was similar in both OXI and TIO groups but different in the IB group. A significant relationship (p < 0.01) was found between PD₁₅FEV₁ (obtained in 40 pts) and the increase in FEV₁% obtained 60 minutes after bronchodilator inhalations (r = 0.53). In conclusion, with a standard dose, both Oxitropium and Tiotropium seem to have the same protective effect in bronchial asthma but higher than Ipratropium. It's probable that the best dose of Ipratropium should be a higher one than the usual dose taken.

Keywords:

• anticholinergic
• asthma
• bronchodilator
• methacholine test
• protective effect