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Thorax 56:529-535 doi:10.1136/thorax.56.7.529
  • Original article

Decreased bronchodilating effect of salbutamol in relieving methacholine induced moderate to severe bronchoconstriction during high dose treatment with long acting β2 agonists

Table 3

Methacholine provocation tests and recovery time of FEV1

PC20methacholine (mg/ml ) PD30+methacholine (mg) Recovery time (min)
Formoterol (n=17) 2.23 (1.6 to 3.1)3-150 2.48 (0.38–25.6)3-150 3-159 30.6 (21 to 45)3-150
Salmeterol (n=16) 1.59 (1.1 to 2.3)3-150 1.58 (0.28–6.4)3-150 25.8 (17 to 39)3-150
Placebo (n=16) 0.81 (0.57 to 1.1) 0.74 (0.08–4.8)  6.9 (4.5 to 10)

  • Values are geometric mean (95% CI) for PC20 and recovery time, and geometric mean (range) for PD30+. Values for recovery time above 60 minutes arbitrarily set at 75 minutes.

  • PC20 = concentration of methacholine provoking a decrease in FEV1 of 20%; PD30+ = cumulative dose of methacholine provoking a decrease in FEV1 of ⩾30%.

  • ↵3-150 p<0.05 compared with placebo;

  • ↵3-159 p<0.05 compared with salmeterol.

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