Comparison of fenoterol and orciprenaline with regard to broncho-dilating action and beta 2-selectivity

A double-blind crossover trial was performed comparing orciprenaline (10 mg) and fenoterol (5 mg) by oral administration in forty-four patients with bronchial asthma. Measurement of VC, FEV1, respiratory impedance (ZR), blood pressure and pulse rate, and observation of subjective symptoms, râles, and side-effects, were made over the 4 hours following oral administration of the drugs. FEV1 increased through the 4 hours reaching a peak at 3 hours with both drugs. The per cent increase of FEV1 was statistically significant at each measuring time for both drugs (p less than 0.01), and was significantly larger in fenoterol than in orciprenaline at 2 and 3 hours (p less than 0.05). ZR with fenoterol decreased from 2 hours to 4 hours with a significant difference from ZR with orciprenaline (p less than 0.05). Side-effects such as palpitation, finger tremor or headache were seen in 36.4% cases with fenoterol and 30.5% with orciprenaline, but the degree of the side-effects was minimal. Finger tremor was observed in one case with orciprenaline and ten cases with fenoterol. Palpitation was observed in five cases with each of the drugs. Because finger tremor seems to be due to beta 2-stimulation and palpitation seems to be due to beta 1-stimulation, fenoterol was supposed to be more beta 2-selective than orciprenaline. In conclusion fenoterol had a high beta 2-selectivity and a powerful and long-lasting broncho-dilating effect compared with orciprenaline.