Effects of the antitussive fominoben (PB89) on hypoxia in chronic obstructive lung disease: comparison with dextromethorphan using a double-blind method.

We studied the effects of a non-narcotic, centrally acting antitussive, fominoben (PB89), on hypoxia in sixty patients suffering from chronic obstructive lung diseases (COLD), utilizing a double-blind method and using the antitussive dextromethorphan as a reference drug. By the oral administration of a dose of 2 fominoben tablets (160 mg) three times a day for 2 weeks, a significant increase in arterial O2 pressure (PaO2), a decrease in arterial CO2 pressure (PaCO2), and a rise in pH were observed. However, alveolar-arterial O2 difference (A-aDO2) was not improved. On the other hand, after administration of a dose of 2 dextromethorphan tablets (30 mg) three times a day for 2 weeks, no increase in PaO2, no decrease in PaCo2 and no improvement in A-aDO2 were observed, although a rise in pH was seen. The increase in PaO2 by fominoben was marked in COLD with dyspnoea. No improvement of A-aDO2 despite a decrease in PaCO2 suggests that fominoben might increase alveolar ventilation, in spite of its effect as an antitussive, exerting a favourable effect on hypoxia. It is, therefore, speculated that the cough centre and the respiratory centre are capable of functioning independently of each other.