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.