[Originality of the mode of action of almitrine dimesylate].

Very few therapeutic measures of proven effectiveness are available for the management of chronic bronchitis with chronic respiratory failure. Long-term oxygen therapy undoubtedly improves functional and vital prognoses in patients with severe hypoxaemia (55 less than or equal to PaO2 less than or equal to 60 mmHg) or chronic post-hypoxia cor pulmonale, but its indications are limited by its cost and by numerous practical problems. Owing to its mode of action and pharmacological effects, almitrine bismesylate corrects the main physiopathological disorders underlying hypoxaemia and its complications in chronic bronchitis. Improvement in arterial and tissue oxygen supply and decrease in hypercapnia result from the specific and original action of the drug on the distribution of alveolar ventilation-perfusion ratios--an action that has been clearly demonstrated by the inert gas method and by radioisotopic techniques. Such a mode of action differentiates almitrine bismesilate from long-term oxygen therapy which has similar effects, at least qualitatively, on tissue oxygenation. The lack of undesirable effects on central nervous system, pulmonary circulation and respiratory mechanics confirms the originality and safety of a drug which unquestionably constitutes a novel and major contribution to the long-term treatment of chronic bronchitis with hypoxaemia.