Long-term and short-term effects of oral prethcamide in chronic ventilatory failure.

The effect of oral prethcamide (Micoren) (a mixture of two related amides of crotonyl N' butyric acid) was compared with a placebo preparation in 13 patients with established chronic ventilatory failure. Part I of the study comprised a double-blind single cross-over trial with an initial assessment and two further assessments at the end of each period of one month. Prethcamide was taken in 200-mg. doses four times daily. No subjective or objective changes were noted, and in particular the resting Pco(2) showed no change.Part II of the study comprised a double-blind single cross-over trial of the short-term effect of prethcamide compared with placebo in 12 patients in chronic ventilatory failure. Frequent estimations of mixed venous Pco(2) were made with a rebreathing technique for four and a half hours after ingestion of prethcamide or placebo preparation.Following prethcamide a fall in Pco(2) level to a minimum value at 30 minutes of 93% of control values and persisting for about three hours was noted for the group as a whole. The fall represents a lowering by about 4 mm. Hg of the mixed venous Pco(2).It is concluded that, though in patients with chronic ventilatory failure prethcamide may reduce the Pco(2) in the short term, there is no subjective benefit or observable objective change following repeated administrations over a period of one month.