Potentiation of blood antiasthmatic xanthine levels by tranquilizers in mice

Abstract

This study investigated in mice the interactions between drug, commonly used in chronic, multiple drug therapy in asthma. Pretreatment for three days with phenobarbital before injecting theophylline decreases blood xanthine levels. However, the phenothiazine derivatives, promazine or chlorpromazine when concurrently injected intraperitoneally with the xanthine derivatives, theophylline or aminophylline, elevated blood xanthine levels. These results suggest that certain phenothiazines may be of value in acute antiasthmatic therapy because they increase blood xanthine levels as well as being CNS depressants.Furthermore, phenothiazines in combination with aminophylline or theophylline in acute administration have the added advantage of markedly potentiating the increase in plasma cyclic AMP reflecting higher blood theophylline levels. It has been suggested that increased cyclic AMP may prevent the release of bronchoconstrictor substances by ensuring hte integrity of mast cells.