What is acefylline piperazine?acefylline is a theophylline derivative which is used as a bronchodilator similarly to theophylline. it relaxes smooth muscles, relieves bronchospasm & has a stimulant effect on respiration. it stimulates the myocardium & central nervous system, decreases peripheral resistance & venous pressure & causes diuresis. the mechanism of action is still not clear, inhibition of phosphodiesterase with a resulting increase in intracellular cyclic amp does occur, but not apparently at concentrations normally used for clinical effect. other proposed mechanisms of action include adenosine receptor antagonism, prostaglandin antagonism & effects on intracellular calcium. sodium phenobarbital is a non-selective central nervous system depressant that is primarily used as sedative-hypnotic.