Acefylline (Theophyllineacetic acid) (GMP), a xanthine derivative, is an Adenosine Receptor antagonist. Acefylline (GMP) is a peptidylarginine deiminase (PAD) activator. Acefylline (GMP) is also a bronchodilator and cardiac stimulant that inhibits rat lung cAMP phosphodiesterase isoenzymes. Acefylline (GMP) can be used in asthma research[1][2][3].