title: Adenosine, lidocaine, and Mg2+ (ALM): From cardiac surgery to combat casualty care--Teaching old drugs new tricks.
abstract: New frontline drugs and therapies are urgently required to protect the body from primary and secondary injuries. We review more than 10 years of work on adenosine, lidocaine, and magnesium (ALM) and its possible significance to civilian and military medicine. Adenosine is an endogenous nucleoside involved in nucleotide production, adenosine triphosphate turnover, and restoration of supply and demand imbalances. Lidocaine is a local anesthetic and Class 1B antiarrhythmic, and magnesium is essential for ionic regulation and cellular bioenergetics. Individually, each plays important roles in metabolism, immunomodulation, inflammation, and coagulation. The original idea to combine all three was as a "polarizing" cardioplegia, an idea borrowed from natural hibernators. Two recent prospective, randomized human trials have demonstrated its safety and superiority in myocardial protection over high-potassium "depolarizing" solutions. The next idea came from witnessing how the human heart spontaneously reanimated after complex operations with little inotropic support. At high doses, ALM arrests the heart, and at lower doses, it resuscitates the heart. In rat and pig models, we have shown that ALM intravenous bolus and infusion "drip" protects against acute regional myocardial ischemia, lethal arrhythmias, cardiac arrest, compressible and noncompressible blood loss and shock, endotoxemia, and sepsis. Individually, adenosine, lidocaine, or magnesium fails to protect. Protection is afforded in part by reducing inflammation, correcting coagulopathy, and lowering energy demand. We propose a unifying hypothesis involving improved central, cardiovascular and endothelium coupling to maintain sufficient tissue oxygenation and reduce primary and secondary "hit" complications. As with any new drug innovation, translation into humans is challenging.
authors.affiliation: From the Heart, Trauma and Sepsis Research Laboratory, Australian Institute of Tropical Health and Medicine, College of Medicine and Dentistry, James Cook University, Queensland, Australia.
authors.forename: Geoffrey Phillip
authors.initials: GP
authors.lastname: Dobson
authors.forename: Hayley Louise
authors.initials: HL
authors.lastname: Letson
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D006348:Cardiac Surgical Procedures; D006801:Humans; D008012:Lidocaine / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D008887:Military Medicine
chemical_list: D008012:Lidocaine; D008274:Magnesium; D000241:Adenosine