GLUCAGON AND PHENYLEPHRINE COMBINATION VS GLUCAGON ALONE IN EXPERIMENTAL VERAPAMIL OVERDOSE

Objective: To evaluate glucagon and phenylephrine in combination as a treatment for the hemodynamic effects of verapamil overdose, Methods: Pentobarbital-anesthetized and instrumented dogs were overdosed using a previously developed verapamil overdose model (15 mg/kg IV over 30 m inutes), The animals were maintained and observed for 90 minutes or un til death. Cardiac output (GO), heart rate (HR), and mean arterial pre ssure (MAP) were monitored, Following the 30-minute verapamil infusion (toxicity), the control animals received no treatment; the glucagon a nimals received a 5-mg glucagon bolus and a drip of 5 mg/90 minutes; a nd the glucagon/phenylephrine animals received the same glucagon thera py plus a phenylephrine drip titrated to 180 mu g/min min over 15 minu tes. The groups were compared using analysis of variance: the experime ntal variables were group and time; the response variables were change s from toxicity for the hemodynamic parameters. Post-hoc comparisons w ere done with a set at 0.05. Results: A significant change in CO was s een in the glucagon group (Delta = 2.6 L/min) and the glucagon/phenyle phrine group (Delta = 1.9 L/min) compared with the control group (Delt a = 0.8 L/min). The change in CO was significantly larger for the gluc agon animals compared with the glucagon/phenylephrine animals. The cha nge in MAP for the glucagon/phenylephrine group (Delta = 24 mm Hg) was significant compared with the control group (Delta = 14 mm Hg). The M AP change for the glucagon group (Delta = 19 mm Hg) was not significan tly different from that of either the control or the glucagon/phenylep hrine group. The change in glucagon HR (Delta = 6 beats/min) was signi ficant compared with the control group (Delta = -4 beats/min) and the glucagon/phenylephrine group (Delta = -4 beats/min). Conclusion: The g lucagon/phenylephrine therapy improved MAP compared with the control, but reduced CO and HR compared with glucagon alone. Glucagon/phenyleph rine therapy is not as effective as glucagon in reversing the hemodyna mic effects of experimental verapamil overdose.