Exacerbation of verapamil-induced hyperglycemia with glucagon.

To evaluate the effects of verapamil intoxication and glucagon treatment on blood glucose levels in an intact canine model, 15 mg/kg verapamil was administered intravenously over a 30-minute period to mongrel dogs under pentobarbital anesthesia. Animals in the experimental group subsequently were administered 2.5 mg glucagon followed by an infusion of 2.5 mg per hour; control group animals were administered an equal volume of saline. Blood glucose was assessed before verapamil administration (baseline), and at 10 minutes (time 10) and 60 minutes (time 60) after completion of the verapamil infusion. Glucose values were compared between control and experimental groups using Dunnett's method (P = .05). At baseline, no animals were hyperglycemic and there was no difference in glucose levels. Animals in both groups became hyperglycemic after verapamil infusion. At time 10, the experimental group had significantly higher glucose levels (265 +/- 17.1 mg/dL) than the control group (209 +/- 18.3 mg/dL). By time 60, there was no significant difference between glucose values in the control (262 +/- 31.4) and experimental (246 +/- 24.8) groups. It was concluded that verapamil intoxication consistently resulted in hyperglycemia in this model. Glucagon therapy was associated with an early but nonsustained exacerbation of verapamil-induced hyperglycemia.