Effects of epinephrine and ritodrine in dogs with acute hyperkalemia.
As plasma potassium concentrations, whether normal or elevated, can be reduced by intravenous administration of either epinephrine or ritodrine, the effects of these drugs were examined during acute hyperkalemia. Six anesthetized dogs were studied every 2 wk, on 18 separate occasions. Hyperkalemia was induced by intravenous infusion of potassium chloride, resulting in plasma potassium concentrations of 9.6 +/- 0.3 mEq/L (mean +/- SEM), bradycardia, and idioventricular rhythm. Dogs were then given slow intravenous injections every 30 min of either saline (controls), epinephrine, or ritodrine. Epinephrine doses were 0.01, 0.1, 1.0, 10, or 100 micrograms/kg; ritodrine doses were 0.1, 1.0, 10, 100, or 1000 micrograms/kg. At the highest does, both epinephrine and ritodrine caused clinically important decreases in plasma potassium, reducing concentrations to below 7.0 mEq/L. Ritodrine had a significantly greater effect than epinephrine. Side effects included hypertension and dysrhythmias with epinephrine, serious hypotension with ritodrine, and tachycardia with both drugs. For both drugs, the doses that caused a decrease in plasma potassium also caused an increase in heart rate and there was a correlation between plasma potassium levels and heart rate. Epinephrine and ritodrine may be useful in treating acute hyperkalemia, but cardiovascular side effects may occur. Increased heart rate could be used as an indicator of therapeutic effect and the magnitude of the increase in heart rate may be helpful in predicting the level of response.
Follett
D V
DV
Department of Surgery, School of Veterinary Medicine, University of California, Davis.
Loeb
R G
RG
Haskins
S C
SC
Patz
J D
JD
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004562:Electrocardiography; D004837:Epinephrine / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D006947:Hyperkalemia / Q000188:drug therapy*; D007262:Infusions, Intravenous; D012312:Ritodrine / Q000009:adverse effects / Q000627:therapeutic use*
D012312:Ritodrine; D004837:Epinephrine