Objectives: The thermogenic effect of amrinone is unknown and its util
ization in patients with severe cardiac failure could. potentially inc
rease oxygen requirements and therefore aggravate oxygen debt. Consequ
ently, the present study was undertaken to assess the thermogenic resp
onse to amrinone at three different plasma concentrations under contro
lled conditions and to analyze amrinone's effects on various biochemic
al variables. Design: A prospective, unblinded, controlled study. The
initial control period was followed by three sequential, experimental
treatments. Subjects: Ten young, healthy, male volunteers with normal
body weight. Interventions: Three experimental periods. Amrinone was a
dministered intravenously in progressive doses: a) 0.5 mg/kg followed
by 5 mu g/ kg/min; b) 0.5 mg/kg followed by 10 mu g/kg/min; and c) 1.0
mg/kg followed by 10 mu g/kg/min. Measurements and Main Results: Oxyg
en consumption (Vo(2)) and CO2 production were continuously measured b
y means of a computerized indirect calorimeter. At the highest dose, a
mrinone produced a slight and significant (p < .01) increase in Vo(2)
and in resting metabolic rate (+ 4.5% and + 3.7%, respectively), while
no change in CO2 production or in respiratory quotient occurred throu
ghout the study. At the medium and high doses, amrinone increased plas
ma free fatty acid concentrations by 38% and 53%, respectively (p < .0
5). No variation in plasma glucose, lactate, insulin, norepinephrine,
or epinephrine concentrations was observed during the study. Conclusio
ns: Amrinone administered intravenously at therapeutic doses has minim
al thermogenic and metabolic effects in humans without cardiac failure
.