The aminopyrine breath test (APBT) was used to study patients with chronic congestive heart failure before and after treatment with two chemically similar inotropic agents, amrinone (AR) and milrinone (MR), to determine their effects on hepatic microsomal function. Liver chemistries and cardiac indices were measured and correlated with the 2-hour APBT score in 11 patients with chronic congestive heart failure (5 treated with AR, 6 with MR) and five healthy control subjects. Despite normal or near-normal liver chemistries, patients with chronic congestive heart failure demonstrated overall depressed hepatic microsomal oxidative function. Patients with severe congestive heart failure had a lower mean pretreatment APBT score (AR = 3.05 ± 1.02, MR = 5.38 ± 3.09) when compared with healthy controls (10.02 ± 1.02). However, the APBT score for each individual could not be predicted from the cardiac index. Although the mean cardiac index increased significantly in both the AR and the MR treated patients by 26.14% ± 15.28 (p < 0.01) and 40.0% ± 42.27 (p < 0.025), respectively, compared with pretreatment values, the mean APBT score fell by 62.02% ± 22.5 (p < 0.005) in the former and increased by 38.35% ± 25.69 (p < 0.01) in the patients receiving MR. This discordance between the effects of AR and MR suggests possible differences in the effects of the two drugs on hepatic microsomal function.
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