Relationship between amrinone plasma concentration and cardiac index

Area of Science:

• Pharmacology
• Cardiology
• Clinical Pharmacology

Background:

• Congestive heart failure (CHF) is a complex syndrome characterized by impaired cardiac function.
• Amrinone is an inotropic agent investigated for its effects on cardiac performance.

Purpose of the Study:

• To investigate the relationship between amrinone plasma concentrations and cardiac index in patients with CHF.
• To evaluate the efficacy and pharmacokinetics of amrinone administered via intravenous and oral routes.

Main Methods:

• 14 patients with CHF received intravenous amrinone (0.5-3.5 mg/kg).
• Cardiac index was measured using thermodilution; amrinone plasma levels were determined by HPLC.
• Four patients received IV infusion, and seven received oral amrinone.
• Pharmacokinetic parameters, including elimination half-life (t 1/2), were estimated.

Main Results:

• A significant correlation was found between amrinone plasma concentration and increased cardiac index (r=0.81, p<0.001) in 13/14 patients.
• Intravenous amrinone initially increased cardiac index, which declined despite constant plasma levels during infusion, then rose again.
• Oral amrinone also showed a relationship between plasma levels and cardiac index improvement (p<0.05).
• The mean elimination half-life of oral amrinone was 8.3 ± 1.1 hours.

Conclusions:

• Amrinone demonstrates a dose-dependent relationship between plasma concentration and improved cardiac index in CHF patients.
• The drug's efficacy may be influenced by complex pharmacokinetic and dynamic factors during continuous administration.
• Amrinone is a viable therapeutic option for managing congestive heart failure, with a notable elimination half-life.