Phosphodiesterase Inhibitors and Other Agents

Amrinone and Milrinone are prototypes of type III PDE inhibitors. They decrease the breakdown of cyclic AMP in the myocardium and increase cyclic guanidine monophosphate (cyclic GMP) in vascular smooth muscle, resulting in an increase in myocardial contractility as well as arterial and venous vasodilatation.

Dosage: Milrinone 25-75 microgram/kg bolus over 10 minutes followed by a continuous infusion of 0.375-0.75 microgram/kg. Amrinone is not used because of its propensity to cause Thrombocytopenia.

Side effects: Thrombocytopenia.