Milrinone Theophylline

Positive inotropic digitalis substitutes Dobutamine, amrinone Milrinone, theophylline... 

The release of renin is altered by a wide variety of pharmacologic agents. Renin release is stimulated by vasodilators (hydralazine, minoxidil, nitroprusside), 13-adrenoceptor agonists, cx-adrenoceptor antagonists, phosphodiesterase inhibitors (eg, theophylline, milrinone, rolipram), and most diuretics and anesthetics. This stimulation can be accounted for by the control mechanisms just described. Drugs that inhibit renin release are discussed below. 

Anagrelide should not be used with other phosphodiesterase III inhibitors (e.g. milrinone) because of the potential for increased inotropic effects. Inhibitors of CYP1A2 (e.g. fluvoxamine) are predicted to increase anagrelide levels. Some caution might be required with concurrent aspirin and other platelet inhibitors. Whether anagrelide inhibits theophylline metabolism to a clinically relevant extent is not known. No pharmacokinetic interaction occurs with digoxin or warfarin. 

An experimental study into the mechanism of action of enoximone in 14 patients with ischaemic or idiopathic dilative cardiomyopathy found that pretreatment with intravenous aminophylline 7 mg/kg given over 15 minutes reduced the beneficial haemodynamic eflects of intravenous enoximone 1 mg/kg given over 15 minutes. This appears to occur because each drug competes for inhibition of cAMP specific phosphodiesterases in cardiac and vascular smooth muscle. Milrinone, another phosphodiesterase inhibitor similar to enoximone, would be expected to interact in the same way. However, there are, at present, no published reports of a possible interaction with milrinone, and no case reports of a problem occurring with the concurrent use of either drug with theophylline. The clinical importance of this study therefore awaits evaluation. 

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