Ranolazine injection into coronary or femoral arteries exerts marked, transient regional vasodilation without systemic hypotension in an intact porcine model.

BACKGROUND

We examined whether intracoronary or intrafemoral administration of ranolazine produces local vasodilation.

METHODS AND RESULTS

Effects of intra-arterial ranolazine on coronary and femoral artery vasodilation and systemic hemodynamic function were studied in anesthetized pigs (n=27). Ranolazine, nitroglycerin, or saline (control) was injected into the left anterior descending (LAD) coronary artery or femoral artery (2-mL bolus in 10 seconds). Pretreatment with prazosin (300 μg/kg IV) allowed determination of α(1)-adrenergic receptor involvement (n=8). Rapid intracoronary administration of ranolazine (0.048 mg/kg) to achieve high local concentrations resulted in 91±11% increase in LAD coronary artery flow and 39±7% reduction in coronary vascular resistance (both, P<0.0001). This effect lasted 2-3 minutes without change in heart rate or rate-pressure product. Mean arterial pressure decreased marginally (by 2±1 mm Hg, P=0.01). Maximum systemic plasma concentration (0.93±0.29 μmol/L) remained in subtherapeutic range. Pretreatment with prazosin abolished these effects. Intracoronary nitroglycerin (100 μg) increased LAD coronary artery flow by 112±25% (P=0.02), but the effect lasted <2 minutes; mean arterial pressure decreased by 4±1 mm Hg (P=0.01). Intrafemoral injection of ranolazine (0.24 mg/kg, ie, one-tenth of the systemic bolus) resulted in a 70±19% increase in femoral artery flow (P=0.05) and 26±5% reduction in femoral artery resistance (P=0.004). At 2 minutes after the injection, the femoral flow remained 16±9% above the baseline and dilatory effects occurred without tolerance to repeated injections.

CONCLUSIONS

Intracoronary or intrafemoral ranolazine bolus exerts a marked, 2- to 3-minute dilatory effect that is comparable to nitroglycerin in magnitude but more persistent, attributable primarily to α(1)-adrenergic blockade.