NCX 6560, a nitric oxide-releasing derivative of atorvastatin, inhibits cholesterol biosynthesis and shows anti-inflammatory and anti-thrombotic properties

We compared the lipid-lowering, vasodilating, anti-thrombotic and anti-inflammatory properties of NCX 6560, a novel NO-releasing derivative of atorvastatin, with those of atorvastatin. NCX 6560 and atorvastatin induced similar inhibition of Cholesterol biosynthesis in rat smooth muscle cells (IC(50)=1.9+/-0.4 and 3.9+/-1.0 microM, respectively). However, in hyperlipidemic mice, a 5-week oral treatment with NCX 6560 (46.8 mg/kg/day, p.o.) was more effective than equivalent atorvastatin (40 mg/kg/day, p.o.) at lowering serum Cholesterol (NCX 6560: -21% vs controls, P<0.05; atorvastatin: -14% vs control, P=NS). In norepinephrine-precontracted rabbit aortic rings, NCX 6560-induced vasodilation (EC(50)=53.5+/-8.3 microM) and in PC12 cells it stimulated cGMP formation (EC(50)=1.8+/-0.7 microM), while atorvastatin was inactive. In lipopolysaccharide from Escherichia coli (LPS)-treated RAW 264.7 macrophages, NCX 6560 reduced iNOS expression and dimer assembly more efficiently than atorvastatin and inhibited nitrite accumulation (IC(50)=6.7+/-1.6 microM) and TNFalpha release. U46619- or collagen plus epinephrine-induced platelet pulmonary thromboembolism in mice was reduced by NCX 6560 at 46.8 mg/kg p.o. (mortality: -44% and -56% vs vehicle, respectively; P<0.05), but not by atorvastatin 40 mg/kg, p.o. In the U46619-induced mortality model, isosorbide mononitrate (ISMN) (20 mg/kg, p.o.), a pure NO-donor, was also active (mortality: -40%, P<0.05). NCX 6560 significantly reduced ex vivo platelet adhesion to collagen at high shear (-31+/-1.3% vs vehicle), and so did ISMN (-33.3+/-1.7% vs vehicle). Atorvastatin was ineffective. NCX 6560, but not atorvastatin, reduced blood pressure in eNOS knockout mice (-16%, P<0.001 vs vehicle), an effect not observed in wild type mice. On the contrary, ISMN provoked a significant drop of blood pressure both in wild type (-20%, P<0.05 vs vehicle) and in eNOS-/- mice (-21%, P<0.05 vs vehicle). In conclusion, NCX 6560 exerts greater lipid-lowering, anti-thrombotic and anti-inflammatory effects than atorvastatin, due to a large extent to NO release.