Ranolazine: new approach for the treatment of stable angina pectoris

Formulation and Coating of Alginate and Alginate-Hydroxypropylcellulose Pellets Containing Ranolazine

The formulation and the coating composition of biopolymeric pellets containing ranolazine were studied to improve their technological and biopharmaceutical properties. Eudragit L100 (EU L100) and Eudragit L30 D-55-coated alginate and alginate-hydroxypropylcellulose (HPC) pellets were prepared by ionotropic gelation using 3 concentrations of HPC (0.50%, 0.65%, and 1.00% wt/wt) and applying different percentages (5%, 10%, 20%, and 30% wt/wt) of coating material. The uncoated pellets were regular in shape and had mean diameter between 1490 and 1570 μm. The rate and the entity of the swelling process were affected by the polymeric composition: increasing the HPC concentration, the structure of the pellets became more compact and slowed down the penetration of fluids. Coated alginate-HPC formulations were able to control the drug release at neutral pH: a higher quantity of HPC in the system determined a slower release of the drug. The nature of the coating polymer and the coating level applied affected the drug release in acidic environment: EU L100 gave better performance than Eudragit L30 D-55 and the best coating level was 20%. The pellets containing 0.65% of HPC and coated with 20% EU L100 represented the best formulation, able to limit the drug release in acidic environment and to control it at pH 6.8.

Advances in targeting voltage-gated sodium channels with small molecules

Blockade of voltage-gated sodium channels (VGSCs) has been used successfully in the clinic to enable control of pathological firing patterns that occur in conditions as diverse as chronic pain, epilepsy, and arrhythmias. Herein we review the state of the art in marketed sodium channel inhibitors, including a brief compendium of their binding sites and of the cellular and molecular biology of sodium channels. Despite the preferential action of this drug class toward over-excited cells, which significantly limits potential undesired side effects on other cells, the need to develop a second generation of sodium channel inhibitors to overcome their critical clinical shortcomings is apparent. Current approaches in drug discovery to deliver novel and truly innovative sodium channel inhibitors is next presented by surveying the most recent medicinal chemistry breakthroughs in the field of small molecules and developments in automated patch-clamp platforms. Various strategies aimed at identifying small molecules that target either particular isoforms of sodium channels involved in specific diseases or anomalous sodium channel currents, irrespective of the isoform by which they have been generated, are critically discussed and revised.

Preparation and Evaluation of Mixture of Eudragit and Ethylcellulose Microparticles Loaded with Ranolazine for Controlled Release

To minimize the unwanted toxic effects of anti-anginal ranolazine by kinetic control of drug release, it was entrapped into gastro-resistant, biodegradable eudragit (EU) and ethyl cellulose (EC) binary blend using phase separation method. Ten formulations were prepared using different polymer blend ratios and solvent. The prepared microparticles were characterized for micromeritic properties, polymer drug compatibility by Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scannibg Calorimetry (DSC), and surface morphology by Scanning Electron Micrography (SEM). The yield of microparticles was up to 90% and more than 98% of the isolated microparticles are having volume mean diameter of 285 μm. The obtained angle of repose, percentage Carr's index and tapped density values were within the limits indicating good flow properties. The surface morphology revealed that particles were free-flowing, spherical, with minute pores and invert dents on the surface. The prepared microparticles were evaluated for percentage yield, encapsulation efficiency and in vitro release studies. FT-IR and DSC studies showed no chemical interaction between the drug and used polymers The in vitro drug release studies were carried out using pH 1.2 acid buffer and pH 7.4 phosphate buffer. EU acts as an excellent pH-dependent binder and helps to release the drug in the intestine. The drug release kinetics followed different transport mechanisms. Increasing the weight fractions of EU and decreased EC helps to control the drug release from the particles. From the differential (f₁) and similarity factor (f₂), Formulation F5 was the formulation most similar to the commercially available oral formulation as reference standard. The drug release performance was greatly affected by the materials used in microparticle preparations, which allow absorption in the intestinal tract.

Ranolazine reduces Ca2+ overload and oxidative stress and improves mitochondrial integrity to protect against ischemia reperfusion injury in isolated hearts

Ranolazine is a clinically approved drug for treating cardiac ventricular dysrhythmias and angina. Its mechanism(s) of protection is not clearly understood but evidence points to blocking the late Na+ current that arises during ischemia, blocking mitochondrial complex I activity, or modulating mitochondrial metabolism. Here we tested the effect of ranolazine treatment before ischemia at the mitochondrial level in intact isolated hearts and in mitochondria isolated from hearts at different times of reperfusion. Left ventricular (LV) pressure (LVP), coronary flow (CF), and O2 metabolism were measured in guinea pig isolated hearts perfused with Krebs-Ringer's solution; mitochondrial (m) superoxide (O2·-), Ca2+, NADH/FAD (redox state), and cytosolic (c) Ca2+ were assessed on-line in the LV free wall by fluorescence spectrophotometry. Ranolazine (5 μM), infused for 1 min just before 30 min of global ischemia, itself did not change O2·-, cCa2+, mCa2+ or redox state. During late ischemia and reperfusion (IR) O2·- emission and m[Ca2+] increased less in the ranolazine group vs. the control group. Ranolazine decreased c[Ca2+] only during ischemia while NADH and FAD were not different during IR in the ranolazine vs. control groups. Throughout reperfusion LVP and CF were higher, and ventricular fibrillation was less frequent. Infarct size was smaller in the ranolazine group than in the control group. Mitochondria isolated from ranolazine-treated hearts had mild resistance to permeability transition pore (mPTP) opening and less cytochrome c release than control hearts. Ranolazine may provide functional protection of the heart during IR injury by reducing cCa2+ and mCa2+ loading secondary to its effect to block the late Na+ current. Subsequently it indirectly reduces O2·- emission, preserves bioenergetics, delays mPTP opening, and restricts loss of cytochrome c, thereby reducing necrosis and apoptosis.

Functional coupling of angiotensin II type 1 receptor with insulin resistance of energy substrate uptakes in immortalized cardiomyocytes (HL-1 cells)

BACKGROUND AND PURPOSE

Increased angiotensin II levels and insulin resistance coexist at the early stages of cardiomyopathies. To determine whether angiotensin II increases insulin resistance in cardiomyocytes, we studied the effect of angiotensin II on basal and insulin-stimulated transport rate of energy substrates in immortalized cardiomyocytes (HL-1 cells).

EXPERIMENTAL APPROACH

Glucose and palmitic acid uptakes were measured using [(3)H]2-deoxy-D-glucose and [(14)C]palmitic acid, respectively, in cells exposed or not exposed to angiotensin II (100 nM), angiotensin II plus irbesartan or PD123319, type 1 and 2 receptor antagonists, or PD98059, an inhibitor of ERK1/2 activation. Cell viability, DNA, protein synthesis and surface area were evaluated by the MTT test, [(3)H]thymydine, [(3)H]leucine and morphometric analysis, respectively. Type 1 receptor levels were measured by western blot analysis.

KEY RESULTS

Basal uptakes of glucose and palmitic acid by HL-1 cells (0.37+/-0.07 and 7.31+/-0.22 pmol per 10(4)cells per min, respectively) were both stimulated by 100 nM insulin (+91 and +64%, respectively). Cells exposed to angiotensin II remained viable and did not show signs of hypertrophy. In these conditions, the basal palmitic acid uptake of the cells increased (11.41+/-0.46 pmol per 10(4) cells per min) and insulin failed to stimulate the uptake of glucose and fatty acids. Changes in the rate of uptake of energy substrates were prevented or significantly reduced by irbesartan or PD98059.

CONCLUSIONS AND IMPLICATIONS

Angiotensin II is a candidate for increasing insulin resistance in cardiomyocytes. Our results suggest a further mechanism for the cardiovascular protection offered by the angiotensin II type 1 receptor blockers.

CVT-4325 Inhibits Myocardial Fatty Acid Uptake and Improves Left Ventricular Systolic Function without Increasing Myocardial Oxygen Consumption in Dogs with Chronic Heart Failure

BACKGROUND

Inhibition of myocardial fatty acid oxidation has been suggested as a therapeutic approach for improving cardiac function in chronic heart failure (HF). The novel piperazine derivative CVT-4325 was shown to inhibit fatty acid oxidation in cardiac mitochondria and in isolated perfused rat hearts. In the present study, we tested the hemodynamic and metabolic effects of acute intravenous CVT-4325 in dogs with HF.

METHODS AND RESULTS

HF (LV ejection fraction <or=35%) was created in eight dogs by multiple sequential intracoronary microembolizations. Treatment with CVT-4325 administered intravenously as 0.5 mg/kg bolus followed by a continuous infusion of 0.8 mg/kg/h for 40 min reduced free fatty acid (FFA) uptake (4.51+/-0.96 to 1.65+/-0.32 micromols/min, p<0.04), coronary blood flow (56+/-3 to 46+/-4 ml/min, p<0.01), and myocardial oxygen consumption (MVO2) (240+/-23 to 172+/-7 micromols/min, p<0.03), and increased LV ejection fraction (30+/-2 to 37+/-1%, p<0.0001). In the same study, but on a different day, the same dogs were treated with an inactive analogue of CVT-4325 (CVT-2540), and no hemodynamic or metabolic effects were observed.

CONCLUSIONS

In dogs with HF, acute intravenous infusion of CVT-4325 reduces FFA uptake and improves LV systolic function without increasing MVO2. The improvement in LV systolic function in the absence of an increase in MVO2 and a lower FFA uptake is consistent with the concept that inhibition of myocardial fatty acid oxidation may be an effective treatment for HF.

Metabolic modulation of myocardial ischemia

The metabolic pathways of the heart during normoxia and ischemia have been well studied. High plasma fatty acid concentrations and the myocardial accumulation of long-chain fatty acyl metabolites during ischemia correlate with increased morbidity and mortality. However, enhanced glucose use can maintain cell homeostasis, diminish ischemic injury, and be clinically beneficial. Metabolic modulators represent a new class of drugs with the potential to treat myocardial ischemia. They are ideal as adjunctive anti-ischemic therapy because they lack the hemodynamic consequences of traditional therapy and treat the underlying metabolic dysfunction that leads to contractile failure and arrhythmias. Clinical studies have demonstrated their efficacy in acute and chronic settings. It is anticipated that there will be greater utilization of this new class of agents in the near future.