Fixed combination isosorbide dinitrate–hydralazine for nitric-oxide-enhancing therapy in heart failure

Nitric oxide donor and non steroidal anti inflammatory drugs as a therapy for muscular dystrophies: evidence from a safety study with pilot efficacy measures in adult dystrophic patients

This open-label, single centre pilot study was designed to evaluate safety and tolerability of the combination of the drugs isosorbide dinitrate, a nitric oxide donor, and ibuprofen, a non steroid anti-inflammatory drug, in a cohort of adult dystrophic patients (Duchenne, Becker and Limb-Girdle Muscular Dystrophy). Seventy-one patients were recruited: 35, treated with the drug combination for 12 months, and 36 untreated. Safety and adverse events were assessed by reported signs and symptoms, physical examinations, blood tests, cardiac and respiratory function tests. Exploratory outcomes measure, such as the motor function measure scale, were also applied. Good safety and tolerability profiles of the long-term co-administration of the drugs were demonstrated. Few and transient side effects (i.e. headache and low blood pressure) were reported. Additionally, exploratory outcomes measures were feasible in all the disease population studied and evidenced a trend towards amelioration that reached statistical significance in one dimension of the MFM scale. Systemic administration of ibuprofen and isosorbide dinitrate provides an adequate safety margin for clinical studies aimed at assessing efficacy.

Hydralazine does not ameliorate nitric oxide resistance in chronic heart failure

PURPOSE

The A-HeFT trial demonstrated incremental survival with hydralazine/isosorbide dinitrate combination in African-American patients with chronic heart failure (CHF). It has been suggested that hydralazine might enhance nitric oxide (NO)-mediated effects of organic nitrates by decreasing superoxide (O (2) (-) ) formation, one of the factors inducing NO resistance. We evaluated whether hydralazine therapy potentiates nitrate-induced vasodilation and inhibition of platelet aggregation by ameliorating NO resistance.

METHODS

Patients (n = 14) with NYHA class II-III CHF were studied in a randomised, double-blind, placebo-controlled, crossover study of the effects of hydralazine therapy (25 mg b.d., for 1 week) on physiological responsiveness to glyceryl trinitrate (GTN). Vascular response to GTN was assessed via applanation tonometry, as change in augmentation index (AIx) over time. Platelet responsiveness to GTN and sodium nitroprusside (SNP) was determined, as inhibition of ADP-induced platelet aggregation. O (2) (-) release was evaluated during aggregation via lucigenin-derived chemiluminescence.

RESULTS

Platelet responsiveness to the NO donors GTN and SNP was impaired, denoting the presence of severe NO resistance. Hydralazine therapy decreased systolic blood pressure by 6.8 +/- 10.5 (S.D.) mmHg (p = 0.02), and caused a reduction in AIx by 15 +/- 24% (p = 0.03). However, there were no significant changes in platelet aggregability and associated O (2) (-) release, or in platelet or vascular responses to NO donor.

CONCLUSION

The results of the present study do not support the assumption that hydralazine could be viewed as a "NO enhancer"; there is no evidence of attenuation of NO resistance by hydralazine treatment.

Editorial commentary on fixed combination isosorbide dinitrate/hydralazine for nitric-oxide-enhancing therapy in heart failure

Systolic heart failure is a condition that exerts a devastating toll on those affected. Therefore, treatments that improve heart failure outcomes incrementally, over and above the currently best available treatments are desperately needed. The fixed-dose combination of isosorbide dintrate-hydralazine provides unambiguous, incremental clinical benefits. However, isosorbide dinitrate/hydralazine has the dubious distinction of being labeled as the first FDA-approved, ethnicity-specific drug. The hypothesis that isosorbide dinitrate/hydralazine provides incremental benefit in non-African-Americans, as proven in the African-American Heart Failure Trial (AHEFT), has not yet been formally tested. Thus, the thesis that the positive AHEFT findings apply only to African-Americans should be rejected, until compelling evidence is available to support this rather implausible notion.