WHICH OF THE CARDIAC NATRIURETIC PEPTIDES IS MOST EFFECTIVE FOR THE TREATMENT OF CONGESTIVE HEART FAILURE, RENAL FAILURE AND CANCER?

SUMMARY 1 Cardiac natriuretic peptides consist of a family of six peptide hormones that are synthesised by three separate genes and then stored as three separate prohormones (i.e. 126 amino acid atrial natriuretic peptide (ANP), 108 amino acid B‐type natriuretic peptide (BNP) and 103 amino acid C‐type natriuretic peptide (CNP) prohormones). The ANP prohormone contains four peptide hormones: long‐acting natriuretic peptide (LANP), vessel dilator, kaliuretic peptide and ANP. 2 Currently, the only natriuretic peptide available commercially to treat congestive heart failure (CHF) is BNP (Nesiritide/Natrecor; SCIOS, Sunnyvale, CA, USA), which causes a small increase in the urine volume of 90 38 mL/h compared with 67 27 mL/h and no significant natriuresis, but has beneficial haemodynamic effects in acute CHF individuals. These haemodynamic effects probably contribute to the side‐effects of BNP in patients with acute CHF with a 27% incidence of hypotension and possibly to 22% worsening of renal function, defined as an increase in serum creatinine of 0.5 mg/dL, associated with a worse prognosis. A review of clinical trials suggests a twofold increased risk of death at 30 days post‐nesiritide treatment, a finding that needs further investigation. 3 The best of the natriuretic peptides for treating chronic CHF is the vessel dilator, which increases urinary flow up to 13‐fold and sodium excretion up to fourfold, without the previously mentioned side‐effects. The natriuretic and diuretic effects of vessel dilators last 6 h, which would allow them to be used on a four times per day basis in treating chronic CHF. 4 Atrial natriuretic peptide does not cause significant improvement in acute renal failure (ARF) in humans. The only natriuretic peptide that significantly improves ARF is the vessel dilator. Even when ARF has been established for 2 days before treatment in an ischaemic ARF animal model, vessel dilator decreases serum creatinine from 8.2 0.5 to 0.98 0.12 mg/dL in 6 days. At day 6 of ARF, mortality decreases to 14% (from 88%) without the vessel dilator. After 6 days of treatment with the vessel dilator, the proximal and distal tubules regenerate. 5 In cancer, vessel dilator, LANP, kaliuretic peptide and ANP at 1 mmol/L, decrease up to 97% of human breast, pancreatic and prostate adenocarcinoma cells, as well as small cell and squamous cell lung cancer cells within 24 h. In vivo, vessel dilator, LANP and kaliuretic peptide completely stop the growth of human panc