Safety, tolerability, and pharmacokinetics of SR 49059, a V1a vasopressin receptor antagonist, after repeated oral administration in healthy volunteers

Arginine vasopressin receptor 1a is a therapeutic target for castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) recurs after androgen deprivation therapy (ADT) and is incurable. Reactivation of androgen receptor (AR) signaling in the low androgen environment of ADT drives CRPC. This AR activity occurs through a variety of mechanisms, including up-regulation of AR coactivators such as VAV3 and expression of constitutively active AR variants such as the clinically relevant AR-V7. AR-V7 lacks a ligand-binding domain and is linked to poor prognosis. We previously showed that VAV3 enhances AR-V7 activity to drive CRPC progression. Gene expression profiling after depletion of either VAV3 or AR-V7 in CRPC cells revealed arginine vasopressin receptor 1a (AVPR1A) as the most commonly down-regulated gene, indicating that this G protein-coupled receptor may be critical for CRPC. Analysis of publicly available human PC datasets showed that AVPR1A has a higher copy number and increased amounts of mRNA in advanced PC. Depletion of AVPR1A in CRPC cells resulted in decreased cell proliferation and reduced cyclin A. In contrast, androgen-dependent PC, AR-negative PC, or nontumorigenic prostate epithelial cells, which have undetectable AVPR1A mRNA, were minimally affected by AVPR1A depletion. Ectopic expression of AVPR1A in androgen-dependent PC cells conferred castration resistance in vitro and in vivo. Furthermore, treatment of CRPC cells with the AVPR1A ligand, arginine vasopressin (AVP), activated ERK and CREB, known promoters of PC progression. A clinically safe and selective AVPR1A antagonist, relcovaptan, prevented CRPC emergence and decreased CRPC orthotopic and bone metastatic growth in mouse models. Based on these preclinical findings, repurposing AVPR1A antagonists is a promising therapeutic approach for CRPC.

Effect of small molecule vasopressin V1a and V2 receptor antagonists on brain edema formation and secondary brain damage following traumatic brain injury in mice

The attenuation of brain edema is a major therapeutic target after traumatic brain injury (TBI). Vasopressin (AVP) is well known to play a major role in the regulation of brain water content and vasoendothelial functions and to be involved in brain edema formation. Therefore, the aim of the current study was to analyze the antiedematous efficacy of a clinically relevant, nonpeptidic AVP V1a and V2 receptor antagonists. C57Bl6 mice were subjected to controlled cortical impact (CCI) and V1a or V2 receptors were inhibited by using the highly selective antagonists SR-49059 or SR-121463A either by systemic (intraperitoneal, IP) or intracerebroventricular (ICV) application. After 24 h, brain edema, intracranial pressure (ICP), and contusion volume were assessed. Systemically applied AVP receptor antagonists could not reduce secondary lesion growth. In contrast, ICV administration of AVP V1a receptor antagonist decreased brain edema formation by 68%, diminished post-traumatic increase of ICP by 46%, and reduced secondary contusion expansion by 43% 24 h after CCI. The ICV inhibition of V2 receptors resulted in significant reduction of post-traumatic brain edema by 41% 24 h after CCI, but failed to show further influence on ICP and lesion growth. Hence, centrally applied vasopressin V1a receptor antagonists may be used to reduce brain edema formation after TBI.

Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems

The neurohypophysial hormone arginine vasopressin (AVP) is essential for a wide range of physiological functions, including water reabsorption, cardiovascular homeostasis, hormone secretion, and social behavior. These and other actions of AVP are mediated by at least three distinct receptor subtypes: V1a, V1b, and V2. Although the antidiuretic action of AVP and V2 receptor in renal distal tubules and collecting ducts is relatively well understood, recent years have seen an increasing understanding of the physiological roles of V1a and V1b receptors. The V1a receptor is originally found in the vascular smooth muscle and the V1b receptor in the anterior pituitary. Deletion of V1a or V1b receptor genes in mice revealed that the contributions of these receptors extend far beyond cardiovascular or hormone-secreting functions. Together with extensively developed pharmacological tools, genetically altered rodent models have advanced the understanding of a variety of AVP systems. Our report reviews the findings in this important field by covering a wide range of research, from the molecular physiology of V1a and V1b receptors to studies on whole animals, including gene knockout/knockdown studies.

Targeting platelets for prevention and treatment of cardiovascular disease

Platelets play an important role in the development of thrombosis, atherosclerosis, hypertension, heart attack and stroke. As a result, pharmacologic interventions that influence platelet functions, such as adhesion, aggregation and the release of different factors, are considered useful for the prevention and treatment of cardiovascular disease. Although classical anti-platelet agents have proven beneficial effects for the treatment of some specific cardiovascular diseases, there are limitations for their use as these drugs target platelet function directly. In contrast, newly developed anti-platelet agents have broad applications for the treatment of cardiovascular disease as they not only influence platelet function but are also considered to affect cardiac and vascular smooth muscle cell functions. Natural food products and nutraceutical agents also appear to modify cardiovascular abnormalities by affecting various platelet functions; however, the mechanisms of their actions remain to be investigated. Accordingly, this article is focused to discuss emerging pharmacologic, nutritional and nutraceutical interventions that may influence the prevention or progression of a broad range of cardiovascular diseases.

Future pharmacologic agents for treatment of heart failure in children

The addition of new agents to the armamentarium of treatment options for heart failure in pediatric patients is exciting and challenging. Administration of these therapies to pediatric patients will require careful scrutiny of the data and skilled application. Developmental changes in drug metabolism, excretion, and distribution are concerning in pediatric patients, and inappropriate evaluation of these parameters can have disastrous results. Manipulation of the neurohormonal pathways in heart failure has been the target of most recently developed pharmacologic agents. Angiotensin receptor blockers (ARBs), aldosterone antagonists, beta-blockers, and natriuretic peptides are seeing increased use in pediatrics. In particular, calcium sensitizing agents represent a new frontier in the treatment of acute decompensated heart failure and may replace traditional inotropic therapies. Endothelin receptor antagonists have shown benefit in the treatment of pulmonary hypertension, but their use in heart failure is still debatable. Vasopressin antagonists, tumor necrosis factor inhibitors, and neutral endopeptidase inhibitors are also targeting aspects of the neurohormonal cascade that are currently not completely understood. The future of pharmacologic therapies will include pharmacogenomic studies on new and preexisting therapies for pediatric heart failure. The education and skill of the practitioner when applying these agents in pediatric heart failure is of utmost importance.

Vasopressin receptor antagonists. Therapeutic potential in the management of acute and chronic heart failure

Despite the use of ACE inhibitors and beta-blockers, the morbidity and mortality of patients with chronic heart failure remains quite high. This has stimulated the development of new therapies, many based on the neurohormonal hypothesis. There are now multiple agents being developed for the treatment of heart failure designed to block many of the neurohormones that are increased in these patients. One of the hormones that is increased in chronic heart failure is vasopressin. Vasopressin reduces free water secretion and at high concentrations, causes vasoconstriction in the peripheral vasculature. Antagonists to vasopressin will promote free water excretion (aquaresis) and vasodilatation with a subsequent reduction in afterload. In theory, these agents would be beneficial for both acute exacerbations of heart failure (free water excretion) and chronic heart failure (neurohormonal blockade). We review the potential uses of these antagonists for these two conditions and the promising results of small, hemodynamic trials with the new vasopressin antagonists that have already been performed.

Development and therapeutic indications of orally-active non-peptide vasopressin receptor antagonists

Vasopressin (AVP) is a cyclic nonapeptide hormone that exhibits many physiological effects including free water reabsorption, vasoconstriction, cellular proliferation and adrenocorticotrophic hormone (ACTH) secretion. In a healthy organism, AVP plays an important role in the homeostasis of fluid osmolality and volume status. However, in several diseases or conditions such as the syndrome of inappropriate secretion of AVP (SIADH), congestive heart failure, arterial hypertension, liver cirrhosis, nephrotic syndrome, dysmenorrhoea and ocular hypertension, AVP may play an important role in their pathophysiology. Recently, orally-active non-peptide AVP receptor antagonists were developed by random screening of chemical entities and optimisation of lead compounds. These include agents specific for the V(1)-vascular and V(2)-renal AVP receptor subtypes. Dual V(1)/V(2) AVP receptor antagonists are also being studied. Some of these non-peptide receptor antagonists have been studied extensively, while others are currently under investigation. Potential therapeutic indications for AVP receptor antagonists comprise: 1) The blockade of V(1)-vascular AVP receptors in arterial hypertension, congestive heart failure, Raynaud's syndrome, peripheral vascular disease and dysmenorrhea. 2) The blockade of V(2)-renal AVP receptors in the syndrome of inappropriate secretion of vasopressin, congestive hart failure, liver cirrhosis, nephrotic syndrome and any state of excessive retention of free water and subsequent dilutional hyponatraemia. 3) The blockade of V(3)-pituitary AVP receptors in ACTH-secreting tumours. This review examines the pharmacology of orally-active non-peptide AVP receptor antagonists and their clinical applications.

Effect of SR 49059, a V1a vasopressin receptor antagonist, in Raynaud's phenomenon

OBJECTIVE

To assess whether vasopressin V1a receptor blockade reduces the abnormal vasoactive response to cold in patients suffering from Raynaud's phenomenon (RP).

METHODS

SR 49059, an orally active, non-peptidic vasopressin V1a receptor antagonist, was given orally (300 mg once daily) to 20 patients with RP in a single-centre, double-blind, placebo-controlled, randomized cross-over study with two 7-day periods of treatment separated by 21 days of washout. Bilateral finger systolic blood pressure and skin temperature were assessed before and after immersion of the hand in cold water for 3 min (15 degrees C) during the screening phase and three times (before and 2 and 4 h after drug intake) on days 1 and 7 of each of the two treatment periods. Recovery of digital pressure and skin temperature was measured 0, 10, 20 and 32 min after the end of the cold immersion test.

RESULTS

SR 49059 significantly attenuated the cold-induced fall in systolic pressure by 14.5% (95% confidence interval 0-29; P = 0.045) on the most affected hand on day 7 compared with placebo. Temperature recovery after the end of the cold test showed a trend to enhancement 2 and 4 h after SR 49059 on day 7 (P = 0.060 and P = 0.062 respectively). The beneficial effects on finger pressure and temperature recovery were obtained without changes in supine blood pressure or in heart rate.

CONCLUSION

SR 49059 given orally once a day for 7 days to patients with RP showed favourable effects compared with placebo on finger systolic pressure and temperature recovery after cold immersion, without inducing side-effects.

Effect of SR49059, an orally active V1a vasopressin receptor antagonist, in the prevention of dysmenorrhoea

OBJECTIVE

To investigate the clinical effect of SR49059 when given shortly before the onset of menstruation as a preventative treatment of dysmenorrhoea.

DESIGN

A double-blind, randomised, placebo-controlled, cross-over trial in complete block design (three periods, three treatments).

SETTING

A clinical research organisation in Paris, France.

PARTICIPANTS

Women aged 18-35 years suffering from primary dysmenorrhoea.

INTERVENTIONS

In each of three menstrual cycles, women reported to the study centre and were given a daily dose of either placebo, 100 mg or 300 mg SR49059 from a minimum of 4 hours up to a maximum of three days before the onset of bleeding and/or menstrual pain. If this did not control the pain, women were allowed once a day to take a second dose of study treatment providing that at least 4 hours had passed since the first drug intake.

MAIN OUTCOME MEASURES

Intensity of menstrual pain recorded by means of a visual analogue scale. Rating of symptoms of dysmenorrhoea (mainly back and pelvic pain) in relation to functional capacity (Sultan score). Self-assessment of menstrual blood loss in a menstrual diary record.

RESULTS

Analysis of intensity of menstrual pain, as recorded by visual analogue scale and Sultan pain score (back and pelvic pain) during the first 24 hours of dysmenorrhoea, showed a dose-related effect of SR49059. The 300 mg dose of SR49059 was significantly more effective than placebo. Similarly, a dose-related effect of SR49059 was shown on total Sultan score. SR49059 was well tolerated and no significant effect on the bleeding pattern was noted.

CONCLUSIONS

This study showed for the first time a therapeutic effect of an orally active vasopressin V1a receptor antagonist in the prevention of dysmenorrhoea. Further studies are required to examine effect mechanisms and determine effective doses.

Effects of the nonpeptide V(1) vasopressin receptor antagonist SR49059 in hypertensive patients

We assessed the clinical and pharmacological profile of the orally active V(1) vascular vasopressin (AVP) receptor nonpeptide antagonist SR49059 (SR) during the osmotic stimulation of AVP release in hypertensive patients. In a double-blind crossover-versus-placebo study, 24 untreated stage I or II essential hypertensive patients (12 whites and 12 blacks) received a single 300 mg oral dose of SR 2 hours before the stimulation of AVP secretion with a 5% hypertonic saline infusion. Hemodynamic, humoral, and hormonal parameters were monitored for up to 28 hours after drug administration. SR did not alter blood pressure or heart rate before the saline infusion and did not reduce the blood pressure increment induced by the hypertonic saline infusion. However, the blood pressure peak at the end of the hypertonic saline infusion was slightly lower in the presence of SR (P=0.04). Heart rate was significantly faster between 4 and 6 hours after SR administration (P=0.02). The rise in plasma sodium and osmolality triggered by the saline infusion was not modified by SR, but AVP release was slightly greater in the presence of SR (P<0.0003). AVP-induced aggregation of blood platelets in vitro was significantly reduced by SR, with a peak effect 2 hours after drug administration that coincided with the SR peak plasma concentration. Plasma renin activity and aldosterone before and after the saline infusion were not modified by SR. Urine volume and osmolality were not altered by SR administration. SR effects were similar in the 2 ethnic groups as well as in salt-sensitive versus salt-resistant patients. In a situation of AVP osmotic release and volume expansion in hypertensive patients, a single oral dose of the V(1) vascular AVP receptor nonpeptide antagonist SR49059, which is able to block AVP-induced platelet aggregation, exerts a transient vasodilation effect that is not associated with a sustained blood pressure reduction. SR49059 is a pure V(1) vascular receptor antagonist that is devoid of V(2) renal receptor actions.