Terlipressin therapy for moderate-to-severe hyponatraemia in patients with liver failure

A gold mine for drug discovery: Strategies to develop cyclic peptides into therapies

As a versatile therapeutic modality, peptides attract much attention because of their great binding affinity, low toxicity, and the capability of targeting traditionally "undruggable" protein surfaces. However, the deficiency of cell permeability and metabolic stability always limits the success of in vitro bioactive peptides as drug candidates. Peptide macrocyclization is one of the most established strategies to overcome these limitations. Over the past decades, more than 40 cyclic peptide drugs have been clinically approved, the vast majority of which are derived from natural products. The de novo discovered cyclic peptides on the basis of rational design and in vitro evolution, have also enabled the binding with targets for which nature provides no solutions. The current review summarizes different classes of cyclic peptides with diverse biological activities, and presents an overview of various approaches to develop cyclic peptide-based drug candidates, drawing upon series of examples to illustrate each strategy.

Approach and management of dysnatremias in cirrhosis

Hypervolemic (dilutional) hyponatremia is the most common dysnatremia in cirrhosis, with a prevalence close to 50% in patients with ascites, while hypovolemic hyponatremia occurs in a minority of cases. Hyponatremia carries a poor prognosis, being associated with increased mortality and reduced survival after liver transplantation. Hypernatremia is rarer and is also associated with an adverse prognosis. Increased non-osmotic secretion of arginine vasopressin and altered renal tubular sodium handling due to impaired free water generation are the mechanisms leading to hypervolemic hyponatremia, while diuretic-induced fluid loss is the main cause of hypovolemic hyponatremia. Hypernatremia usually follows hypotonic fluid losses due to osmotic diuresis (glycosuria) or lactulose-induced diarrhea. The main clinical manifestations of dysnatremias are due to their effects on the central nervous system: astroglial cell hyperhydration follows hyponatremia-an abnormality that exacerbates ammonia neurotoxicity-while the opposite abnormality occurs with hypernatremia. Asymptomatic or mildly symptomatic hypervolemic hyponatremia is mainly managed by correcting of precipitating factors and non-osmotic fluid restriction. Severe, life-threatening hyponatremia requires hypertonic saline infusion, avoiding rapid and complete correction of serum sodium concentration to prevent neurological sequelae such as osmotic demyelination. V₂ receptor blockade by vaptans may be considered in patients with sustained hyponatremia waitlisted for liver transplantation. Diuretic withdrawal and plasma volume expansion are required in hypovolemic hypernatremia. Prompt recognition, removal of the precipitating factor(s) and non-osmotic fluid administration represent the mainstays of hypernatremia management. Rapid correction of long-standing hypernatremia can lead to cerebral edema and has to be avoided.

Terlipressin: Current and emerging indications in chronic liver disease

Terlipressin is an analogue of vasopressin that has potent vasoactive properties and has been available for use in most countries for nearly two decades. It has both established roles and emerging indications in the management of complications of decompensated chronic liver disease. We explore historic and emerging literature regarding the use of terlipressin for a range of indications including hepatorenal syndrome, portal hypertensive bleeding, and disruptions in sodium homeostasis. Novel methods of infusion-based terlipressin administration including the beneficial effect in reduction of adverse events are explored, in addition to new indications for the use of terlipressin in decompensated cirrhosis in an outpatient setting.

Hyponatremia in Patients with Cirrhosis of the Liver

Hyponatremia is common in cirrhosis. It mostly occurs in an advanced stage of the disease and is associated with complications and increased mortality. Either hypovolemic or, more commonly, hypervolemic hyponatremia can be seen in cirrhosis. Impaired renal sodium handling due to renal hypoperfusion and increased arginine-vasopressin secretion secondary to reduced effective volemia due to peripheral arterial vasodilation represent the main mechanisms leading to dilutional hyponatremia in this setting. Patients with cirrhosis usually develop slowly progressing hyponatremia. In different clinical contexts, it is associated with neurological manifestations due to increased brain water content, where the intensity is often magnified by concomitant hyperammonemia leading to hepatic encephalopathy. Severe hyponatremia requiring hypertonic saline infusion is rare in cirrhosis. The management of asymptomatic or mildly symptomatic hyponatremia mainly rely on the identification and treatment of precipitating factors. However, sustained resolution of hyponatremia is often difficult to achieve. V2 receptor blockade by Vaptans is certainly effective, but their long-term safety, especially when associated to diuretics given to control ascites, has not been established as yet. As in other conditions, a rapid correction of long-standing hyponatremia can lead to irreversible brain damage. The liver transplant setting represents a condition at high risk for the occurrence of such complications.