Conivaptan

Conivaptan is a nonpeptide medication that acts as a dual antagonist of vasopressin receptors, targeting both V1A and V2 receptors. By blocking these receptors, it promotes free water excretion (aquaresis) in the kidneys without significant loss of electrolytes, which can help raise serum sodium in cases of hyponatremia associated with excess body water. It is used primarily in hospitalized adults for euvolemic or hypervolemic hyponatremia when fluid restriction is insufficient or not feasible.

Pharmacology and administration details are oriented toward short-term hospital use. Conivaptan is administered intravenously and typically given as a loading dose followed by a maintenance infusion for several days. Because the drug couples vasopressin antagonism with rapid shifts in serum sodium, patients require close monitoring of electrolytes and clinical status to avoid overly rapid correction of hyponatremia, which can lead to osmotic demyelination syndrome. Blood pressure and volume status should be monitored due to potential hypotension from vasodilatory effects.

Pharmacokinetics and interactions involve hepatic metabolism, with significant involvement of the CYP3A4 system. Conivaptan can interact with other drugs processed by CYP3A4 and may affect the levels of concomitant medications such as certain immunosuppressants, sedatives, and statins. Given these interactions and the risk of rapid sodium correction, use is restricted to controlled clinical settings with appropriate laboratory and clinical monitoring.

Adverse effects commonly observed include orthostatic hypotension, infusion-site reactions, and electrolyte disturbances. It is generally not used for chronic hyponatremia and is not appropriate for hypovolemic hyponatremia in most cases.