indication

For the treatment of euvolemic or hypervolemic hyponatremia (e.g. the syndrome of inappropriate secretion of antidiuretic hormone, or in the setting of hypothyroidism, adrenal insufficiency, pulmonary disorders, etc.) in hospitalized patients.

pharmacology

Conivaptan is a nonpeptide, dual antagonist of arginine vasopressin (AVP) V_1A and V₂ receptors. The level of AVP in circulating blood is critical for the regulation of water and electrolyte balance and is usually elevated in both euvolemic and hypervolemic hyponatremia. The AVP effect is mediated through V₂ receptors, which are functionally coupled to aquaporin channels in the apical membrane of the collecting ducts of the kidney. These receptors help to maintain plasma osmolality within the normal range by increasing permeability of the renal collecting ducts to water. Vasopressin also causes vasoconstriction through its actions on vascular _1A receptors. The predominant pharmacodynamic effect of conivaptan in the treatment of hyponatremia is through its V₂ antagonism of AVP in the renal collecting ducts, an effect that results in aquaresis, or excretion of free water. Conivaptan's antagonist activity on V_1A receptors may also cause splanchnic vasodilation, resulting in possible hypotension or variceal bleeding in patients with cirrhosis. The pharmacodynamic effects of conivaptan include increased free water excretion (i.e., effective water clearance [EWC]) generally accompanied by increased net fluid loss, increased urine output, and decreased urine osmolality.

mechanism of action

Conivaptan is a dual AVP antagonist with nanomolar affinity for human arginine vasopressin V_1A and V₂ receptors in vitro. This antagonism occurs in the renal collecting ducts, resulting in aquaresis, or excretion of free water.

toxicity

Although no data on overdosage in humans are available, conivaptan has been administered as a 20 mg loading dose on Day 1 followed by continuous infusion of 80 mg/day for 4 days in hyponatremia patients and up to 120 mg/day for 2 days in CHF patients. No new toxicities were identified at these higher doses, but adverse events related to the pharmacologic activity of conivaptan, e.g. hypotension and thirst, occurred more frequently at these higher doses.

biotransformation

CYP3A4 is the sole cytochrome P450 isozyme responsible for the metabolism of conivaptan. Four metabolites have been identified. The pharmacological activity of the metabolites at V_1a and V₂ receptors ranged from approximately 3-50% and 50-100% that of conivaptan, respectively.

half life

5 hours

drug interactions

Alfuzosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alfuzosin. Concomitant use of alfuzosin with a strong CYP3A4 inhibitor is a listed contraindication according to alfuzosin prescribing information.

Almotriptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Almotriptan. Use an initial almotriptan dose of 6.25mg when using almotriptan with a strong CYP3A4 inhibitor, and do not exceed 12.5mg of almotriptan in any 24-hour period. Avoid concurrent use of almotriptan with a strong CYP3A4 inhibitor in patients with impaired hepatic or renal function.

Artemether: Conivaptan, a strong CYP3A inhibitor, may increase the toxicity of artemether by inhibiting its metabolism. Consider alternate therapy or allow at least 7 days to elapse between conivaptan and artemether therapy.

Bexarotene: Conivaptan may increase the serum concentration of CYP3A4 substrates such as bexarotene. Upon completion/discontinuation of conivaptan, allow at least 7 days before initiating therapy with drugs that are CYP3A4 substrates. Consider therapy modification.

Bezafibrate: Conivaptan may increase the serum concentration of CYP3A4 substrates like bezafibrates. Consider therapy modification. Conivaptan may increase the serum concentration of CYP3A4 substrates.

Bromazepam: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of bromazepam by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of bromazepam if conivaptan is initiated, discontinued or dose changed. Dosage adjustments may be required.

Budesonide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Budesonide (Systemic, Oral Inhalation). onsider reducing the oral budesonide dose when used together with a strong CYP3A4 inhibitor. This interaction is likely less severe with orally inhaled budesonide. Any patient receiving both budesonide and a strong CYP3A4 inhibitor should be monitored closely for signs/symptoms of corticosteroid excess.

Bupivacaine: Conivaptan may increase the serum concentration of CYP3A4 Substrates such as bupivacaine. Upon completion/discontinuation of conivaptan, allow at least 7 days before initiating therapy with drugs that are CYP3A4 substrates.

Buprenorphine: Conivaptan may increase the serum concentration of CYP3A4 Substrates like buprenorphine. Upon completion/discontinuation of conivaptan, allow at least 7 days before initiating therapy with drugs that are CYP3A4 substrates.

Caffeine: Conivaptan may increase the serum concentration of CYP3A4 substrates such as caffeine. Upon completion/discontinuation of conivaptan, allow at least 7 days before initiating therapy with drugs that are CYP3A4 substrates.

Cevimeline: Conivaptan may increase the serum concentration of CYP3A4 substrates such as cevimeline. Upon completion/discontinuation of conivaptan, allow at least 7 days before initiating therapy with drugs that are CYP3A4 substrates.

Colchicine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Colchicine. In patients with normal renal and hepatic function, reduce colchicine dose (for gout flares: to 0.6 mg x 1 dose, followed by 0.3 mg 1 hour later, with next dose no sooner than 3 days later; for gout flare prophylaxis: if target dose would otherwise be 0.6 mg daily, change to 0.3 mg every other day, and if target dose would otherwise be 0.6 mg twice daily, change to 0.3 mg daily; for Familial Mediterranean Fever: to no more than 0.6 mg/day) when using in combination with a strong CYP3A4 inhibitor such as clarithromycin or ritonavir. Increase monitoring for colchicine-related toxicity when using such combinations. Colchicine use is contraindicated in patients with impaired renal and/or hepatic function who are also receiving a strong CYP3A4 inhibitor.

Dantrolene: Conivaptan may increase the serum concentration of dantrolene by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of dantrolene if conivaptan is initiated, discontinued or dose changed.

Eplerenone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eplerenone. The combination of eplerenone with any strong CYP3A4 inhibitor is contraindicated.

Everolimus: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Everolimus. Everolimus prescribing information recommends avoiding concurrent use with strong CYP3A4 inhbitors.

Fentanyl: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fentanyl. Concurrent use of fentanyl with any CYP3A4 inhibitor may result in increased fentanyl concentrations and could increase or prolong adverse effects, including potentially fatal respiratory depression. Patients receiving fentanyl and any CYP3A4 inhibitor should be closely monitored for several days following initiation of the combination, and fentanyl dosage reductions should be made as appropriate.

Fesoterodine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Fesoterodine. Avoid fesoterodine doses greater than 4mg daily in patients who are also receiving strong CYP3A4 inhibitors.

Fluconazole: Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of Conivaptan. Concomitant use of conivaptan with strong CYP3A4 inhibitors (e.g., azole antifungals) is contraindicated.

Fluticasone Propionate: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fluticasone (Oral Inhalation). Concurrent use of orally inhaled fluticasone with strong CYP3A4 inhibitors is not recommended.

Halofantrine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fluticasone (Oral Inhalation). Concurrent use of orally inhaled fluticasone with strong CYP3A4 inhibitors is not recommended.

Itraconazole: Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of Conivaptan. Concomitant use of conivaptan with strong CYP3A4 inhibitors (e.g., azole antifungals) is contraindicated.

Ixabepilone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ixabepilone. The dose of ixabepilone must be reduced when used with strong inhibitors of CYP3A.1 In one published abstract, ixabepilone 20mg/m2 was the maximum tolerated dose in patients who were also receiving the CYP3A-inhibitor ketoconazole (400mg).

Ketoconazole: Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of Conivaptan. Concomitant use of conivaptan with strong CYP3A4 inhibitors (e.g., azole antifungals) is contraindicated.

Maraviroc: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Maraviroc. When used with a strong CYP3A4 inhibitor, the adult dose of maraviroc should be decreased to 150 mg twice daily. Maraviroc is contraindicated in patients with severe renal impairment (creatinine clearance less than 30 mL/min) receiving a strong CYP3A4 inhibitor. Maraviroc may be administered at a dose of 300 mg twice daily with concomitant tipranavir/ritonavir but not with other ritonavir combinations.

Methylprednisolone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Methylprednisolone. Consider methylprednisolone dose titration and/or adjustments in patients receiving strong CYP3A4 inhibitors (eg, azole antifungals, protease inhibitors) and monitor for increased steroid related adverse effects.

Nilotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nilotinib. Nilotinib prescribing information recommends avoiding concurrent use of nilotinib with strong inhibitors of CYP3A4.

Nisoldipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nisoldipine. Avoid concurrent use of nisoldipine with strong inhibitors of CYP3A4, as the combination may lead to substantial increases in nisoldipine concentrations.

Posaconazole: Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of Conivaptan. Concomitant use of conivaptan with strong CYP3A4 inhibitors (e.g., azole antifungals) is contraindicated.

Ranolazine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ranolazine. The manufacturer contraindicates the use of ranolazine and strong CYP3A4 inhibitors (such as the azole antifungals).1 Monitor for increased effects/toxicity of ranolazine during concomitant use.

Rivaroxaban: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Rivaroxaban. Consider avoiding use of rivaroxaban with any strong CYP3A4 inhibitors as many such agents are inhibitors of both CYP3A4 and P-glycoprotein. Use of rivaroxaban concomitantly with drugs that are strong inhibitors of both CYP3A4 and P-glycoprotein is specifically contraindicated.

Salmeterol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Salmeterol. Concurrent use of salmeterol with strong inhibitors of CYP3A4 is not recommended according to salmeterol prescribing information.

Saxagliptin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Saxagliptin. Limit saxagliptin dose to 2.5 mg/day and monitor for increased saxagliptin levels/effects (e.g., hypoglycemia) with concomitant administration of a strong CYP3A4 inhibitor (e.g., ketoconazole). Monitor for decreased saxagliptin levels/effects with discontinuation of concomitant CYP3A4 inhibitor.

Sildenafil: CYP3A4 Inhibitors (Strong) such as conivaptan may increase the serum concentration of Sildenafil. When sildenanfil is used for treatment of pulmonary arterial hypertension, concurrent use with strong CYP3A4 inhibitors is not recommended. When sildenafil is used for treatment of erectile dysfunction, consider using a lower starting dose of 25 mg in patients who are also taking a strong CYP3A4 inhibitor. Due to the particularly strong effects of ritonavir, sildenafil (for erectile dysfunction) doses greater than 25 mg per 48 hours are not recommended. Of note, the interaction between CYP3A4 inhibitors and sildenafil is predicted to be greater with orally administered than with injected sildenafil.

Tacrolimus: The strong CYP3A4 inhibitor, Conivaptan, may decrease the metabolism and clearance of Tacrolimus, a CYP3A4 substrate. Consider alternate therapy or monitor for changes in therapeutic and adverse effects of Tacrolimus if Conivaptan is initiated, discontinued or dose changed.

Tadalafil: Conivaptan may reduce the metabolism of Tadalafil. Concomitant therapy should be avoided if possible due to high risk of Tadalafil toxicity.

Tamoxifen: Conivaptan may increase the serum concentration of Tamoxifen by decreasing its metabolism. Monitor for increased adverse/toxic effects of Tamoxifen.

Tamsulosin: Conivaptan, a CYP3A4 inhibitor, may decrease the metabolism and clearance of Tamsulosin, a CYP3A4 substrate. Monitor for changes in therapeutic/adverse effects of Tamsulosin if Conivaptan is initiated, discontinued, or dose changed.

Telithromycin: Co-administration may result in altered plasma concentrations of Conivaptan and/or Telithromycin. Consider alternate therapy or monitor the therapeutic/adverse effects of both agents.

Temsirolimus: Conivaptan may inhibit the metabolism and clearance of Temsirolimus. Concomitant therapy should be avoided.

Teniposide: The strong CYP3A4 inhibitor, Conivaptan, may decrease the metabolism and clearance of Teniposide, a CYP3A4 substrate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Teniposide if Conivaptan is initiated, discontinued or dose changed.

Tiagabine: The strong CYP3A4 inhibitor, Conivaptan, may decrease the metabolism and clearance of Tiagabine, a CYP3A4 substrate. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Tiagabine if Conivaptan is initiated, discontinued or dose changed.

Ticagrelor: CYP3A4 Inhibitors (Strong) such as conivaptan may decrease serum concentrations of the active metabolite(s) of Ticagrelor. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ticagrelor. Avoid use of ticagrelor in combination with strong CYP3A4 inhibitors.

Tolterodine: Conivaptan may decrease the metabolism and clearance of Tolterodine. Adjust Tolterodine dose and monitor for efficacy and toxicity.

Toremifene: CYP3A4 Inhibitors (Strong) such as conivaptan may enhance the adverse/toxic effect of Toremifene. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Toremifene. Concurrent use of toremifene with strong CYP3A4 inhibitors should be avoided.

Tramadol: Conivaptan may increase Tramadol toxicity by decreasing Tramadol metabolism and clearance.

Trazodone: The CYP3A4 inhibitor, Conivaptan, may increase Trazodone efficacy/toxicity by decreasing Trazodone metabolism and clearance. Consider alternate therapy or monitor for changes in Trazodone efficacy/toxicity if Conivaptan is initiated, discontinued or dose changed.

Vardenafil: Conivaptan, a strong CYP3A4 inhibitor, may reduce the metabolism and clearance of Vardenafil. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of Vardenafil.

Venlafaxine: Conivaptan, a CYP3A4 inhibitor, may decrease the metabolism and clearance of Venlafaxine, a CYP3A4 substrate. Monitor for changes in therapeutic/adverse effects of Venlafaxine if Conivaptan is initiated, discontinued, or dose changed.

Verapamil: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of Veramapil, a CYP3A4 substrate, by decreasing its metabolism and clearance. Consider alternate therapy or monitor for changes in the therapeutic/adverse effects of Verapamil if Conivaptan is initiated, discontinued or dose changed.

Vilazodone: CYP3A4 Inhibitors (Strong) such as conivaptan may increase the serum concentration of Vilazodone. Limit maximum adult vilazodone dose to 20 mg/day in patients receiving strong CYP3A4 inhibitors.

Vinblastine: Conivaptan, a strong CYP3A4 inhibitor, may decrease the metabolism of Vinblastine. Consider alternate therapy to avoid Vinblastine toxicity. Monitor for changes in the therapeutic/adverse effects of Vinblastine if Conivaptan is initiated, discontinued or dose changed.

Vincristine: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of Vincristine by decreasing its metabolism. Consider alternate therapy to avoid Vincristine toxicity. Monitor for changes in the therapeutic and adverse effects of Vincristine if Conivaptan is initiated, discontinued or dose changed.

Vinorelbine: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of Vinorelbine by decreasing its metabolism. Consider alternate therapy to avoid Vinorelbine toxicity. Monitor for changes in the therapeutic and adverse effects of Vinorelbine if Conivaptan is initiated, discontinued or dose changed.

Voriconazole: Voriconazole, a strong CYP3A4 inhibitor, may increase the serum concentration of conivaptan by inhibiting its metabolism. Concomitant therapy is contraindicated.

Zolpidem: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of zolpidem by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zolpidem if conivaptan is initiated, discontinued or dose changed.

Zonisamide: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of zonisamide by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zonisamide if conivaptan is initiated, discontinued or dose changed.

Zopiclone: Conivaptan, a strong CYP3A4 inhibitor, may increase the serum concentration of zopiclone by decreasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of zopiclone if conivaptan is initiated, discontinued or dose changed.