Lung Cancer Patient With Euvolemic Hyponatremia

Diagnosis

Severe, chronic euvolemic hyponatremia secondary to SIADH related to small cell lung carcinoma.

Why VAPRISOL was chosen for treatment

VAPRISOL was selected based on its ability to raise serum sodium in patients with euvolemic hyponatremia
Treatment of hyponatremia facilitated the timely initiation of palliative chemotherapy and radiotherapy. Caution was exercised to avoid rapid correction of serum sodium greater than 10 mEq/L in 24 hours
VAPRISOL treatment via peripheral IV was administered on the oncology floor
Serum sodium was evaluated twice daily to monitor serum sodium changes

Initial Presentation

A 69-year-old white male with SIADH related to small cell lung carcinoma was referred to the nephrology service for evaluation of hyponatremia. Serum sodium on hospital admission was 120 mEq/L.^*

Medical History

Hypertension
Myocardial infarction
Hyperlipidemia
Left carotid endarterectomy
Transurethral resection of the prostate
Bladder cancer

Medications

Enalapril
Pravastatin
Metoprolol
Warfarin

Exam Findings

Vital Signs	Height: 5′ 10″, weight: 207 lb, temperature: 98.5° F, BP: 157/92 mm Hg, HR: 78 bpm
Lungs	Expiratory rhonchi and decreased breath sounds at both bases, R > L
Other	Chronic venous stasis changes in lower extremities, no focal neurologic deficits, no edema; oxygen saturation 93% on 2 L oxygen per nasal cannula

Patient’s progression from day 1 through day 4

	VITAL SIGNS		LAB VALUES
	BP (mm Hg)	HR (bpm)	BUN/Cr (mg/dL)	Serum (K+) (mEq/L)	Serum Osm (osm/kg)	Urine Osm (osm/kg)	Serum (Na+) (mEq/L)	NOTES
Day 1	170/85	69	19/0.9	4.7	258	696	120	A 30-minute bolus dose of VAPRISOL 20-mg IV administered, followed by a 20-mg continuous IV infusion administered over 24 hours; serum sodium evaluated 8 hours after first dose.
Day 2	148/75	63	19/1.1	5.2	262	600	124	A 20-mg continuous IV infusion of VAPRISOL administered over 24 hours; improvement in volume overload.
Day 3	139/71	70	20/1.0	4.0	265	540	132	Evaluate serum sodium twice daily.
Day 4	120/70	66	17/1.0	4.2	268	486	135	Evaluate serum sodium twice daily.

*Safety Considerations – Serum sodium, volume, and neurological status must be monitored frequently because VAPRISOL potentially can cause overly rapid correction of hyponatremia leading to serious sequelae, including osmotic demyelination syndrome. In susceptible patients, including those with severe malnutrition, alcoholism or advanced liver disease, slower rates of correction should be used. In clinical studies of VAPRISOL, the adverse event profile in elderly patients was similar to that seen in the general population¹

REFERENCE: 1. Vaprisol^® [Package Insert] Cumberland Pharmaceuticals Inc. Nashville, TN 2016

View Full Prescribing Information

Indication: VAPRISOL is indicated to raise serum sodium in hospitalized patients with euvolemic and hypervolemic hyponatremia.
Important Limitations: VAPRISOL has not been shown to be effective for the treatment of the signs and symptoms of heart failure and is not approved for this indication. It has not been established that raising serum sodium with VAPRISOL provides a symptomatic benefit to patients.

IMPORTANT SAFETY INFORMATION

CONTRAINDICATIONS
VAPRISOL is contraindicated in patients with hypovolemic hyponatremia. The coadministration of VAPRISOL with potent CYP3A inhibitors, such as ketoconazole, itraconazole, clarithromycin, ritonavir, and indinavir, is contraindicated. In addition, no benefit can be expected in patients unable to make urine.

WARNINGS & PRECAUTIONS
Hyponatremia associated with heart failure: Safety data on the use of VAPRISOL in these patients are limited. Consider other treatment options.
Overly rapid correction of serum sodium: Monitor serum sodium, volume and neurologic status and if the patient develops an undesirably rapid rate of rise of serum, VAPRISOL should be discontinued. If serum sodium concentration continues to rise, VAPRISOL should not be resumed. Serious neurologic sequelae, including osmotic demyelination syndrome, can result from over rapid correction of serum sodium. In susceptible patients, including those with severe malnutrition, alcoholism or advanced liver disease, slower rates of correction should be used.
Hypovolemia or Hypotension: For patients who develop hypovolemia or hypotension while receiving VAPRISOL, VAPRISOL should be discontinued, and volume status and vital signs should be monitored.
Infusion site reactions: Serious reactions have occurred. Administer through large veins and change infusion site every 24 hours.

ADVERSE REACTIONS
The most common adverse reactions (incidence ≥10%) reported in clinical trials were infusion site reactions (including phlebitis), pyrexia, hypokalemia, headache and orthostatic hypotension.

DRUG INTERACTIONS
Potent CYP3A inhibitors may increase the exposure of conivaptan and are contraindicated. Generally avoid CYP3A substrates. Exposure to coadministered digoxin may be increased and digoxin levels should be monitored.

USE IN SPECIAL POPULATIONS
Use in Patients with Hepatic Impairment
In patients with moderate to severe hepatic impairment, initiate VAPRISOL with a loading dose of 10 mg over 30 minutes followed by 10 mg/day as a continuous infusion for 2 to 4 days. If no rise in serum sodium, VAPRISOL may be titrated upward to 20 mg/day.