Therapeutic: electrolyte modifiers
Pharmacologic: vasopressin receptor antagonists
Euvolemic hyponatremia, which may be due to inappropriate secretion of antidiuretic hormone, hypothyroidism, adrenal insufficiency, or pulmonary disorders. Treatment of hypervolemic hyponatremia in hospitalized patients.
Antagonizes vasopressin at V2 receptor sites in renal collecting ducts, resulting in excretion of free water. Therapeutic Effects: Restoration of normal fluid and electrolyte status.
Adverse Reactions/Side Effects
CNS: headache, confusion, insomnia. CV: hypertension, hypotension. GI: diarrhea. GU: polyuria. F and E: dehydration, hypokalemia, hypomagnesemia, hyponatremia. Local: injections site reactions. Misc: fever, thirst.
PHYSICAL THERAPY IMPLICATIONS
Examination and Evaluation
Monitor neuromuscular signs of fluid and electrolyte imbalances, including low levels of sodium (hyponatremia), potassium (hypokalemia), and magnesium (hypomagnesemia). Signs of imbalances include headache, confusion, lethargy, irritability, weakness, muscle cramping, and muscle hyperexcitability and tetany. Notify physician immediately if these signs occur.
Assess blood pressure (BP) and compare to normal values (See Appendix F). Report changes in BP, either a problematic decrease in BP (hypotension) or a sustained increase in BP (hypertension).
Monitor IV injection site for pain, swelling, and irritation. Report prolonged or excessive injection site reactions to the physician.
Instruct patient and family/caregivers to maintain adequate fluid intake and avoid dehydration.
Instruct patient and family/caregivers to report other troublesome side effects such as severe or prolonged headache, sleep loss, fever, increased urination, or diarrhea.
Absorption: IV administration results in complete bioavailability.
Protein Binding: 99% protein bound.
Metabolism and Excretion: Metabolized solely by the CYP3A4 enzyme system. 83% excreted in feces as metabolites, 12% in urine (as metabolites).
Contraindicated in: Hypersensitivity; Hypovolemic hyponatremia; Concurrent use of ketoconazole, itraconazole, clarithromycin, ritonavir, or indinavir.
Use Cautiously in: Impaired hepatic or renal function; OB: Pregnancy and lactation (safety not established); Pedi: Children (safety not established).
Drug-Drug: Blood levels and effects are ↑ by ketoconazole, itraconazole, clarithromycin, ritonavir, or indinavir (concurrent use is contraindicated). ↑ blood levels and may ↑ effects of midazolam, simvastatin, amlodipine, and other drugs metabolized by CYP3A4; careful monitoring recommended. May also ↑ digoxin levels.