Use of conivaptan for refractory syndrome of inappropriate secretion of antidiuretic hormone in a pediatric patient

Vaptans for oedematous and hyponatraemic disorders in childhood: A systematic literature review

AIMS

The aim of this study was to systematically review the use of vaptans (nonpeptide vasopressin receptor antagonists) in children.

METHODS

Through a database search (Web of Science, the National Library of Medicine, Excerpta Medica), we identified case series and case reports and extracted clinical and laboratory data.

RESULTS

Twenty-six articles, published since 2008, reported on 226 patients. Among 115 children with hyponatraemic (n = 63) and oedematous disorders (n = 52), a 48 hour course of tolvaptan with an initial dose of 0.38 ± 0.27 mg/kg was administered in 106 cases, while intravenous conivaptan was reported in nine cases. An increase (P < .02) in urine output was shown in both oedematous (from 3.2 ± 2.0 to 5.3 ± 6.7 mL/kg/day) and hyponatraemic (from 3.0 ± 1.5 to 4.4 ± 2.3 mL/kg/day) patients. In these latter, sodium increased from 125 ± 6 to 133 ± 6 mmol/L (P < .0001). The increase in sodium level correlated with its basal value, but not with the administered vaptan dose. Among 111 children undergoing cardiac surgery, after tolvaptan 0.21 ± 0.01 mg/kg/day, mostly combined with conventional diuretics, an increase in diuresis by 41 ± 4% was seen within 24 hours (P < .0001). Similarly, a single add-on dose of tolvaptan 0.45 mg/kg allowed a reduced additional intravenous furosemide administration (0.26 ± 0.23 vs 0.62 ± 0.48 mg/kg, P < .005). Side effects were rarely reported, and included excessive thirst and xerostomia in seven, skin rash in one and elevated aminotransferases in one patient(s).

CONCLUSION

Vaptans appear to be safe for oedematous and hyponatraemic disorders also in children. Although they increase diuresis and natraemia, no superiority to traditional diuretics and sodium supplements has been demonstrated. Reported side effects are rare and non-serious.

Efficiency of Single Dose of Tolvaptan Treatment During the Triphasic Episode After Surgery for Craniopharyngioma

Inappropriate antidiuretic hormone syndrome (SIADH) may develop after intracranial surgery. SIADH in the pediatric age group is usually encountered in patients with an intracranial mass both before and after surgery. Fluid restriction is the standard therapy in SIADH. However, a resistant, hyponatremic pattern may be encountered in some cases. Vaptans have been recently introduced for treatment of hyponatremia due to SIADH. There is inadequate data concerning tolvaptan treatment in pediatric patients. We present a 13 year-old female with SIADH of triphasic episode who was transferred to our clinic after surgery for craniopharyngioma. Resistant hyponatremia did not resolve despite fluid restriction and hypertonic saline support. The patient responded rapidly to a single dose of tolvaptan, with no adverse effect, which resulted in successful control of her SIADH.

Treatment of Severe Hypervolemic Hyponatremia in a Child With Pneumonia

A 21-month-old boy came to our attention because of pneumonia. His weight increased before presentation, and his blood test results showed hyponatremia (116 mEq/L), low plasma osmolarity (241 mOsm/L), and high urine osmolarity (435 mOsm/L). He was treated with 0.9% sodium chloride solution and intravenous furosemide, and sodium levels rose up to 135 mEq/L in 36 hours. No standard treatment is available for severe hyponatremia in children. The use of vaptans in pediatric patients is described in literature, but it lacks evidence about safety and effectiveness. We suggest that furosemide administration plus salt replacement is effective in restoring normal values of plasma sodium concentration in severe euvolemic and hypervolemic hyponatremia.