Reported Adverse Drug Reaction Cases
- Ferring Pharmaceuticals Pty Ltd. Product Information for: Minirin Nasal Spray, Minirin Tablets, Minirin, Octistim.
Desmopressin and hyponatraemia
Desmopressin (Minirin, Octostim) is a synthetic analogue of the natural antidiuretic hormone (ADH) arginine vasopressin and is currently available in nasal spray, nasal solution, tablet, sublingual wafer, and injection form. Desmopressin nasal spray and tablets are indicated for primary nocturnal enuresis (where an enuresis alarm has failed or is contraindicated) and cranial diabetes insipidus; desmopressin nasal solution and tablets are indicated for cranial diabetes insipidus and certain blood disorders.
Desmopressin acts on the ADH receptors in the kidneys, mimicking the effects of ADH and therefore preventing excessive loss of water. In the presence of excessive fluid intake in patients taking desmopressin, dilutional hyponatremia can occur. If this occurs quickly then lack of adaptation can result in a shift of water intracellularly and cerebral oedema, which may present with anorexia, nausea and vomiting, difficulty concentrating, confusion, lethargy, agitation, headache, and seizures.
The risk of hyponatremia is greater with desmopressin intranasal preparations than with the oral forms. In 2007, the TGA amended the indications for desmopressin nasal spray to restrict use only when it is not feasible to use an oral formulation. Sponsors were also required to amend all desmopressin product information documents to strengthen precautionary statements relating to the potential for hyponatraemia and to provide information on this potentially serious reaction.1
To date, ADRAC has received 68 reports of adverse reactions associated with the use of desmopressin, including 17 reports of convulsions (with or without reported hyponatremia), and 10 further reports of hyponatremia alone. Of 12 reports of convulsions or hyponatremia following the use of desmopressin nasal spray, 7 involved children under 13 years of age.
Prescribers are reminded that desmopressin nasal spray and tablets should be used in the treatment of nocturnal enuresis only when an enuresis alarm has failed or is contraindicated, and that tablets should be used in preference to intranasal preparations because of a possible increased risk of hyponatremia. Avoidance of excessive fluid intake should be advised during treatment with desmopressin. The ongoing need for these products should be reviewed periodically in patients taking desmopressin long-term.Reference
Australian Adverse Drug Reactions Bulletin, Volume 27, Number 4, August 2008