The change has been made because the nasal forms of desmopressin have been associated with most of the serious adverse effects reported in patients with PNE. Rare, serious adverse effects have included hyponatraemia, water intoxication and convulsions.
Hyponatraemia was reported at a rate of approximately 15 cases per 100,000 patient years of exposure for nasal formulations of desmopressin and six cases per 100,000 patient years for oral formulations of desmopressin. Hyponatraemia was predominantly associated with overdose, excessive fluid intake or inappropriate use.
For the management of patients on desmopressin nasal spray for PNE the MHRA advises that:
- Patients may complete their current course of treatment with desmopressin nasal spray.
- At the next routine review, patients requiring continued treatment should be prescribed only an oral form of desmopressin.
- All patients starting treatment with oral desmopressin should start at the lowest recommended dose regardless of their previous spray dose. This should be increased only if necessary to achieve control of symptoms.
The risk of hyponatraemia with oral desmopressin can be reduced by following the advice in the summary of product characteristics and the patient information leaflet.