Desmopressin is the generic name for a nasal spray designed to stop bedwetting. It is marketed in the US by Rhone-Poulenc as DDAVP, and by Ferring as Desmospray in the UK.
It can be taken by children as young as six years of age, who are advised to take 10 mcg (microgramme) in each nostril before going to sleep. The ideal dosage is arrived at only by trial and error, with the minimum being 10 mcg, going up to 40 mcg. The dose sometimes has to be increased after six months' usage,when the effects seem to diminish. Any patient who has taken the drug that long has gone further than medicine; trials have tested the drug and reactions for only four to eight weeks' usage.
A dose that is too high can result in headaches, nausea, nasal congestion, rhinitis, flushing, abdominal cramps, nosebleeds, sore throat, cough and upper respiratory infection.
Because it is an antidiuretic, desmopressin has the effect of reducing urine output as well as the movement of blood plasma. This latter effect can, on rare occasions, result in seizures and even coma.
Another major worry, particularly among smaller children, is water intoxication, which can occur if a child drinks too much water before going to bed while on the drug.
More common reactions include depression, dizziness, rash, conjunctivitis and other eye disorders.
Groups who should not be given the drug include those with a history of coronary problems, and those with fluid imbalance, such as cystic fibrosis sufferers. Trials on pregnant women and breastfeeding mothers have never been carried out.
The drug can also be supplied intravenously, although cases of anaphylactic shock have been reported.