Oxytocin Intranasal Administrations in Children With Prader-Willi Syndrome Aged From 3 to 12 Years

The study drug is oxytocin in intra-nasal administration, Syntocinon®, reconditioned as a placebo-like spray. The dosage administered will be 8 International Unit, ie 1 spray (4 International Unit per spray) in each nostril per day for the first 12 weeks, in 3 and 6 years old patients. The dosage administered will be 16 International Unit or 2 sprays in each nostril per day for the first 12 weeks, in 3 to 6 years old patients.

Placebo should be used as a spray, similar to that of the oxytocin. The dosage administered will be 1 spray in each nostril per day for the first 12 weeks in 3 to 6 years old patients. The dosage administered will be 2 sprays in each nostril per day for the first 12 weeks, in 7 to 12 years old patients.

Each patient will receive oxytocin in open label (Syntocinon® not reconditioned) from week 13 to week 24 according to the same dosages.