A-B) During biological response and PK study: the standard dose (0.3 m g/Kg) of DDAVP should be diluted in 50-100 ml of saline and infused intravenously in a 30 minutes time. Since we want to combine biological response, with PK analysis together with clinical efficacy, time post-DDAVP must be calculated always starting from the beginning of the infusion (baseline): i.e. 0.5 h from baseline means immediately at the end of DDAVP infusion; 2 hours from baseline means 1.5 hours after the end of infusion.

In case of biological response (in all cases), blood samples must be collected at baseline and 0.5. 1, 2, 4 hours from baseline. The two hours time is critical for analysis.

In case of PK study (in 30-40 cases), an additional baseline sample must be collected 1 hour before the start of infusion (baseline 1), baseline, 0.5, 1, 2, 4 hours with additional withdrawals at 6, 8, 12, 24 hours from baseline, to calculate the half-lives of both VWF and FVIII:C activities

The same standard dose (0.3 m g/Kg) of DDAVP can be injected intravenously (in a 30 minutes time as for biological response and PK test) or subcutaneously. In case of intranasal administration, a total dose of 300 m g of DDAVP should be slowly applied into both nasal cavities. In hospitalized patients only, blood samples must be taken to measure VWF & FVIII:C activities at baseline and two hours after baseline only to correlate them with the biological response previously evaluated in the same patient at the same time interval.