Stimate® Nasal Spray contains as active substance, desmopressin acetate, which is a synthetic analogue of the natural hormone arginine vasopressin. One spray or 0.1 mL (150 µg) of Stimate® Nasal Spray solution has an antidiuretic activity of about 600 IU.
Desmopressin acetate has been shown to be more potent than arginine vasopressin in increasing plasma levels of Factor VIII activity in patients with hemophilia and von Willebrand's disease Type I.
Dose-response studies were performed in healthy persons using doses of 150 to 450 µg, administered as one to three sprays. The response to Stimate® Nasal Spray is dose-related, with maximal plasma levels of 150 to 250 percent of initial concentrations achieved for both Factor VIII and von Willebrand factor.1 The increase is rapid and evident within 30 minutes, reaching a maximum at about 1.5 hours.1
The percentage increase of Factor VIII and von Willebrand factor levels in patients with mild hemophilia A and von Willebrand's disease was not notably different from that observed in normal healthy individuals when treated with 300 µg of Stimate® Nasal Spray.1-4 In patients with von Willebrand's disease, levels of Factor VIII coagulant activity and von Willebrand factor antigen remained greater than 30 U/dL for 8 hours after a 300 µg dose of Stimate® Nasal Spray.5 After 300 µg of Stimate® Nasal Spray, the percentage increase of Factor VIII and von Willebrand factor levels in patients with mild hemophilia A and von Willebrand's disease was less than observed after 0.3 µg/kg of intravenous desmopressin acetate.2-4
Plasminogen activator activity increases rapidly after intravenous desmopressin acetate infusion, but there has been no clinically significant fibrinolysis in patients treated with desmopressin acetate.
The effect of repeated intravenous desmopressin acetate administration when doses were given every 12 to 24 hours has generally shown a diminution of the Factor VIII activity increase noted after a single dose. It is possible to reproduce the initial response in some patients after an interval of one week, but other patients may require as long as 6 weeks.2,4,6
The half-life of Stimate® Nasal Spray was between 3.3 and 3.5 hours, over the range of intranasal doses, 150 to 450 µg.1 Plasma concentrations of Stimate® Nasal Spray were maximal approximately 40 to 45 minutes after dosing.1
The bioavailability of Stimate® Nasal Spray when administered by the intranasal route as a 1.5 mg/mL solution is between 3.3 and 4.1 percent.1
The change in structure of arginine vasopressin to desmopressin acetate has resulted in a decreased vasopressor action and decreased actions on visceral smooth muscle relative to the enhanced antidiuretic activity, so that clinically effective antidiuretic doses are usually below threshold levels for effects on vascular or visceral smooth muscle.