Intranasal delivery devices include dosage forms containing medical compositions for use in the intranasal devices, and methods of delivering medical compositions to the nasal mucosa of users. The devices dispense a predetermined quantity of fluid into the nasal passage of a user, in which the predetermined quantity of fluid is contained in, or produced in a dosage form or blister that is crushed by a plunger with sufficient force to drive the dosage form against a piercing mechanism, piercing the dosage form and forcing the liquid contents from the dosage form and through a delivery channel into a spray to be directed into the nasal passage of a user. The plunger is connected to a trigger device by a linkage that confers a mechanical advantage to the trigger mechanism.