An injection syringe useful in the medical arts for injecting high viscosity fluids or pastes, particularly in endoscopic applications. The syringe (14) includes a force multiplying mechanism to infuse viscous medicaments such as collagen or polytetrafluoroethylene paste, with a controlled metering action. The force multiplying mechanism is provided by the combination of lower piston cylinder chamber (16) that intersects with an upper cylinder chamber (18), wherein the piston (15) is connected to a piston advancing means (17) on a lever pivot arm (11).
