The present invention relates to a method for dosing a pharmaceutical product in a packaging machine comprising at least one volumetric dosing unit with a dosing chamber. The method comprises metering a volume of a first component, weighing the first component, introducing the first component into a package and metering a volume of a second component, introduceg the second component into the package and weighing of the package into which the components have being introduced.The invention further relates to a system for dosing a pharmaceutical product in a packaging machine comprising at least one volumetric dosing unit with a dosing chamber. The system comprises at least one volumetric dosing unit for metering a volume of the components. Further, means for introducing the said components into a package and means for weighing the components and the package are comprised. The means for weighing comprises a first weighing unit for weighing the package and the components, and a second weighing unit for weighing the first component after metering the first component by volume and before introducing the first component into the package.