Method and apparatus an aerosol container

A method of introducing into a container a suspension or solution of a pharmaceutical substance in a propellant held under pressure, the suspension or solution being circulated in a line which includes a filling head, said method comprising:

• bringing said filling head into communication with the container;
• introducing a quantity of such suspension or solution into the container through the filling head;
• introducing a quantity of high pressure propellant without any of said pharmaceutical substance into the filling head while it is still in communication with the container, thereby to flush through any suspension or solution remaining in the filling head;
• said filling head permitting introduction of only one of the suspension or solution on the one hand and the propellant alone on the other hand at any one time, the propellant which contains said pharmaceutical substance and the propellant without any of said pharmaceutical substance being the same, said propellant being 1,1,1,2-tetrafluoroethane;
• and
• withdrawing the filling head from the container.