According to the invention there is provided a method of treating a component of a medicament dispenser device, the component having one or more surfaces which come into contact with the medicament during storage or use of the device, the method including the steps of: providing said component； and coating at least one of said surfaces by plasma deposition thereby to inhibit surface deposition or degradation of the medicament, wherein at least part of the plasma deposition is performed under DC bias control.
