A container comprising a closure means coated by an inert fluorinated material and containing a liquid pharmaceutical composition. In particular, the container comprises a closure means coated by TEFLON (polytetrafluoruethylene (PTFE)) and contains a HSA-free Interferon-β formulation having the following composition: 30 to 100 μg/ml of interferon-β, an isotonicity agent, 0.1 to 2 mg/ml of Poloxamer 188, at least 0.12 mg/ml of L-Methionine and a buffer solution capable of maintaining the pH of the liquid formulation at a value between 3.0 and 4.0.