The present invention relates to a film comprising an alginate salt of a monovalent cation or a mixture of alginate salts containing at least one alginate salt of a monovalent cation, and an antagonist of an opioid receptor, an inverse agonist of an opioid receptor, or a prodrug thereof. The present invention further relates to methods for manufacturing such a film, and the use of such a film in the treatment of a human patient, in particular the use of such a film in the treatment of the effects of acute opioid overdose, or the use of such a film in reducing the risk of opioid abuse.