The card has no method of preparation (decoction or infusion), no amount and no length of use. It gives only the composition – buckthorn bark 100% – and a contraindication: individual intolerance. For how to prepare it and how much to take, check the packaging.
General information (not a manufacturer's instruction): buckthorn bark is used in medicine as a laxative, so the method, dose and duration are better agreed with a doctor if you are unsure.