[en] Described is a flexible drainage tube of good tissue tolerance developed for the postoperative continuous withdrawal of secretions from wounds which - owing to the addition of an active ingredient in sustained release dosage form (pentosanpolysulfate stored in the molecular sieve) - inhibits or considerably delays clogging as a result of coagulation processes. The tube is made of a mixture of natural or silicone rubbers and 4% coagulation inhibitor that is extruded onto a metal mandrel, crosslinked using electron rays (100 kGy, 20 s) and simultaneously sterilised. The mandrel is subsequently removed. In vitro trials (using blood plasm for open flow systems and blood for circulatory flow systems) provided evidence in confirmation of a continuous regular release of active ingredient that inhibited coagulation processes over prolonged periods of time. (orig.)