Patients and their physicians are often thrown into doubt by the excretion of apparently intact tablets in stools after oral drug administration. This occurs whenever patients receive certain pharmaceutical forms designed to prolong the rate of drug release. The active compound is continuously released during intestinal passage of these pharmaceutical forms and their insoluble coats are visibly excreted into stools wholly or in part. The assumption that the drug was not released from the tablet in these cases is therefore erroneous and no further action is required.