Ghost-Pill

Introduction

A patient who is taking Glucophage XR 500 mg came to the pharmacy concerned that she had seen some tablet-like structures in her stool.

  • She asked if she was still getting the full dose of medication if the tablet was not dissolving.



Facts

With some controlled-release formulations, it is expected that the empty intact shell that housed the medicine ("ghost-pill" or "ghost-tablet"), or other insoluble formulation parts will appear in the stools.

  • This is because controlled-release formulations (tablets, capsules and their parts) are designed to either disintegrate slowly to release the medicine over a predetermined period or remain intact.



Examples of Medicines

Some examples of medicine that can appear in the stool include:

  • Adefin XL (nifedipine)
  • Cardura XL (doxazosin)
  • Concerta (methylphenidate)
  • Duride (isosorbide mononitrate)
  • Effexor-XR (venlafaxine)
  • Glucophage XR (metformin)
  • Invega (paliperidone)
  • Nuelin SR (theophylline)
  • OxyContin (oxycodone)
  • Pristiq (desvenlafaxine)
  • Span-K (potassium chloride)
  • Urocit-K (potassium citrate)



Patient Counselling

When prescribing these controlled-release medicines, it is important to reassure patients that the active medicine will be released, even if remnants of the medicine can appear in their stools.

  • However, if the patient reports a lack of efficacy from their medication, further investigations may be warranted.



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