Do medications administered sublingually (under the tongue) in hospice patients bypass the gastrointestinal (GI) system?

Sublingual Medication Absorption in Hospice Patients

Medications administered sublingually in hospice patients do bypass the gastrointestinal system and are absorbed directly into the systemic circulation through the blood vessels under the tongue.

Mechanism of Sublingual Absorption

• Sublingual administration allows medications to enter the systemic circulation quickly and directly via venous drainage to the superior vena cava 1
• This route avoids first-pass metabolism in the liver, which occurs with orally ingested medications 2
• The sublingual mucosa is highly vascularized, allowing for rapid drug absorption directly into the bloodstream 3

Clinical Applications in Hospice Care

Medications Suitable for Sublingual Administration

• Lorazepam tablets can be used sublingually (off-label) for anxiety or agitation in hospice patients 4
• Alprazolam is available in sublingual tablet form and may be particularly advantageous for patients who cannot swallow 4
• Ondansetron is available in sublingual tablet form that may improve drug absorption compared with standard oral tablets 4

Advantages in Hospice Setting

• Provides rapid onset of action for symptom control
• Useful for patients who:
  • Have difficulty swallowing
  • Are unable to take oral medications
  • Need quick relief of breakthrough symptoms
  • Have nausea or vomiting that prevents oral medication use

Limitations of Sublingual Administration

• Small sublingual mucosa area limits absorption capacity 3
• Short residence time of medication under the tongue may affect complete absorption 3
• Not all medications are suitable for sublingual delivery due to:
  • Molecular size limitations
  • Poor lipid solubility
  • Potential for local irritation
  • Taste considerations

Comparison with Other Routes

• The preferred alternative routes for hospice patients who cannot take medications orally are rectal and subcutaneous 4
• The buccal mucosa (inside the cheek) is considerably less permeable than sublingual but may be better suited to sustained-delivery systems 5
• For medications requiring continuous administration, subcutaneous infusion is often preferred over repeated sublingual dosing 6

Important Clinical Considerations

• Medications must be specifically formulated or appropriate for sublingual use
• Crushing regular tablets for sublingual use is generally not recommended unless specifically indicated
• The ESMO guidelines note that "the buccal, sublingual, and nebulised routes of administration of morphine are not recommended because there is presently no evidence of clinical advantage over conventional routes" 4
• However, other opioids administered sublingually may be an alternative to subcutaneous injection 4

Best Practices for Sublingual Administration

• Ensure the patient's mouth is not excessively dry
• Place medication under the tongue and instruct patient not to swallow until dissolved
• Avoid eating, drinking, or smoking until medication is fully absorbed
• Monitor for effectiveness and adjust dosing as needed

Understanding the direct absorption mechanism of sublingual medications helps hospice providers select appropriate medications and routes of administration to provide optimal symptom control for patients who cannot take medications orally.