The rectal route is an effective but frequently overlooked alternative to the oral route of medication administration. Though some individuals (patient or family members) object to this route, others may find it an acceptable alternative to parenteral medications when the oral route is unavailable. Temporary or chronic nausea and vomiting, changes in mental status, bowel obstruction and dysphagia are examples of conditions where the use of rectal medications may be appropriate.
The following are a few tips regarding the use of rectal meds (adapted from Pain: Clinical Manual, pages 204-206, McCaffery and Pasero, Mosby, 1999).
The effective starting dose of opioids by the rectal route is approximately equal to the oral dose. However, it has been recommended to reduce the starting dose by 25% to avoid possible increased sedation.
When titrating medications, bear in mind the onset of action may be slower than that of oral or parenteral routes.
Oral preparations of controlled-release medications can be used rectally, but must never be crushed or broken. When administering multiple tablets for a single dose, enclose them in a single gelatin capsule.
Dehydration or dry rectal mucosa can inhibit absorption. Lubricate the dosage with a small amount of water-soluble lubricant or water prior to insertion. Alternatively, 5-10ml of water can be instilled into the rectum with a syringe attached to a catheter before inserting the medication.
Avoid rectal irritation by use of lubrication, topical medications such as cortisone cream and gentle insertion techniques. Also, avoid use of solutions prepared in alcohol or glycol bases, as they can be very irritating to the mucosa.
Sigmoid colostomies (those that produce formed stool) can also be an effective alternative route for opioid administration. Insert the medication a finger’s depth into the stoma. Ask the patient to recline for 15-30 minutes to prevent expulsion or loss as a result of gravity.