|
|
For chronic opioid therapy, the oral or transdermal routes are preferred.
The transdermal route for fentanyl offers a 48- to 72-hour dosing interval,
allows a trial of fentanyl during sequential trials of opioid drugs, may
be associated with less constipation than oral drugs, and is preferred by
some patients. The use of the transdermal system is limited by the difficulties
involved in delivering high doses and the need for an alternative route
to provide supplemental doses for breakthrough pain. It also is not preferred
when rapid dose titration is needed for severe pain. Because drug delivery
is influenced by temperature, frequent fever spikes or the application of
external heat could lead to increased or unstable absorption from the transdermal
system.
The rectal formulation is generally considered only for short-term use.
An oral transmucosal formulation of fentanyl (oral transmucosal fentanyl
citrate or OTFC) has been approved for the treatment of cancer-related breakthrough
pain and is sometimes used for breakthrough pain of other types. This formulation
incorporates fentanyl into a lozenge that is sucked, allowing partial absorption
through the buccal mucosa. The formulation is effective and well tolerated,
and has an onset of effect faster than oral doses.
Long-term parenteral dosing can be accomplished by continuous intravenous
administration, if the patient has an indwelling venous access device, or
continuous subcutaneous administration.
A variety of techniques for intraspinal opioid delivery have been adapted
to long-term treatment, and properly selected patients can benefit greatly.
The clearest indication is intolerable somnolence or confusion in a patient
who is not experiencing adequate analgesia during systemic opioid treatment.
Continuous epidural infusion can be accomplished through either a percutaneous
or implanted epidural catheter. These approaches are generally used for
short-term therapy. Intrathecal infusion using a totally implanted pump
should be considered for patients with longer life expectancies.
The potential for intraspinal infusion has increased with the use of drug
combinations. The long-term administration of opioid, local anesthetic,
and clonidine is widely available. As new drugs are tested for intraspinal
therapy, the indications for the approach are likely to increase.
During long-term treatment, it may be necessary to switch routes of administration.
All such changes require careful attention to relative potency. It is generally
prudent to perform the switch in a gradual stepwise manner over a 2 to 3-day
period.
References
Hanks GWC, Cherny N, Fallon M. Opioid analgesic therapy. In: Doyle D, Hanks
GWC, Cherny NI, Calman K, eds. Oxford Textbook of Palliative Medicine, Third
Ed. Oxford: Oxford University Press, 2004, pp 316-341. |
 |
|
|
|
|