Pain and Chemical Dependency: For Professionals
As titration of an opioid dose occurs, some patients will experience the
onset of intolerable and unmanageable side effects. If this is observed,
the patient should be labeled poorly responsive to the specific drug and
route of administration. Poor responsiveness cannot be determined unless
the dose has been increased to treatment-limiting side effects. If a patient
is poorly responsive, an alternative analgesic strategy is needed (Table).
Table: Therapeutic Strategies when A Patient Is Poorly Responsive to An Opioid Regimen (.pdf)
Studies of medically ill patients indicate that the need for a dose increase
usually can be explained by a change in disease. Although tolerance to analgesic
effects may require dose escalation in some situations, tolerance cannot
be invoked as the “driver” if a change in disease is observed.
These observations imply that
- concern about tolerance should not impede the use of an opioid,
- clinically significant tolerance may or may not occur,
- whether dose escalation is needed because of clinical change
or tolerance, analgesia usually can be recaptured through dose escalation, and
- 4because the need for dose escalation cannot be immediately ascribed
to tolerance, worsening pain in a patient receiving a stable dose of opioids
must be reassessed to rule out a new process, such as disease progression or
increasing psychological distress or delirium.
The decision to offer a so-called “rescue dose” during long-term
opioid therapy must be made on a case-by-case basis. A rescue is a short-acting
drug administered “as needed” for breakthrough pain. This strategy
is conventional practice in cancer pain management. When treating a patient
with nonmalignant pain, the clinician should consider the approach is the
pain fluctuates and the patient is likely to tolerate the extra doses and
use them in a consistently responsible way.
Based on clinical experience, the size of the most effective rescue dose
usually is selected to be equivalent to 5 to 15% of the total daily opioid
dose. The lower end of this range is used if the patient is medically frail
or has moderately intense breakthrough pain. The upper end is used if the
breakthrough pains are anticipated to be severe and the risk is not excessive,
considering factors such as advanced age or major organ failure that predispose
to opioid toxicity. Oral transmucosal fentanyl (OTFC), a formulation of
fentanyl in a lozenge, is an exception. In several clinical trials, there
was no relationship between the effective dose of OTFC and the total daily
opioid dose. Therefore, OTFC should be initiated at one of the lower available
dosages (200 mg or 400 mg) and the dose should be rapidly titrated until
the appropriate dose is identified. Oral rescue doses typically are offered
up to every 1 to 2 hr as needed, and parenteral rescue doses can be offered
up to every 15 to 30 min.
The severity of the pain should determine the rate of dose titration. Patients
with very severe pain can be managed by repeated parenteral dosing every
15 to 30 min until pain is partially relieved. Aggressive dose titration
is rarely indicated in patients with stable chronic pain syndromes, who
are treated in the outpatient setting.
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. |
|
|
