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The
figure below is an example of a repeated dose study that uses
rescue analgesic to make a placebo control group possible. Stambaugh
and Drew (1988) compared the effects of adding either ibuprofen
or placebo to an ad lib opiod regimen in patients with metastatic
bone pain. They conducted a 14-day study in hospitalized cancer
patients whose metastatic bone pain required at least four daily
doses of an oxycodone/acetaminophen (oxy/APAP) combination.
Strong parenteral opioids were also given for severe breakthrough
pain, but patients requiring more than one injection daily were
dropped from the study. The protocol is outlined below.
Days
1-7:
- No
intervention;
- Daily
dose of oxy/APAP monitored; and
- Patients
assessed pain intensity and relief once a day.
Days
8-14
- One-half
of patients received ibuprofen 600 mg po four times daily;
other half received placebo.
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Click
on image to enlarge
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Figure
4.1: Repeated Dose Trial of Ibuprofen vs.
Placebo with Rescue Analgsic for Metastatic
Bone Pain
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top panel of Figure 4.1 shows that pain relief was better
with ibuprofen than placebo, and the bottom panel shows
that the ibuprofen-treated group reduced their oxy/APAP
consumption relative to the placebo group.
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This example illustrates how use of the background or rescue
analgesic becomes an important outcome measure. Similar strategies
have been used to study the analgesic effects of sustained-release
morphine in cancer patients (Portenoy,
1991) and
many types of
interventions
in postoperative pain (VadeBoncouer
et al., 1989; Lehmann et al.,
1991). In these designs, the rescue analgesic may be given
by any of a variety of routes, including oral, intramuscular,
or intravenous (commonly by patient-controlled analgesia devices).
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