Codeine |
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Tramadol |
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Morphine |
In patients with renal dysfunction, morphine-6-glucuronide, an active metabolite of morphine, can accumulate to toxic levels
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Oxycodone, hydromorphone, hydrocodone |
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Fentanyl |
Before starting fentanyl, ensure the patient has been fully opioid tolerant during the previous 2 wk (total dose of at least 60–90 mg/d morphine equivalence) on a scheduled dose (at least twice daily for CR or 4 times daily for IR) Do not switch from codeine to fentanyl regardless of the codeine dose, as some patients taking codeine might have little or no opioid tolerance Maintain the starting dose for at least 6 d and use extra caution with patients at higher risk of overdose (eg, the elderly, those taking benzodiazepines) Advise the patient as follows:
-Be alert for signs of overdose; if detected, remove the patch and seek medical attention -Apply the patches as prescribed; do not apply more than 1 patch at a time -Avoid heat sources such as heating pads -Enforce patch-for-patch exchange at pharmacy to reduce diversion
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Methadone |
Use methadone to treat pain only if you hold a written Health Canada exemption Titration is hazardous because of its very long half-life, which leads to bioaccumulation
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Meperidine |
Not recommended for use in CNCP owing to poor bioavailability and inferior effectiveness to codeine Normeperidine, a metabolite of meperidine, can accumulate with frequent use causing seizures and delirium
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Acetaminophen-opioid combinations |
Use with caution to not exceed maximum dose of 3.2 g/d of acetaminophen for adults (10 tablets/d of opioid-acetaminophen combinations) No more than 8 tablets/d for tramadol-acetaminophen combinations Warn alcohol drinkers to not mix alcohol with acetaminophen
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CR formulations |
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Tapentadol |
Contraindicated in those with severe hepatic or renal dysfunction, or taking monoamine oxidase inhibitors Small risk of seizure seen in postmarketing reports
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Parenteral opioids |
Parenteral opioids are not recommended for treatment of CNCP owing to increased risk of overdose, abuse, addiction, and infection
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