Format[ edit ] Equianalgesic tables are available in different formats, such as pocket-sized cards for ease of reference. Some patients request to be switched to a different narcotic due to stigma associated with a particular drug e. Precautions[ edit ] An equianalgesic chart can be a useful tool, but the user must take care to correct for all relevant variables such as route of administration, cross tolerance , half-life and the bioavailability of a drug. There are other concerns about equianalgesic charts. Patients with chronic rather than acute pain may respond to analgesia differently.
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Load an Example About This Calculator Equianalgesic conversions used in this calculator are based on the American Pain Society guidelines and critical review papers regarding equianalgesic dosing.
There is an overall lack of data regarding most equianalgesic conversions, and there is a significant degree of interpatient variability. For this reason, reasonable clinical judgment, breakthrough rescue opioid regimens, and dose titration are of paramount importance.
While these equianalgesic tables are current the "best" solution, their limitations should be emphasized: Single-dose studies: Early studies determining equianalgesia were based on single doses, not chronic administation. Bidirectional conversions: When converting between certain opioids, the direction of conversion eg, morphine to hydromorphone versus hydromorphone to morphine will produce a different conversion ratio.
These bidirectional differences are not captured in a traditional equianalgesic table. In the case of converting morphine to methadone, methadone has a relative potency of at lower morphine doses, but becomes much more potent in patients converting from very high morphine doses. Equianalgesic Discrepancies: There are significant discrepancies in equianalgesic dosing tables, with even FDA-approved drug labels not demonstrating agreement.
Patient-specific factors: No equianalgesic table is able to take into account patient-specific factors -- primarily hepatic function, renal function, and age. Opioid metabolism and excretion do differ among the opioids; therefore, alterations in drug disposition will alter the relative potencies of different opioids.
Cross-Tolerance Reduction When switching between opioids, equianalgesic conversions may overestimate the potency of the new opioid due to incomplete cross-tolerance. Incomplete cross-tolerance can occur due to variability in opioid binding. There is no evidence-based recommendation for an appropriate reduction.
In an inpatient setting, rescue doses can be provided IV every minutes. Oral rescue doses can be offered as needed over the normal dosing interval of the drug typically every 4 hours. As stated above, because equianalgesic tables are inherently inaccurate, the availability of breakthrough doses is paramount. Opioid Dose Titration Because equianalgesic tables are inherently inaccurate, dose titration to optimal effect is essential.
Because transdermal fentanyl has a delayed onset and onset of peak activity, consider titrating every 3 days. Practice guidelines for transdermal opioids in malignant pain.
PMID An alternative algorithm for dosing transdermal fentanyl for cancer-related pain. Oncology Williston Park. American Pain Society. Principles of analgesic use in the treatment of acute pain and cancer pain. Accuracy in equianalgesic dosing. J Pain Symptom Manage. Equianalgesic dose ratios for opioids. Opioid conversions in acute care. Ann Pharmacother. Opioid rotation: the science and the limitations of the equianalgesic dose table.
Clinical guidelines for the use of chronic opioid therapy in chronic noncancer pain. J Pain. Opioid equianalgesic tables: are they all equally dangerous? Levy MH. Pharmacologic treatment of cancer pain.
N Engl J Med. Cherny NI. Opioid analgesics: comparative features and prescribing guidelines. Management of cancer pain: adults. Agency for Health Care Policy and Research.
Am J Hosp Pharm.
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