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An equianalgesic (or opioid) chart is a conversion chart that lists equivalent doses of analgesics (drugs used to relieve pain). Equianalgesic charts are used for calculation of an equivalent dose (a dose which would offer an equal amount of analgesia) between different analgesics.[1]


Equianalgesic tables are available in different formats, such as pocket-sized cards for ease of reference.[1] A frequently-seen format has the drug names in the left column, the route of administration in the center columns and any notes in the right column.[2]


There are several reasons for switching a patient to a different pain medication. These include practical considerations such as lower cost or unavailability of a drug at the patient's preferred pharmacy, or medical reasons such as lack of effectiveness of the current drug or to minimize adverse effects. Some patients request to be switched to a different narcotic due to stigma associated with a particular drug (e.g. a patient refusing methadone due to its association with opioid addiction treatment).[3] Equianalgesic charts are also used when calculating an equivalent dosage of the same drug, but with a different route of administration.


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.[4] For example, the narcotic levorphanol is 4–8 times stronger than morphine, but also has a much longer half-life. Simply switching the patient from 40 mg of morphine to 10 mg of levorphanol would be dangerous due to dose accumulation, and hence frequency of administration should also be taken into account.

There are other concerns about equianalgesic charts. Many charts derive their data from studies conducted on opioid-naïve patients. Patients with chronic (rather than acute) pain may respond to analgesia differently. Repeated administration of a medication is also different from single dosing, as many drugs have active metabolites that can build up in the body.[5] Patient variables such as sex, age, and organ function may also influence the effect of the drug on the system. These variables are rarely included in equianalgesic charts.[6]

Opioid-equivalency chart

Opioids are a class of compounds that elicit analgesic (pain killing) effects in humans and animals by binding to the μ-opioid receptor within the central nervous system. The following table lists commonly used opioid drugs and their relative potencies. Values for the potencies of opioids listed on this table are given as taken orally unless another route of administration is provided. As such, their bioavailabilities differ, and they may be more potent when taken intravenously. Methadone is different from most opioids considering its potency can vary depending on how long it is taken. Acute use, 1–3 days, yields a potency about 1.5× stronger than that of morphine and chronic use (7 days+) yields a potency about 2.5 to 5× that of morphine due to methadone being stored in fat tissue, thus giving higher serum levels with longer use.[citation needed] Similarly, the effect of tramadol increases after consecutive dosing due to the accumulation of its active metabolite and an increase of the oral bioavailability in chronic use, this effect becomes less significant again with even longer use as tolerance develops.[citation needed]

Opioid Equivalency Table
(morphine, PO)
Analgesic Strength
Equivalent dose
(10 mg oral morphine)
Bioavailability Half-life of active metabolites
Aspirin (non-opioid) 1360 3600 mg 100% 3.1–9
Ibuprofen[7] (NSAID, non-opioid) 1222 2220 mg 87-100% 1.3–3
Diflunisal (NSAID, non-opioid) 1160 1600 mg 80–90% 8–12
Naproxen[7] (NSAID, non-opioid) 1138 1380 mg 95% 12–24
Dextropropoxyphene[8] 113 to 120 130–200 mg
Codeine 110 180 mg (PO) ≈90% 2.5–3 (C6G 1.94;[9] morphine 2–3)
Tramadol 110 >200 mg 75% (IR), 85–90% (ER) 5.5–7 (≈9)[clarification needed]
Tapentadol 310[10] 32 mg 32% (fasting)
Tilidine 15 50 mg
Dihydrocodeine 15 50 mg 20% 4
Anileridine[11] 14 40 mg
Alphaprodine 1416 40–60 mg
Pethidine (meperidine hydrochloride) 13 30 mg SC/IM/IV, 300 mg PO 50–60% 3–5
Hydrocodone 1 10 mg ≥80% 3.8–6
Metopon 1 10 mg
Pentazocine lactate (IV) [12] 1 10 mg SC/IV/IM, 150 mg PO
Morphine (oral) (1) (10 mg) (30 mg PO) ≈25%
Oxycodone[13] 1.5 6.67 mg ≤87% 3–4.5
Morphine (IV/IM) 3 3.33 mg 100% 2–3
Clonitazene 3 3.33 mg
Methadone (acute) [14][15] 3–4 2.5–3.33 mg 40–90% 15–60
Diamorphine (heroin; IV/IM)[16] 4–5 2–2.5 mg 100% <0.6
Hydromorphone[17] 5 1.5 mg SC/IV/IM, 7.5 mg PO 62% 2–3
Oxymorphone[18] 7 10 mg PO, 1 mg IV 10% 7.25–9.43
Methadone (chronic) [15] 2.5–5 3.33  mg 40–90% 15–60
Levorphanol[19] 8 1.3 mg 70% 11–16
7-Hydroxymitragynine 17 ≈.6 mg
Buprenorphine[8] 40 0.4 mg 35–40% (SL) 20–70, mean 37
Fentanyl 50–100 0.1 mg (100 mcg) IM/IV 33% (SL); 92% (TD) 0.04 (IV); 7 (TD)
Sufentanil 500–1,000 10–20 μg 4.4
Bromadol[notes 1] 504 ≈ 20 µg
Etorphine[notes 1] 1,000–3,000 3.3–10 μg
Etonitazene[notes 1] 2,000 5.0 µg
Dihydroetorphine[notes 1] 1,000–12,000 20–40 µg
Carfentanil[notes 1][19] 10,000–100,000 0.1–1.0 μg 7.7
"Strength" is defined as analgesic potency relative to morphine.
Tolerance, sensitization, cross-tolerance, metabolism, and hyperalgesia may be complex factors in some individuals.
Interactions caused by polypharmacy, food and drink, and other factors, may potentiate or inhibit the effectiveness of certain analgesics as well as drastically alter their halflife.
Because some analgesics are prodrugs, individual variation in liver enzymes (e.g., cytochrome P450 enzyme CYP2D6) may result in significantly altered effects.

See also

  • Oripavine – for more on the comparative strength of oripavine derivatives


  1. 1.0 1.1 1.2 1.3 1.4 Because of their extreme potency, etorphine, carfentanil, and other similarly powerful opiates are only used for the sedation of large animals. Sufentanil is the strongest opioid used in human medicine.


  1. 1.0 1.1 Joishy, S. K. (1999). Palliative medicine secrets. Philadelphia PA: Hanley & Belfus. p. 97. ISBN 1-56053-304-8.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  2. McPherson, Mary Lynn M. (2000). Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. Bethesda MD: American Society of Health-System Pharmacists. p. 5. ISBN 1-58528-198-0.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  3. McPherson 2000, p. 3
  4. McPherson 2000, p. 4
  5. McPherson 2000, p. 8
  6. McPherson 2000, p. 9
  7. 7.0 7.1 http://www3.us.elsevierhealth.com/PAIN/pdf/Chart2a.pdf
  8. 8.0 8.1 "Ch. 4 Narcotics: Synthetic Narcotics: Dextropropoxyphene". Drugs of Abuse. Drug Enforcement Administration, U.S. Department of Justice. 2005.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  9. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  10. (PDF) https://www.nhms.org/sites/default/files/Pdfs/Opioid-Comparison-Chart-Prescriber-Letter-2012.pdf. Missing or empty |title= (help)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  11. "Anileridine". DrugBank Version: 3.0. DrugBank.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  12. "TALWIN (pentazocine lactate) injection, solution". DailyMed. National Institute of Health. Retrieved 2011-12-10.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  13. "Equianalgesic Conversion". GlobalRPH.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  14. http://www.psicofarmacos.info/images/graficos/Tabla4_opiaceos.JPG
  15. 15.0 15.1 Manfredonia JF (March 2005). "Prescribing methadone for pain management in end-of-life care". J Am Osteopath Assoc. 105 (3 Suppl 1): S18–21. PMID 18154194. |chapter= ignored (help)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  16. Reichle CW, Smith GM, Gravenstein JS, Macris SG, Beecher HK (April 1962). "Comparative analgesic potency of heroin and morphine in postoperative patients". J. Pharmacol. Exp. Ther. 136 (1): 43–6. PMID 14491157.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  17. http://www.palliative.org/PC/ClinicalInfo/PCareTips/MorphineVSHydromorphine.html (Log in required)
  18. "Equianalgesic Conversion". Global RPH.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  19. 19.0 19.1 "Levorphanol". DrugBank Version: 3.0. DrugBank.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>


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