Equianalgesic Explained

An equianalgesic 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. Tables of this general type are also available for NSAIDs, benzodiazepines, depressants, stimulants, anticholinergics and others.

Format

Equianalgesic tables are available in different formats, such as pocket-sized cards for ease of reference. 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.

Purpose

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). Equianalgesic charts are also used when calculating an equivalent dosage of the same drug, but with a different route of administration.

Precautions

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. 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-naive 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. 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.

Opioid equivalency table

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 opioid and non-opioid analgesic drugs and their relative potencies. Values for the potencies represent opioids taken orally unless another route of administration is provided. As such, their bioavailabilities differ, and they may be more potent when taken intravenously.

Nonlinearities

This chart measures pain relief versus mass of medication. Not all medications have a fixed relationship on this scale. Methadone is different from most opioids because 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. 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.

Comparison to oral morphine
AnalgesicStrength
(relative)		Equivalent dose
(10 mg oral morphine)		BioavailabilityHalf-life of active metabolites
(hours)		Oral-to-parenteral ratioSpeed of onsetDuration
Paracetamol (non-opioid)3600 mg63–89%1–437 min (PO); 8 min (IV)5–6 hours
Aspirin (NSAID, non-opioid)3600 mg80–100%3.1–9
Ibuprofen[1] (NSAID, non-opioid)2220 mg87–100%1.3–3
Diflunisal (NSAID, non-opioid)1600 mg80–90%8–12
Naproxen (NSAID, non-opioid)1380 mg95%12–24
Piroxicam (NSAID non-opioid) (est.)
Indomethacin (NSAID non-opioid) (est.)
Diclofenac[2] (NSAID, non-opioid) (est.) (same as Codeine)100 mg (est.)50–60%1–4
Ketorolac[3] (NSAID, non-opioid) (est.)30 mg IV (est.)80–100%5–7
Nefopam (Centrally-acting non-opioid) (est.)16 mg IM (est.)Nefopam

3–8, Desmethylnefopam 10–15

Dextropropoxyphene[4] –130–200 mg
Codeine–100–120 mg (PO)~90%2.5–3 (C6G 1.94;[5] morphine 2–3)15–30 min (PO)4–6 hours
Tramadol~100 mg75% (IR), 85–90% (ER)6.0–8.8[6] (M1)
Opium (oral)~100 mg~25% (morphine)2.5–3.0 (morphine, codeine)
Tilidine100 mg
Dihydrocodeine50 mg20%4
Anileridine[7] 40 mg
Alphaprodine–40–60 mg
Tapentadol32 mg 32% (fasting)
Pethidine (meperidine)30 mg SC/IM/IV, 300 mg (PO)50–60%3–5
Benzylfentanyl
AH-7921
Hydrocodone110 mg70%[8] 3.8–6 (Instant Release; PO)10–30 min (Instant Release; PO)4–6
Metopon110 mg
Pentazocine lactate (IV)[9] 110 mg SC/IV/IM, 150 mg (PO)
Morphine (oral) 1 10 mg ~25%2–43:130 min (PO)3–6 hours
Oxycodone (oral)[10] 1.56.67 mg60-87%2–3 hours (Instant Release)(PO); 4.5 hours (Controlled Release)(PO)10–30 min (Instant Release)(PO); 1 hour (Controlled Release)(PO)3–6 hours (Instant Release)(PO); 10–12 hours (Controlled Release)(PO)[11]
Spiradoline1.5
Nicomorphine2–33.33–5 mg20%4
Oxycodone (IV)[12] 33.33 mg96%1.5–3 (IV)5 min (IV)2-4 hours
Morphine (IV/IM)33.33 mg100%2–3 3:1Instantaneously (from 5 to 15 sec; IV); 5–15 min (IM)3–7 hours
Clonitazene33.33 mg
Methadone (acute)[13] [14] 3–42.5–3.33 mg40–90%15–602:1
Methadone (chronic)2.5–52–4 mg40–90%15–602:1
Phenazocine4~2.5 mg
Diamorphine (Heroin; IV/IM)[15] 4–5 (iv, im) 2–2.5 (insufflated)[16] 2–2.5 mg100%<0.6 (morphine prodrug)[17] Instantaneously (from 5 to 15 sec; IV); 2 to 5 min (IM)3 to 7 hours
Dezocine4–61.6–2.5 mg97% (IM)2.2
Hydromorphone10 (SC, IV, IM)
3–3.75 (PO)		0.5-0.75 mg (SC, IV, IM)
2.5 mg (PO)		Orally: 30–35%, Intranasal: 52- 58% IV/IM: 100%62%2–35:1
Oxymorphone10 (SC, IV, IM)
3–4(PO)		3.33 mg (PO), 0.333 mg (IV,IM & Interlaminar)PO: 10%Buccal: 28% Sublingual:37.5%Intranasal: 43%IV, IM & IT: 100%7.25–9.4335 min (PO), Instantaneously (from 5 to 15 sec)(IV)6–8 hours orally2-6 hours parenteral
U-477007.51.5 mg1.5–3
Levorphanol[18] 81.25 mg70%11–161:1
Desomorphine (Krokodil)8–101–1.25 mg~100% (IV)2–3Instantaneously (from 5 to 15 sec)(IV); 2–5 min (IM)3–4 hours
N-Phenethylnormorphine8–14
Alfentanyl10–251.5 (90–111 minutes)Instantaneously (from 5 to 15 sec); 4× more rapid than fentanyl0.25 hr (15 min); up to 54 minutes until offset of effects
Trefentanil(10–25)+
Brifentanil(10–25)+
Acetylfentanyl15
7-Hydroxymitragynine17~0.6 mg
Furanylfentanyl20
Butyrfentanyl25
Enadoline2515 μg (threshold) and 0.160 mg/kg (dissociative effects)
Buprenorphine (SL)400.25 mg30% (SL);[19] ~100% (TD); 65% (buccal);[20] [21]

Notes and References

  1. Web site: Dosing Guidelines for Acetaminophen and Selected NSAIDs. Mosby. Elsevier Health. 2022-11-22. en. 1999.
  2. Web site: Diclofenac (Voltaren®) vs Naproxen (Aleve®, Naprosyn®) - eMedExpert.com . 2022-11-22 . www.emedexpert.com.
  3. Pharma Guide Pre-Work 3rd Edition
  4. Book: Ch. 4 Narcotics: Synthetic Narcotics: Dextropropoxyphene . http://www.dea.gov/pubs/abuse/4-narc.htm#Dextropropoxyphene . Drugs of Abuse . Drug Enforcement Administration, U.S. Department of Justice . 2005 . dead . https://web.archive.org/web/20061102144639/http://www.dea.gov/pubs/abuse/index.htm . 2006-11-02 .
  5. KuKanich B . Pharmacokinetics of acetaminophen, codeine, and the codeine metabolites morphine and codeine-6-glucuronide in healthy Greyhound dogs . J. Vet. Pharmacol. Ther. . 33 . 1 . 15–21 . February 2010 . 20444020 . 2867071 . 10.1111/j.1365-2885.2009.01098.x .
  6. Web site: ULTRAM® (tramadol hydrochloride) Tablets Full Prescribing Information. March 2008. US Food and Drug Administration. Ortho-McNeil Pharmaceutical, Inc.. 4. December 28, 2016. The mean terminal plasma elimination half-lives of racemic tramadol and racemic M1 are 6.3 ± 1.4 and 7.4 ± 1.4 hours, respectively. The plasma elimination half-life of racemic tramadol increased from approximately six hours to seven hours upon multiple dosing..
  7. Web site: Anileridine . DrugBank Version: 3.0 . DrugBank .
  8. Zacny JP, Gutierrez S . Within-subject comparison of the psychopharmacological profiles of oral hydrocodone and oxycodone combination products in non-drug-abusing volunteers . Drug Alcohol Depend . 101 . 1–2 . 107–14 . April 2009 . 19118954 . 10.1016/j.drugalcdep.2008.11.013 .
  9. Web site: TALWIN (pentazocine lactate) injection, solution . DailyMed . National Institute of Health . 2011-12-10 .
  10. Web site: Equianalgesic Conversion. GlobalRPH.
  11. Sunshine, A. . Olson, N. . Colon, A. . Rivera, J. . Kaiko, R.F. . Fitzmartin, R.D. . Reder, R.F. . Goldenheim, P.D. . Analgesic Efficacy of Controlled-Release Oxycodone in Postoperative Pain . Journal of Clinical Pharmacology . July 1996 . 36 . 7 . 595–603 . 10.1002/j.1552-4604.1996.tb04223.x . 8844441 . 35076787 .
  12. Silvasti . M . Rosenberg . P . Seppälä . T . Svartling . N . Pitkänen . M . Comparison of analgesic efficacy of oxycodone and morphine in postoperative intravenous patient-controlled analgesia . Acta Anaesthesiologica Scandinavica . May 1998 . 42 . 5 . 576–580 . 10.1111/j.1399-6576.1998.tb05169.x . 9605375 . 25763059 . 10 August 2022.
  13. http://www.psicofarmacos.info/images/graficos/Tabla4_opiaceos.JPG Tabla de equivalencia opiáceos
  14. Manfredonia JF . Prescribing methadone for pain management in end-of-life care . J Am Osteopath Assoc . 105 . 3 Suppl 1 . S18–21 . March 2005 . 18154194 . Table 2: Conversion Ratio of Oral Morphine to Methadone.
  15. Reichle CW, Smith GM, Gravenstein JS, Macris SG, Beecher HK . Comparative analgesic potency of heroin and morphine in postoperative patients . J. Pharmacol. Exp. Ther. . 136 . 1 . 43–6 . April 1962 . 14491157 .
  16. Cone . E. J. . Holicky . B. A. . Grant . T. M. . Darwin . W. D. . Goldberger . B. A. . October 1993 . Pharmacokinetics and pharmacodynamics of intranasal 'snorted' heroin . Journal of Analytical Toxicology . 17 . 6 . 327–337 . 10.1093/jat/17.6.327 . 0146-4760 . 8271778.
  17. Sawynok J . The therapeutic use of heroin: a review of the pharmacological literature . Canadian Journal of Physiology and Pharmacology . 64 . 1 . 1–6 . January 1986 . 2420426 . 10.1139/y86-001 .
  18. Web site: Levorphanol . DrugBank Version: 3.0 . DrugBank .
  19. Mendelson J, Upton RA, Everhart ET, Jacob P 3rd, Jones RT (1997). "Bioavailability of sublingual buprenorphine". Journal of Clinical Pharmacology. 37 (1): 31–7. doi:10.1177/009127009703700106. PMID 9048270
  20. Web site: Buprenorphine / Naloxone Buccal Film (BUNAVAIL) C-III. September 2014. Pharmacy Benefits Management (PBM) Services.
  21. Eriksen J, Jensen NH, Kamp-Jensen M, Bjarnø H, Friis P, Brewster D (1989). "The systemic availability of buprenorphine administered by nasal spray". J. Pharm. Pharmacol. 41 (11): 803–5. doi:10.1111/j.2042-7158.1989.tb06374.x
  22. Khanna, IK; Pillarisetti, S (2015). "Buprenorphine - an attractive opioid with underutilized potential in treatment of chronic pain". Journal of pain research. 8: 859–70. doi:10.2147/JPR.S85951. PMID 26672499
  23. Cote, J; Montgomery, L (July 2014). "Sublingual buprenorphine as an analgesic in chronic pain: a systematic review". Pain medicine (Malden, Mass.). 15 (7): 1171–8. doi:10.1111/pme.12386. PMID 24995716
  24. Ohmori. Satoshi. Morimoto. Yasunori. 2002. Dihydroetorphine: a potent analgesic: pharmacology, toxicology, pharmacokinetics, and clinical effects. CNS Drug Reviews. 8. 4. 391–404. 1080-563X. 12481194. 6741694. Dihydroetorphine (DHE) is one of the strongest analgesic opioid alkaloids known; it is 1000 to 12,000 times more potent than morphine. ...
    MOR is the most commonly used opioid analgesic for pain relief, and its oral daily dose (20 to 1000 mg) is relatively high (44). On the other hand, DHE produces rapid analgesic effects at an extremely low dose, 20 ìg sublingually in humans (60, 78). .... 10.1111/j.1527-3458.2002.tb00236.x.
  25. Web site: Carfentanil . DrugBank Version: 3.0 . DrugBank .
  26. King . Michael A . Su . Wendy . Nielan . Claire L . Chang . Albert H . Schütz . Johannes . Schmidhammer . Helmut . Pasternak . Gavril W . 14-Methoxymetopon, a very potent μ-opioid receptor-selective analgesic with an unusual pharmacological profile . European Journal of Pharmacology . 17 January 2003 . 459 . 2 . 205 . 10.1016/s0014-2999(02)02821-2 . 12524147 . 19 February 2024.
  27. BUNAVAIL (buprenorphine and naloxone) buccal film, CIII [prescribing information online]. BioDelivery BioDelivery Sciences International, Inc. (BDSI), Raleigh, NC. Jun 2014. 48% (INS)[21] | 20–70, mean 37|3:1|45 min|12–24 hours|-|N-Phenethyl-14-ethoxymetopon|60|160 μg||||||-|Phenomorphan|60–80|0.13–0.16 mg||||||-|N-Phenethylnordesomorphine|85|||||||-|Phenaridine|(50–100)−|||||||-| Fentanyl| 50–100| 0.1 mg (100 μg) IM/IV| 33% (SL); 92% (TD); 89% (INS); 50% (buc)| 0.04 (IV); 7 (TD)||5 min (TD/IV)|30–60 minutes (IV)|-|Metonitazene|100|0.1 mg/100 μg||||||-|Acrylfentanyl|(50–100+)|||||||-|Buprenorphine (Transdermal)[22] [23] |100–115|0.1 mg (100 μg)|30% (SL); ~100% (TD); 65% (buccal); 48% (INS)||3:1|45–60 minutes|12–24 hours|-|14-Cinnamoyloxycodeinone|177|77 μg||||||-|Etonitazepyne|180-190|55-60 μg||||||-|Protonitazepyne|180-190|55-60 μg||||||-|Remifentanil |100–200|50–100 μg||0.05 (3–6 min context-sensitive half-life; 7–18min elimination half-life) ||Instantaneously (from 5 to 15 sec)|15 minutes; rapid offset of effects necessitates continuous infusion for maintenance of anesthesia|-|Protonitazene|200|50 μg||||||-|Ocfentanil|125–250|40–80 μg||||||-|Ro4-1539|240–480|20-40 μg||||||-|Isotonitazene|500|20 μg||||||-| Sufentanil| 500–1,000| 10–20 μg| | 4.4||||-| BDPC| 504| ~20 μg| |||| |-|C-8813|591|||||||-|4-Phenylfentanyl|800|||||||-| Etonitazene| 1000-1500| 6,6-10 μg ||||||-|3-Methylfentanyl|1000-1500|||||||-|N-Desetylisotonitazene|1000-2000|5-10 μg||||||-| Etorphine| 1,000-3,000| 3.3–10 μg||||||-|Ohmefentanyl|6300|||||||-|Acetorphine|8700|1.33 μg||||||-| Dihydroetorphine[24] | 1,000–12,000| 0.83–10 μg (20–40 μg SL)| | ||||-| Carfentanil[25] | 10,000| 1.0 μg| | 7.7||||-|2-Fluorohmefentanil|18,000|||||||-|4-Carboethoxyohmefentanil|30,000|||||||-|Ohmecarfentanil|(30,000)|||||||-|R-30490|(10,000–100,000)−|||||||-|Lofentanil|(10,000–100,000)+|||||||-|14-Methoxymetopon (intraspinally)[26] |(1,000,000)|||||||-|colspan="9" style=" border: 1px solid #000000; text-align:center;" |PO: oral • IV: intravenous injection • IM: intramuscular injection • SC: subcutaneous injection • SL: sublingual • TD: transdermal
    "Strength" is defined as analgesic potency relative to oral morphine.
    Tolerance, sensitization, cross-tolerance, metabolism, and hyperalgesia may be complex factors in some individuals.
    Interactions with other drugs, food and drink, and other factors may increase or decrease the effect of certain analgesics and alter their half-life.
    Because some listed analgesics are prodrugs or have active metabolites, individual variation in liver enzymes (e.g., CYP2D6 enzyme) may result in significantly altered effects.    |}

    See also

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

    References

    Explanatory notes

    Citations

    Bibliography

    Books

    Articles

    • Anderson . Robert . Saiers . Joseph H . Abram . Stephen . Schlicht . Christian . Accuracy in Equianalgesic Dosing . . May 2001 . 21 . 5 . 397–406 . 10.1016/S0885-3924(01)00271-8. 11369161 . free. .
    • Natusch . Douglas . Equianalgesic doses of opioids – their use in clinical practice . British Journal of Pain . February 2012 . 6 . 1 . 43–46 . 10.1177/2049463712437628. 26516465 . 4590088 . free.
    • Pereira . Jose . Lawlor . Peter . Vigano . Antonio . Dorgan . Marlene . Bruera . Eduardo. Equianalgesic Dose Ratios for Opioids . . August 2001 . 22 . 2 . 672–687 . 10.1016/s0885-3924(01)00294-9 . free. 11495714. .
    • Shaheen . Philip E. . Walsh . Declan . Lasheen . Wael . Davis . Mellar P. . Lagman . Ruth L. . September 2009 . Opioid equianalgesic tables: are they all equally dangerous? . Journal of Pain and Symptom Management . 38 . 3 . 409–417 . 10.1016/j.jpainsymman.2009.06.004 . 1873-6513 . 19735901. free .

    Websites

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