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. Tables of this general type are also available for NSAIDs, benzodiazepines, depressants, stimulants, anticholinergics and others as well.
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.
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.
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-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. 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 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. 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.
|Opioid Equivalency Table
(10 mg oral morphine)
|Bioavailability||Half-life of active metabolites
|Oral-to-parenteral ratio||Speed of onset||Duration||Chemical / structural class|
|Paracetamol (non-opioid)||1⁄360||3600 mg||63–89%||1–4|
|Aspirin (NSAID, non-opioid)||1⁄360||3600 mg||80–100%||3.1–9|
|Ibuprofen (NSAID, non-opioid)||1⁄222||2220 mg||87–100%||1.3–3|
|Diflunisal (NSAID, non-opioid)||1⁄160||1600 mg||80–90%||8–12|
|Naproxen (NSAID, non-opioid)||1⁄138||1380 mg||95%||12–24|
|Diclofenac (NSAID, non-opioid)||1⁄14 (est.)||160 mg (est.)||50–60%||1–4|
|Nefopam (Centrally-acting non-opioid)||5⁄8 (est.)|
|Indomethacin (NSAID non-opioid)||1⁄64 (est.)|
|Piroxicam (NSAID non-opioid)||1⁄120 (est.)|
|Dextropropoxyphene||1⁄13– 1⁄20||130–200 mg|
|Codeine||1⁄10– 3⁄20||67–100 mg PO||~90%||2.5–3 (C6G 1.94; morphine 2–3)|
|Tramadol||1⁄10||>200 mg||75% (IR), 85–90% (ER)||6.0–8.8 (M1)|
|Opium (oral)||1⁄10||~100 mg||~35%||2.5–3.0 (morphine, codeine)|
|Alphaprodine||1⁄4– 1⁄6||40–60 mg|
|Tapentadol||3⁄10||32 mg||32% (fasting)|
|Pethidine (meperidine)||1⁄3||30 mg SC/IM/IV, 300 mg PO||50–60%||3–5|
|Pentazocine lactate (IV)||1||10 mg SC/IV/IM, 150 mg PO|
|Morphine (oral)||1||10 mg||~25%|
|Morphine (IV/IM)||3||3.33 mg||100%||2–3|
|Methadone (acute)||3–4||2.5–3.33 mg||40–90%||15–60|
|Methadone (chronic)||2.5–5||3.33 mg||40–90%||15–60|
|Diamorphine (heroin; IV/IM)||4–5||2–2.5 mg||100%||<0.6|
|Dezocine||4–6||1.6–2.5 mg||97% (IM)||2.2|
|Hydromorphone||4||1.5 mg SC/IV/IM, 7.5 mg PO||62%||2–3|
|Oxymorphone||3–7||10 mg PO, 1 mg IV||10%–||7.25–9.43|
|Desomorphine (Krokodil)||8–10||1 mg–1.25 mg||~100% (IV)||2–3|
|Buprenorphine||40||0.4 mg||35–40% (SL)||20–70, mean 37|
|Fentanyl||50–100||0.1 mg (100 µg) IM/IV||33% (SL); 92% (TD)||0.04 (IV); 7 (TD)|
|Remifentanil||100–200||50 µg–100 µg|
|Dihydroetorphine||1,000–12,000||0.83–10 µg (20–40 µg SL)|
|Ethylmorphine (Dionine, Codethylene)||20%|
|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.
- Oripavine – for more on the comparative strength of oripavine derivatives
- Joishy, S. K. (1999). Palliative medicine secrets. Philadelphia PA: Hanley & Belfus. p. 97. ISBN 1-56053-304-8.
- 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.
- McPherson 2000, p. 3
- McPherson 2000, p. 4
- McPherson 2000, p. 8
- McPherson 2000, p. 9
- "Dosing Guidelines for Acetaminophen and Selected NSAIDs" (PDF). www3.us.elsevierhealth.com.
- "Ch. 4 Narcotics: Synthetic Narcotics: Dextropropoxyphene". Drugs of Abuse. Drug Enforcement Administration, U.S. Department of Justice. 2005. Archived from the original on 2006-11-02.
- KuKanich B (February 2010). "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. PMC . PMID 20444020. doi:10.1111/j.1365-2885.2009.01098.x.
- "ULTRAM® (tramadol hydrochloride) Tablets Full Prescribing Information" (PDF). US Food and Drug Administration. Ortho-McNeil Pharmaceutical, Inc. March 2008. p. 4. Retrieved 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.
- "Anileridine". DrugBank Version: 3.0. DrugBank.
- "Equianalgesic Dosing of Opioids for Pain Management" (PDF). August 2012.
- "TALWIN (pentazocine lactate) injection, solution". DailyMed. National Institute of Health. Retrieved 2011-12-10.
- "Equianalgesic Conversion". GlobalRPH.
- Tabla de equivalencia opiáceos
- 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. Table 2: Conversion Ratio of Oral Morphine to Methadone.
- 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.
- Paul Walker. "MORPHINE vs HYDROMORPHINE vs OXYCODONE vs THE PATCH". Archived from the original on December 24, 2001.
- "Levorphanol". DrugBank Version: 3.0. DrugBank.
- Ohmori, Satoshi; Morimoto, Yasunori (2002). "Dihydroetorphine: a potent analgesic: pharmacology, toxicology, pharmacokinetics, and clinical effects". CNS drug reviews. 8 (4): 391–404. ISSN 1080-563X. PMID 12481194.
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). ...
- "Carfentanil". DrugBank Version: 3.0. DrugBank.
- Equianalgesic Charts
- American Pain Society Guidelines
- Clinical Practice Guideline for the Management of Opioid Therapy for Chronic Pain
- Online opioid equianalgesia calculator Electronic calculator that includes logic for bidirectional and dose-dependent conversions
- Opioid equianalgesic tables: are they all equally dangerous?