Equianalgesic

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.[1] 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.[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][3]

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

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.[5] 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.[6] 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.[7][3][8]

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.[citation needed]

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.[citation needed]

Comparison to oral morphine[a]
Analgesic Strength
(relative) 		Equivalent dose
(10 mg oral morphine)[b] 		Bioavailability Half-life of active metabolites
(hours) 		Oral-to-parenteral ratio Speed of onset Duration
Paracetamol (non-opioid) 1⁄360 3600 mg 63–89% 1–4 37 min (PO); 8 min (IV) 5–6 hours
Aspirin (NSAID, non-opioid) 1⁄360 3600 mg 80–100% 3.1–9
Ibuprofen[10] (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[10] (NSAID, non-opioid) 1⁄138 1380 mg 95% 12–24
Piroxicam (NSAID non-opioid) 1⁄120
Indomethacin (NSAID non-opioid) 1⁄64
Diclofenac[10][11] (NSAID, non-opioid) 1⁄10 100 mg (est.) 50–60% 1–4
Ketorolac[12] (NSAID, non-opioid) 1⁄3 30 mg IV (est.) 80–100% 5–7
Nefopam (Centrally-acting non-opioid) 5⁄8 16 mg IM (est.) Nefopam: 3–8, Desmethylnefopam 10–15
Dextropropoxyphene[13] 1⁄20 130–200 mg
Codeine 3⁄20 100–120 mg (PO) ~90% 2.5–3 (C6G 1.94;[14] morphine 2–3) 15–30 min (PO) 4–6 hours
Tramadol 1⁄10 ~100 mg 75% (IR), 85–90% (ER) 6.0–8.8[15] (M1)
Opium (oral) 1⁄10 ~100 mg ~25% (morphine) 2.5–3.0 (morphine, codeine)
Tilidine 1⁄10 100 mg
Dihydrocodeine 1⁄5 50 mg 20% 4
Anileridine[16] 1⁄4 40 mg
Alphaprodine 1⁄6 40–60 mg
Tapentadol[17] 3⁄10 32 mg 32% (fasting)
Pethidine (meperidine) 1⁄3 30 mg SC/IV/IM

300 mg (PO)

50–60% Orally, 100% SC/IV/IM 3–5 5–15 sec if IV, 15–25 min if orally
Dipipanone[18][19] 2⁄5 25 mg (PO) 3.2–3.8 hours ±4 hours
Benzylfentanyl 1⁄2
AH-7921 4⁄5
Hydrocodone 1 10 mg 70%[20] 3.8–6 (Instant Release; PO) 10–30 min (Instant Release; PO) 4–6
Metopon 1 10 mg
Pentazocine lactate (IV)[21] 1 10 mg SC/IV/IM, 150 mg (PO)
SR-17018 4⁄5 10–12 mg 100% IV (Presumably)

Unknown (researches are still being made)

5–10 seconds if used IV and 15-25 min Orally (PO)
Morphine (oral) 1 10 mg ~25% 2–4 3:1 30 min (PO) 3–6 hours
Oxycodone (oral)[22] 1.5 6.67 mg (60–87 / ±75% PO) / 78.2%[23] (IN) / 100%

(IV/IM) or other parental administrations apart from spinal administration

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)[24]
Spiradoline 1.5
Nicomorphine 2–3 3.33–5 mg 20% 4
Oxycodone (IV/IM) or other parental administrations apart from spinal administration[25] 3–4 2.5–3.33 mg (60–87 / ±75% PO) / 78.2%[23] (IN) / 100%

(IV/IM) or other parental administrations apart from spinal administration

1.5–3 (IV/IM) 5 min (IV)[25] 2–4 hours
Morphine (IV/IM) or other parental administrations apart from spinal administration 3–4 2.5–3.33 mg 100% 3–4 3:1/4:1 Instantaneously (from 5 to 15 sec; IV); 5–15 min (IM) 3–7 hours
Clonitazene 3 3.33 mg
Methadone (acute)[26][27] 3–4 2.5–3.33 mg 40–90% 15–60 2:1
Methadone (chronic)[27] 2.5–5 2–4 mg 40–90% 15–60 2:1
Phenazocine 4 ~2.5 mg
Diamorphine (Heroin;

IV/IM) or other parental administrations apart from spinal administration[28]

4–5 (IV,IM)

2–2.5 (insufflated)[29]

2–2.5 mg 100% <0.6 (morphine prodrug)[30] Instantaneously (from 5 to 15 sec; IV); 2 to 5 min (IM) 3 to 7 hours

(morphine prodrug)[30]

Dezocine 4–6 1.6–2.5 mg 97% (IM) 2.2
6-MAM[31] 6–7

(IV,IM)

1.25–1.6 100% (IV,IM) <0.6 (morphine prodrug)[30] presumably 2:1 Instantaneously (from 5 to 15 sec; IV); 2 to 5 min (IM) 3 to 7 hours

(morphine prodrug)[30]

Hydromorphone[32][33][17] 10 (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%

2–3 5:1
Oxymorphone[22] 10 (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%

7.25–9.43 35 min (PO), Instantaneously (from 5 to 15 sec)(IV) 6–8 hours orally

2–6 hours parenteral

U-47700 7.5 1.5 mg 1.5–3
Levorphanol[34] 8 1.25 mg 70% 11–16 1:1
Desomorphine (Krokodil) 8–10 1–1.25 mg ~100% (IV) 2–3 Instantaneously (from 5 to 15 sec)(IV); 2–5 min (IM) 3–4 hours
N-Phenethylnormorphine 8–14
Alfentanyl 10–25 1.5 (90–111 minutes) Instantaneously (from 5 to 15 sec); 4× more rapid than fentanyl 0.25 hr (15 min); up to 54 minutes until offset of effects
Trefentanil 10-25
Brifentanil 10-25
Acetylfentanyl 15
7-Hydroxymitragynine 17 ~0.6 mg
Furanylfentanyl 20
Butyrfentanyl 25
Enadoline 25 15 μg (threshold) and 0.160 mg/kg (dissociative effects)
Buprenorphine (SL)[13] 40 0.25 mg 30% (SL);[35] ~100% (TD); 65% (buccal);[36][37] 48% (INS)[38] 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)[39][40] 100–115 0.1 mg (100 μg) 30% (SL);[35] ~100% (TD); 65% (buccal);[36][37] 48% (INS)[38] 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; 7–18 min 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[41] 1,000–12,000 0.83–10 μg (20–40 μg SL)
Carfentanil[42] 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)[43] 1,000,000
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

  1. ^ Approximate. There is a wide range of values in controlled trials.[9]
  2. ^ 10 mg oral morphine is equivalent to n mg analgesic drug x, e.g. 10 mg morphine is equivalent to 3600 mg paracetamol or 1.5 mg hydromorphone

Citations

  1. ^ a b Joishy 1999.
  2. ^ McPherson 2009, p. 5.
  3. ^ a b Natusch 2012.
  4. ^ McPherson 2009, p. 3.
  5. ^ McPherson 2009, p. 4.
  6. ^ McPherson 2009, p. 8.
  7. ^ McPherson 2009, p. 9.
  8. ^ Anderson et al 2001.
  9. ^ Pereira et al 2001.
  10. ^ a b c "Dosing Guidelines for Acetaminophen and Selected NSAIDs" (PDF). Elsevier Health. Mosby. 1999. Retrieved 2022-11-22.
  11. ^ "Diclofenac (Voltaren®) vs Naproxen (Aleve®, Naprosyn®) - eMedExpert.com". www.emedexpert.com. Retrieved 2022-11-22.
  12. ^ Pharma Guide Pre-Work 3rd Edition
  13. ^ a b "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.
  14. ^ 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. doi:10.1111/j.1365-2885.2009.01098.x. PMC 2867071. PMID 20444020.
  15. ^ "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.
  16. ^ "Anileridine". DrugBank Version: 3.0. DrugBank.
  17. ^ a b Cupp 2012.
  18. ^ "Dipipanone", Wikipedia, 2024-06-14, retrieved 2024-10-19
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  26. ^ Tabla de equivalencia opiáceos
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  32. ^ Toronto Surgery 2014.
  33. ^ Walker 2001.
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  37. ^ a b BUNAVAIL (buprenorphine and naloxone) buccal film, CIII [prescribing information online]. BioDelivery BioDelivery Sciences International, Inc. (BDSI), Raleigh, NC. Jun 2014.
  38. ^ a b 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
  39. ^ 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
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  41. ^ Ohmori S, Morimoto Y (2002). "Dihydroetorphine: a potent analgesic: pharmacology, toxicology, pharmacokinetics, and clinical effects". CNS Drug Reviews. 8 (4): 391–404. doi:10.1111/j.1527-3458.2002.tb00236.x. ISSN 1080-563X. PMC 6741694. 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). ...
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