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[ citation needed ]	3600 mg	63–89%	1–4		37 min (PO); 8 min (IV)	5–6 hours
Aspirin (NSAID, non-opioid)	1⁄360[ citation needed ]	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[ citation needed ]	1600 mg	80–90%	8–12
Naproxen [10] (NSAID, non-opioid)	1⁄138	1380 mg	95%	12–24
Piroxicam (NSAID non-opioid)	1⁄120[ citation needed ]
Indomethacin (NSAID non-opioid)	1⁄64[ citation needed ]
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[ citation needed ]	16 mg IM (est.)		Nefopam: 3–8, Desmethylnefopam 10–15
Dextropropoxyphene [13]	1⁄20	130–200 mg
Codeine	3⁄20[ citation needed ]	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[ citation needed ]	~100 mg	75% (IR), 85–90% (ER)	6.0–8.8 [15] (M1)
Opium (oral)	1⁄10[ citation needed ]	~100 mg	~25% (morphine)	2.5–3.0 (morphine, codeine)
Tilidine	1⁄10[ citation needed ]	100 mg
Dihydrocodeine	1⁄5[ citation needed ]	50 mg	20%	4
Anileridine [16]	1⁄4	40 mg
Alphaprodine	1⁄6[ citation needed ]	40–60 mg
Tapentadol [17]	3⁄10	32 mg	32% (fasting)
Pethidine (meperidine)	1⁄3[ citation needed ]	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[ citation needed ]
AH-7921	4⁄5[ citation needed ]
Hydrocodone	1[ citation needed ]	10 mg	70% [20]	3.8–6 (Instant Release; PO)		10–30 min (Instant Release; PO)	4–6
Metopon	1[ citation needed ]	10 mg
Pentazocine lactate (IV) [21]	1	10 mg SC/IV/IM, 150 mg (PO)
SR-17018	4⁄5[ citation needed ]	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 parenteral 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[ citation needed ]
Nicomorphine	2–3[ citation needed ]	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[ citation needed ]	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[ citation needed ]	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[ citation needed ]	~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[ citation needed ]	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[ citation needed ]	1.5 mg		1.5–3
Levorphanol [34]	8	1.25 mg	70%	11–16	1:1
Desomorphine	8–10[ citation needed ]	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[ citation needed ]
Alfentanyl	10–25[ citation needed ]			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[ citation needed ]
Brifentanil	10-25[ citation needed ]
Acetylfentanyl	15[ citation needed ]
7-Hydroxymitragynine	17[ citation needed ]	~0.6 mg
Furanylfentanyl	20[ citation needed ]
Butyrfentanyl	25[ citation needed ]
Enadoline	25[ citation needed ]	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[ citation needed ]	160 μg
Phenomorphan	60–80[ citation needed ]	0.13–0.16 mg
N-Phenethylnordesomorphine	85[ citation needed ]
Phenaridine	50-100[ citation needed ]
Fentanyl	50–100[ citation needed ]	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[ citation needed ]	0.1 mg/100 μg
Acrylfentanyl	50-100+[ citation needed ]
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[ citation needed ]	77 μg
Etonitazepyne	180-190[ citation needed ]	55–60 μg
Protonitazepyne	180-190[ citation needed ]	55–60 μg
Remifentanil	100–200[ citation needed ]	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[ citation needed ]	50 μg
Ocfentanil	125–250[ citation needed ]	40–80 μg
Ro4-1539	240–480[ citation needed ]	20–40 μg
Isotonitazene	500[ citation needed ]	20 μg
Sufentanil	500–1,000[ citation needed ]	10–20 μg		4.4
BDPC	504[ citation needed ]	~20 μg
C-8813	591[ citation needed ]
4-Phenylfentanyl	800[ citation needed ]
Etonitazene	1000–1500[ citation needed ]	6.6–10 μg
3-Methylfentanyl	1000–1500[ citation needed ]
N-Desetylisotonitazene	1000–2000[ citation needed ]	5–10 μg
Etorphine	1,000–3,000[ citation needed ]	3.3–10 μg
Ohmefentanyl	6300[ citation needed ]
Acetorphine	8700[ citation needed ]	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[ citation needed ]
4-Carboethoxyohmefentanil	30,000[ citation needed ]
Ohmecarfentanil	30,000[ citation needed ]
R-30490	10,000-100,000[ citation needed ]
Lofentanil	10,000-100,000[ citation needed ]
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. Joishy 1999.
2. McPherson 2009, p. 5.
3. 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. "Dosing Guidelines for Acetaminophen and Selected NSAIDs" (PDF). Elsevier Health. Mosby. 1999. Retrieved 2022-11-22.
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12. Pharma Guide Pre-Work 3rd Edition
13. "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.
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21. "TALWIN (pentazocine lactate) injection, solution". DailyMed. National Institute of Health. Retrieved 2011-12-10.
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26. Tabla de equivalencia opiáceos
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32. Toronto Surgery 2014.
33. Walker 2001.
34. "Levorphanol". DrugBank Version: 3.0. DrugBank.
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36. "Buprenorphine / Naloxone Buccal Film (BUNAVAIL) C-III" (PDF). Pharmacy Benefits Management (PBM) Services. September 2014.
37. BUNAVAIL (buprenorphine and naloxone) buccal film, CIII [prescribing information online] . BioDelivery BioDelivery Sciences International, Inc. (BDSI), Raleigh, NC. Jun 2014.
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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
40. 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
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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43. King MA, Su W, Nielan CL, Chang AH, Schütz J, Schmidhammer H, Pasternak GW (17 January 2003). "14-Methoxymetopon, a very pote⁸nt μ-opioid receptor-selective analgesic with an unusual pharmacological profile". European Journal of Pharmacology. 459 (2): 205. doi:10.1016/s0014-2999(02)02821-2. PMID   12524147 . Retrieved 19 February 2024.

Bibliography

Books

• Cupp M (August 2012). "Equianalgesic Dosing of Opioids for Pain Management. PL Detail-Document #280801" (PDF). Pharmacist's Letter. Archived from the original (PDF) on 2015-02-13. Retrieved 2016-02-05.
• Joishy SK (1999). Palliative medicine secrets. Philadelphia: Hanley & Belfus. p. 97. ISBN   978-1-56053-304-7.
• McCaffery M, Pasero C (1999). Pain: Clinical Manual (2nd ed.). Mosby. ISBN   978-0-8151-5609-3., Extra information, including printable charts
• McPherson ML (2009). Demystifying Opioid Conversion Calculations: A Guide for Effective Dosing. Bethesda MD: American Society of Health-System Pharmacists. p. 5. ISBN   978-1-58528-297-5.

Articles

• Anderson R, Saiers JH, Abram S, Schlicht C (May 2001). "Accuracy in Equianalgesic Dosing". Journal of Pain and Symptom Management . 21 (5): 397–406. doi: 10.1016/S0885-3924(01)00271-8 . PMID   11369161.
• Natusch D (February 2012). "Equianalgesic doses of opioids – their use in clinical practice". British Journal of Pain. 6 (1): 43–46. doi: 10.1177/2049463712437628 . PMC   4590088 . PMID   26516465.
• Pereira J, Lawlor P, Vigano A, Dorgan M, Bruera E (August 2001). "Equianalgesic Dose Ratios for Opioids". Journal of Pain and Symptom Management . 22 (2): 672–687. doi: 10.1016/s0885-3924(01)00294-9 . PMID   11495714.
• Shaheen PE, Walsh D, Lasheen W, Davis MP, Lagman RL (September 2009). "Opioid equianalgesic tables: are they all equally dangerous?". Journal of Pain and Symptom Management. 38 (3): 409–417. doi: 10.1016/j.jpainsymman.2009.06.004 . ISSN   1873-6513. PMID   19735901.

Websites

• "Opioid Equianalgesic Table". Lecture Notes. Department of Surgery, University of Toronto. November 2014. Archived from the original on 26 February 2020. Retrieved 26 February 2020.
• Walker P (2001). "Issue 17. Morphine vs Hydromorphone vs Oxycodone vs The Patch". Palliative Care Tips: Info for Health Professionals. Palliative & End of Life Care (PEOLC), Alberta Health Services. Archived from the original on December 24, 2001.
• "Management of Opioid Therapy (OT) for Chronic Pain (2017)" (PDF). VA/DoD Clinical Practice Guidelines. Department of Veterans Affairs. p. 99. Retrieved 26 February 2020.
• Online opioid equianalgesia calculator Electronic calculator that includes logic for bidirectional and dose-dependent conversions