Equianalgesic

 ( Anesthesia ) 

An equianalgesic chart is a conversion chart that lists equivalent doses of (drugs used to relieve pain). Equianalgesic charts are used for calculation of an equivalent dose (a dose which would offer an equal amount of Pain management) between different analgesics. Tables of this general type are also available for , , , , and others.

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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.

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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.

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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 pain (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.

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Opioid equivalency table 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 bioavailability differ, and they may be more potent when taken intravenously.

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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
Paracetamol (non-opioid)		3600 mg	63–89%	1–4		37 min (PO); 8 min (IV)	5–6 hours
Aspirin (NSAID, non-opioid)		3600 mg	80–100%	3.1–9
Ibuprofen (NSAID, non-opioid)		2220 mg	87–100%	1.3–3
Diflunisal (NSAID, non-opioid)		1600 mg	80–90%	8–12
Naproxen (NSAID, non-opioid)		1380 mg	95%	12–24
Indomethacin (NSAID non-opioid)
Diclofenac (NSAID, non-opioid)		100 mg (est.)	50–60%	1–4
KetorolacPharma Guide Pre-Work 3rd Edition (NSAID, non-opioid)		30 mg IM (est.)	80–100%	5–7
Nefopam (Centrally-acting non-opioid)		16 mg IM (est.)		Nefopam: 3–8, Desmethylnefopam 10–15
Piroxicam (2025). 9780721672786 . ISBN 9780721672786 (NSAID non-opioid)	3	6.66 mg				2–4 hours	40 hours
Dextropropoxyphene		130–200 mg
Codeine		100–120 mg (PO)	~90%	2.5–3 (C6G 1.94; morphine 2–3)		15–30 min (PO)	4–6 hours
Tramadol		~100 mg	75% (IR), 85–90% (ER)	6.0–8.8 (M1)
Opium (2025). 9789283201656, International Agency for Research on Cancer. . ISBN 9789283201656 (oral)		~100 mg	~25% (morphine)	2.5–3.0 (morphine, codeine)
Tilidine		100 mg	6% (parent drug), 99% (active metabolite)	nortilidine 3.3 (PO) & 4.9 IV, bisnortilidine 5 (PO) & 6.9 (IV)	2.2:1	10–15 minutes (oral) 25–50 minutes (peak analgesic effect)	3–4 hours
Dihydrocodeine (2025). 9780444510051 . ISBN 9780444510051		100 mg	20%	4
Anileridine		40 mg
Prodine		40–60 mg
Tapentadol		32 mg	32% (fasting)
Pethidine (meperidine) (2025). 9780323429740, Elsevier. . ISBN 9780323429740		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		25 mg (PO)		3.2–3.8 hours			±4 hours
Benzylfentanyl
AH-7921
SR-17018		10–12 mg	100% IV (Presumably) Unknown (researches are still being made)			5–10 seconds if used IV and 15-25 min Orally (PO)
Nalbuphine		10–11 mg	~33% (PO), 76% (SC), 81% (IM) (2025). 9780071354547, McGraw-Hill, Medical Publ. Division. . ISBN 9780071354547	3-6		3 minutes, 10 minutes (peak effect)	3–6 hours
Hydrocodone (2025). 9780323083409 . ISBN 9780323083409	1	10 mg	70%	3.8–6 (Instant Release; PO)		10–30 min (Instant Release; PO)	4–6
Pentazocine (IV)	1	10 mg SC/IV/IM, 150 mg (PO)
Morphine (oral)	1	10 mg	~25%	2–4	3:1	30 min (PO)	3–6 hours
Oxycodone (oral)	1.5	6.67 mg	(60–87 / ±75% PO) / 78.2% (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)
Spiradoline	1.5-7.0
Nicomorphine	2–3	3.33–5 mg	20%	4
Butorphanol	2.3	4.3 mg	~12% (PO), 25%-35% (SL), 70% (NAS) (2025). 9781437707212, W.B. Saunders. . ISBN 9781437707212	3 (IM/IV) 4.5-5.5 (NAS)	5.8:1	15 minutes	3–4 hours
Metopon	3	3.5 mg
Oxycodone (IV/IM) or other parental administrations apart from spinal administration	3–4	2.5–3.33 mg	(60–87 / ±75% PO) / 78.2% (IN) / 100% (IV/IM) or other parental administrations apart from spinal administration	1.5–3 (IV/IM)		5 min (IV)	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	2-3	3.33 mg
Methadone (acute) Tabla de equivalencia opiáceos Table 2: Conversion Ratio of Oral Morphine to Methadone.	3–4	2.5–3.33 mg	40–90%	15–60	2:1
Methadone (chronic)	2.5–5	2–4 mg	40–90%	15–60	2:1
Phenazocine	3.2-4.3 (1966). 9780080108957, Elsevier Ltd. . ISBN 9780080108957	~2.5 mg				15 min (IV); 30 minutes (IM); 30–60 minutes (oral)	3–5 hours
Heroin (Heroin; IV/IM) or other parental administrations apart from spinal administration	4–5 (IV,IM) 2–2.5 Insufflation	2–2.5 mg	100%	<0.6 (morphine prodrug)		Instantaneously (from 5 to 15 sec; IV); 2 to 5 min (IM)	3 to 7 hours (morphine prodrug)
6-MAM	6–7 (IV,IM)	1.25–1.6	100% (IV,IM)	<0.6 (morphine prodrug)	presumably 2:1	Instantaneously (from 5 to 15 sec; IV); 2 to 5 min (IM)	3 to 7 hours (morphine prodrug)
Dezocine	7.7-13	0.76-1.29 mg	97% (IM)	2.2	4–6 hours	5 min (IV); 5-15 min (IM/BUC); 6–8 hours (transdermal) (2025). 9780128012383, Elsevier Ltd. . ISBN 9780128012383
Hydromorphone	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	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	8	1.25 mg	70%	11–16	1:1
Desomorphine	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	0.1-0.4 mg		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
Brifentanil	10-25
Acetylfentanyl	15
7-Hydroxymitragynine	17	~0.6 mg
Butyrfentanyl	25
Enadoline	25	15 μg (threshold) and 0.160 mg/kg (dissociative effects)
Buprenorphine (SL)	40-80	0.25 mg	30% (SL); ~100% (Transdermal); 65% (BUC); BUNAVAIL (buprenorphine and naloxone) buccal film, CIII [prescribing information online]. BioDelivery BioDelivery Sciences International, Inc. (BDSI), Raleigh, NC. Jun 2014. 48% (INS)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	20–70, mean 37	3:1	45 min	12–24 hours
N-Phenethyl-14-ethoxymetopon	60	160 μg
Furanylfentanyl	50-100
Phenomorphan	60–80	0.13–0.16 mg
N-Phenethylnordesomorphine (1986). 9780306421303, Springer. . ISBN 9780306421303	85
Phenaridine	50-100
Fentanyl	50–100	0.1 mg (100 μg) IM/IV	33% (Sublingual); 92% (transdermal); 89% (intranasal); 50% (BUC)	0.04 (IV); 7 (transdermal)		5 min (transdermal/IV)	30–60 minutes (IV)
Metonitazene	100	0.1 mg/100 μg
Acrylfentanyl	50-100+
Remifentanil (2025). 9780128187883 . ISBN 9780128187883	100	100 μg	100% (IM/IV)	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
Parafluorofentanyl (2-Fluorofentanyl)	111
Buprenorphine (Transdermal)	100–115	0.1 mg (100 μg)	30% (SL); ~100% (Transdermal); 65% (BUC); 48% (INS)		3:1	45–60 minutes	12–24 hours
14-Cinnamoyloxycodeinone	177 (median potency) 101-310 (varied potencies among test subjects)	77 μg	2.8% (PO); 5.8% (SC)		250:7
Protonitazepyne	190-200	55–60 μg
Protonitazene	200	50 μg
Ocfentanil	200	40–80 μg
Ro4-1539	240–480	20–40 μg
14-Methoxymetopon	500 (IV)	20 μg
Isotonitazene	500	20 μg
Sufentanil	500–1,000 (2025). 9780721603346, Elsevier Inc.. . ISBN 9780721603346	10–20 μg	9% (PO); 52-59% (SL); 78% (BUC); 100% (IM/IV)	4.4	2:1	1-3 min (IV); 5 min (IN); 10 min (EPD); 6-15 min (SL)	30 min (IV); 40-50 min (SL) (2025). 9781890883539, American Association for Clinical Chemistry. . ISBN 9781890883539
BDPC	504	~20 μg
Orthofluorofentanyl	564	~17 μg
C-8813	591	~15 μg
4-Phenylfentanyl	800
Etonitazene	1,000–1,500	6.6–10 μg
3-Methylfentanyl	1,000 (3-methylfentanyl, (trans)-(+-)-isomer; 6,600 (3-methylfentanyl, (cis)-(-)-isomer)
N-Desetylisotonitazene	2,000	5–10 μg
Etonitazepyne	2,000	5 μg
Etorphine (2025). 9781437703108, Elsevier/Saunders. . ISBN 9781437703108	500–2,000	3.3–10 μg
Ohmefentanyl	6,300
Acetorphine	8,700	1.33 μg
Dihydroetorphine	12,000	0.83–10 μg (20–40 μg SL)
Carfentanil	10,000	1.0 μg		7.7
Lofentanil	10,000-11,000
4-Carboethoxyohmefentanil	30,000
Ohmecarfentanil	30,000
R-30490	10,000-100,000
14-Methoxymetopon	1,000,000 (intrathecal & supraspinal)	0.1 μg
PO: oral • BUC: buccal • SL: sublingual • TD: transdermal • IV: intravenous injection • IM: intramuscular injection • SC: subcutaneous injection • EPD: epidural injection "Strength" is defined as analgesic potency relative to oral morphine. Drug tolerance, sensitization, cross-tolerance, Drug metabolism, and hyperalgesia may be complex factors in some individuals. Drug interaction with Polypharmacy, Food, and other factors may increase or decrease the effect of certain analgesics and alter their half-life. Because some listed analgesics are or have active metabolites, individual variation in liver enzymes (e.g., CYP2D6 enzyme) may result in significantly altered effects.

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See also

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

Explanatory notes

Citations

Bibliography

: Books

• S. K. Joishy (1999). 9781560533047, Hanley & Belfus. ISBN 9781560533047
• (1999). 9780815156093, Mosby. . ISBN 9780815156093
  , Extra information, including printable charts
• Mary Lynn M. McPherson (2025). 9781585282975, American Society of Health-System Pharmacists. . ISBN 9781585282975

: Articles

: Websites

• Online opioid equianalgesia calculator Electronic calculator that includes logic for bidirectional and dose-dependent conversions

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