Most potent opioids

FENTAMAS

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This table is from wiki Equianalgesic page. It is a bit inaccurate and far from being complete list, but I'll later add more interesting compounds.


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)
Paracetamol (non-opioid)1⁄3603600 mg63–89%1–437 min (PO); 8 min (IV)5–6 hours
Aspirin (NSAID, non-opioid)1⁄3603600 mg80–100%3.1–9
Ibuprofen[10] (NSAID, non-opioid)1⁄2222220 mg87–100%1.3–3
Diflunisal (NSAID, non-opioid)1⁄1601600 mg80–90%8–12
Naproxen[10] (NSAID, non-opioid)1⁄1381380 mg95%12–24
Piroxicam (NSAID non-opioid)1⁄120 (est.)
Indomethacin (NSAID non-opioid)1⁄64 (est.)
Diclofenac[10][11] (NSAID, non-opioid)1⁄10 (est.) (same as Codeine)100 mg (est.)50–60%1–4
Ketorolac[12] (NSAID, non-opioid)1⁄3 (est.)30 mg IV (est.)80–100%5–7
Nefopam (Centrally-acting non-opioid)5⁄8 (est.)16 mg IM (est.)Nefopam: 3–8, Desmethylnefopam 10–15
Dextropropoxyphene[13]1⁄13–1⁄20130–200 mg
Codeine1⁄10–3⁄20100–120 mg (PO)~90%2.5–3 (C6G 1.94;[14] morphine 2–3)15–30 min (PO)4–6 hours
Tramadol1⁄10~100 mg75% (IR), 85–90% (ER)6.0–8.8[15] (M1)
Opium (oral)1⁄10~100 mg~25% (morphine)2.5–3.0 (morphine, codeine)
Tilidine1⁄10100 mg
Dihydrocodeine1⁄550 mg20%4
Anileridine[16]1⁄440 mg
Alphaprodine1⁄4–1⁄640–60 mg
Tapentadol[17]3⁄1032 mg32% (fasting)
Pethidine (meperidine)1⁄330 mg SC/IM/IV, 300 mg (PO)50–60%3–5
Benzylfentanyl1⁄2
AH-79214⁄5
Hydrocodone110 mg70%[18]3.8–6 (Instant Release; PO)10–30 min (Instant Release; PO)4–6
Metopon110 mg
Pentazocine lactate (IV)[19]110 mg SC/IV/IM, 150 mg (PO)
Morphine (oral) 1 10 mg ~25%2–43:130 min (PO)3–6 hours
Oxycodone (oral)[20]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)[21]
Spiradoline1.5
Nicomorphine2–33.33–5 mg20%4
Oxycodone (IV)[22]33.33 mg96%1.5–3 (IV)5 min (IV)[22]2-4 hours
Morphine (IV/IM)33.33 mg100%2–33:1Instantaneously (from 5 to 15 sec; IV); 5–15 min (IM)3–7 hours
Clonitazene33.33 mg
Methadone (acute)[23][24]3–42.5–3.33 mg40–90%15–602:1
Methadone (chronic)[24]2.5–52–4 mg40–90%15–602:1
Phenazocine4~2.5 mg
Diamorphine (Heroin; IV/IM)[25]4–5 (iv, im) 2–2.5 (insufflated)[26]2–2.5 mg100%<0.6 (morphine prodrug)[27]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
Hydromorphone[28][29][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%
2–35:1
Oxymorphone[20]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%
7.25–9.4335 min (PO), Instantaneously (from 5 to 15 sec)(IV)6–8 hours orally
2-6 hours parenteral
U-477007.51.5 mg1.5–3
Levorphanol[30]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)[13]400.25 mg30% (SL);[31] ~100% (TD); 65% (buccal);[32][33] 48% (INS)[34]20–70, mean 373:145 min12–24 hours
N-Phenethyl-14-ethoxymetopon60160 μg
Phenomorphan60–800.13–0.16 mg
N-Phenethylnordesomorphine85
Phenaridine(50–100)−
Fentanyl50–1000.1 mg (100 μg) IM/IV33% (SL); 92% (TD); 89% (INS); 50% (buc)0.04 (IV); 7 (TD)5 min (TD/IV)30–60 minutes (IV)
Metonitazene1000.1 mg/100 μg
Acrylfentanyl(50–100+)
Buprenorphine (Transdermal)[35][36]100–1150.1 mg (100 μg)30% (SL);[31] ~100% (TD); 65% (buccal);[32][33] 48% (INS)[34]3:145–60 minutes12–24 hours
14-Cinnamoyloxycodeinone17777 μg
Etonitazepyne180-19055-60 μg
Protonitazepyne180-19055-60 μg
Remifentanil100–20050–100 μg0.05 (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
Protonitazene20050 μg
Ocfentanil125–25040–80 μg
Ro4-1539240–48020-40 μg
Isotonitazene50020 μg
Sufentanil500–1,00010–20 μg4.4
BDPC504~20 μg
C-8813591
4-Phenylfentanyl800
Etonitazene1000-15006,6-10 μg
3-Methylfentanyl1000-1500
N-Desetylisotonitazene1000-20005-10 μg
Etorphine1,000-3,0003.3–10 μg
Ohmefentanyl6300
Acetorphine87001.33 μg
Dihydroetorphine[37]1,000–12,0000.83–10 μg (20–40 μg SL)
Carfentanil[38]10,0001.0 μg7.7
2-Fluorohmefentanil18,000
4-Carboethoxyohmefentanil30,000
Ohmecarfentanil(30,000)
R-30490(10,000–100,000)−
Lofentanil(10,000–100,000)+
14-Methoxymetopon (intraspinally)[39](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.



You should note that this is combined data from different methods of measuring potency on different animals, especially for the most potent ones. So carefully translate this data for the human potency.
For example, Ohmefentanyl potency here is listed as 6300, but it has 8 isomers, one of it - (3R,4S,βS) is considerably stronger than others, or around 6300 stronger than morphine for mouses, BUT for monkeys it is EXTREMELY potent, up to 50.000 times or even more compared to morphine (it was very hard to measure precisely), so more likely it will be similar case for humans. This makes it one of the most potent compounds EVER, not only as pain killers, but also as plain killers, pushing such classical warfare nerve agents as VX out of the game.
Another case is comparison of carfentanil and lofentanil (carfentanil with 3-Methyl group on piperidine ring), later is listed here as 10k-100k potency, but in animal studies is about twice less potent than carfentanil, the opposite case is for humans - it is more potent, and many times more toxic, because it lasts up to 3 days.
There are already compounds with potency rate up to million times compared to morphine (not only by instraspinally route) and likely later appear even more ones, as a result of success in AI prediction of protein folding and binding, but I don't want to list it here, as working with such materials is disaster.
Those who continue the war with amateur and clandestine chemistry should clearly understand that with their actions they only push people to work with more and more potent substances, because year by year it become harder and harder to order chemicals in necessary quantities.
 

HerrHaber

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I hope anyone who shouldn't see this can't read! Or has blurred vision due to obvious reasons (such as myosis).
 

Sassypants

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I dont see most benzimidazole opioids, synthetic opioids, New Psychoactive Substances (NPS)
Some common nitazenes include:
  • isotonitazene
  • metonitazene
  • etonitazene
  • protonitazene.
 

FENTAMAS

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@Sassypants , look more closely, all 4 are in the table, and even some more from the benzimidazole family.

Nevertheless, according to a rough estimate, now there are listed no more than 5% from all powerful opioids.
 

HerrHaber

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metonitazene is there right after fentanyl, the rest are also there and I urge @FENTAMAS not to reveal more than he did, since opiate fans + knowledge of chemistry have been previously proven to be resulting in disastrous MPTP induced tremors like PD.
 

middlemaneu

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it's funny how the terror campaign in USA caused so much fear even in Opioid users about the insanity of the potency of some compounds and believing in such analgesic potency comparison.

First of all Car-F in Humans is nowhere near 10'000x but, really at best best efforts, 1750x. Additional conditions and how it acts drop the potency even more. Of course it's still a hella strong opioid and indeed few ug would kill a non-tolerant person, still people with tolerance with fent or zenes can enjoy Car-F by dosing properly and enjoying one of the most euphoric fentalogues. Only better one I can think about is its cousin, R30490.

But there is plenty of other ones with lower potencies (now that SR-17018 allows an incredibly fast tolerance reduction and quit Zenes/fenta in less than 3 weeks), the myth "always stronger pls" in the RC scene should end.
Acetyl-F (15x), Furanyl-F (25x) and Iso-Butyr-F (20-25x) are some examples of fantastic analogues. Such a shame nobody is manufacturing them anymore.

Even for the Oxycodone users it would be plenty of alternatives of < 10x potency, with full legal status and extremely euphoric. Shame that Dextromoramide analogue experiment failed, this remains the most euphoric opioid of all times for the league 1-10x.

Screw Zenes, not a single one gave me a decet pleasure even closer to the worst fentalogues I tried. It's like pretending 4-MMC analogues got any close to the 4-MMC magic.

But,

for a better future :) and pls don't start synthesizing ETORPHINE analogues, because I doubt we will go any higher after this point xD
 
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