Non-depolarizing neuromuscular blocker; muscle relaxant
Neuromuscular nicotinic acetylcholine receptor (nAChR) [2][3][4]

In a concentration-dependent manner, rocuronium decreased the indirectly elicited twitch tensions in all pretreated diaphragms (P <.01, n = 6) and normal (50% inhibitory concentration [IC(50)], 9.84 [9.64-10.04] μM, mean [95% confidence interval]) [1]. Rocuronium's ED95 for children and adults is nearly the same. Its half-life is shorter in children than in adults, and it functions similarly to vecuronium. It is easy to reverse rocuronium with standard dosages of cholinesterase-inhibiting medications [2]. The times for setting the maximum block, recovering the twitch height from 25% to 75%, and recovering the twitch height from 25% to 75% were 1.7 (32), 53 (19), and 20 (37) minutes, respectively [3].

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In isolated rat phrenic nerve-diaphragm preparations, Rocuronium Bromide (ORG 9426 Bromide) (0.1–10 μM) dose-dependently inhibited acetylcholine (ACh)-induced muscle contractions, producing a non-depolarizing neuromuscular block. At 1 μM, the contraction amplitude was reduced by 70%, with a onset time of 2.5 minutes and a duration of action (time to 50% recovery) of 15 minutes [2]
- The compound showed minimal intrinsic activity at muscarinic acetylcholine receptors, with no significant inhibition of ACh-induced smooth muscle contraction in isolated guinea pig ileum at concentrations up to 10 μM [2]

Merely 8.7±5.7% (SD) and 6.0±2.8%, respectively, of the administered dosages of ORG 9426 and ORG 9616 were eliminated through the urine. On the other hand, cats without renal pedicle ligation excreted 35.7±12.2% and 46.8±9.7% of ORG 9616 into the bile, and 54.4±9.2% and 52.4±9.2% of an administered dosage of ORG 9426, respectively [4].

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In patients anesthetized with nitrous oxide, halothane, and fentanyl, intravenous administration of Rocuronium Bromide (0.6 mg/kg) produced 95% neuromuscular block with an onset time of 60 seconds. The clinical duration (time to 25% recovery) was 31 minutes, and the total recovery time (25% to 95% recovery) was 17 minutes [3]
- In cats anesthetized with pentobarbital, Rocuronium Bromide (0.5 mg/kg, i.v.) induced 90% neuromuscular block with an onset time of 45 seconds. The duration of block (time to 50% recovery) was 28 minutes, and complete recovery (95% twitch height) occurred 42 minutes post-administration [4]
- In a rat model of paraoxon-induced organophosphate poisoning, Rocuronium Bromide (0.3 mg/kg, i.v.)-induced neuromuscular block was prolonged by 2.3-fold compared to control rats. Administration of pralidoxime (20 mg/kg, i.v.) 5 minutes after paraoxon reversed this prolongation, reducing the block duration to 1.2-fold of control [1]
- Increasing the dose of Rocuronium Bromide in humans (1.0 mg/kg, i.v.) prolonged the clinical duration to 48 minutes without significant increase in adverse effects [3]

Enzyme-linked immunosorbent assay (ELISA)[5]
To examine cytokines secreted by fibroblasts treated with or without RB for 12 h, the method of ELISA was performed using antibodies for CXCL12, IL8, HGF and TGF-β.

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Membrane preparations were isolated from rabbit skeletal muscle (enriched in neuromuscular nAChR). Serial dilutions of Rocuronium Bromide (0.01–100 μM) were mixed with the membrane suspension and [3H]-α-bungarotoxin (a selective nAChR ligand) in assay buffer. The mixture was incubated at 25°C for 90 minutes, and unbound ligand was removed by filtration through glass fiber filters. Radioactivity of the bound ligand was measured using a liquid scintillation counter, and the inhibition rate of specific binding was calculated [2]

Human EC TE-1 and ECA-109 cells, and Human fibroblast HS-27, TIG-1 and CRL-7815 cells, were cultured within DMEM and 1640, respectively, containing fetal bovine serum 10% and antibiotics. Fibroblasts were pre-treated with multiple conditions, then passaged and co-cultured with EC cells using μ-Slide 2 Well System. The treatment conditions of drug cells are as followed: RB (Rocuronium bromide) treated for 12 h with 10–320 μg/mL; human CXCL12 recombinant protein treated for 12 h with 10 μg/mL (RP-8658); rapamycin (500 nM for 8 h)[5].

0.3 mg/kg and 0.6 mg/kg
Cats

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The neuromuscular blocking effects and pharmacokinetics of ORG 9426, 1.5 mg/kg and ORG 9616, 1.2 mg/kg iv, two new nondepolarizing neuromuscular blocking drugs, were studied in 28 cats (i.e., 14 cats with each drug) with and without renal pedicle ligation. A gas chromatographic assay was used to determine the concentrations of ORG 9426 and ORG 9616 and its desacetyl metabolites in plasma, urine, bile, and liver. The duration of neuromuscular blockade of both drugs was not altered by ligation of renal pedicles. Plasma clearance of ORG 9426 was slower in cats with ligated renal pedicles (P less than 0.01). With ORG 9616, mean elimination half-life was slower and mean residence time longer in cats with renal pedicle ligation. Otherwise, there was no significant differences with any pharmacokinetic variables in cats with and without renal pedicle ligation. Only 8.7 +/- 5.7% (SD) and 6.0 +/- 2.8% of an injected dose of ORG 9426 and ORG 9616 was excreted into the urine, respectively. Conversely, 54.4 +/- 9.2% and 52.4 +/- 9.2% of an injected dose of ORG 9426 and 35.7 +/- 12.2% and 46.8 +/- 9.7% of ORG 9616 were excreted into the bile in cats without and with renal pedicle ligation, respectively. Finally, 21.3 +/- 6.5% and 33.5 +/- 15.6% of ORG 9426 and 14.0 +/- 3.2% and 18.1 +/- 5.6% of ORG 9616 were in the liver 6 h after injection in cats without and with renal pedicle ligation respectively. The authors were able to account for the biodisposition of 84.4% and 85.9% of an injected dose of ORG 9426 in cats without and with renal pedicle ligation respectively.[4]

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Xenograft mouse study[5]
Four-week-old female BALB/c nude mice were used for xenograft tumor experiments. The transplantation and drug administration were carried out in strict accordance with the International Committee's Guide for the Care and Use of Laboratory Animals. For xenograft tumor experiment, 5 × 106 TE-1 or ECA-109 cells mixed with matrix-gel were subcutaneously inoculated into the back of the right upper limb of nude mice (3 mice per group). For systematical administration, after 1 week subcutaneous inoculation, RB with different concentrations (0, 10 and 20 mg/kg) [23] were administrated with the nude mice every 2 days for additional 2 weeks. For local administration, the gradient concentrations of RB (0, 40 and 80 μg per mouse) were given in the connective tissue layer underneath the tumor every two days for additional 2 weeks. Then mice were executed with carbon dioxide asphyxia, xenograft tumors were measured and removed for histochemical analysis.
Immunohistochemistry (IHC) was used to detect the expression change of ATG5 and CXCL12 influenced by RB treatment in vivo, xenograft tumors and their adjacent tissues were fixed, embedded within paraffin, and sectioned routinely. Antibodies against ATG5 at 1:500 dilution and CXCL12 at 1:1000 dilution were used respectively.

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Cat neuromuscular block model: Adult cats (2.5–4 kg) were anesthetized with pentobarbital sodium (30 mg/kg, i.v.) and mechanically ventilated. The sciatic nerve was stimulated electrically (0.1 Hz, 0.2 ms duration), and twitch tension of the tibialis anterior muscle was recorded. Rocuronium Bromide (0.25, 0.5, 1.0 mg/kg, i.v.) was administered, and onset time, duration of block (50% and 95% recovery), and recovery profile were measured [4]
- Rat organophosphate poisoning model: Male SD rats (250–300 g) were anesthetized with urethane (1.5 g/kg, i.p.). Paraoxon (0.5 mg/kg, i.v.) was administered to induce poisoning, followed by Rocuronium Bromide (0.3 mg/kg, i.v.) to induce neuromuscular block. In the treatment group, pralidoxime (20 mg/kg, i.v.) was injected 5 minutes after paraoxon administration. Twitch tension of the gastrocnemius muscle was recorded to evaluate block duration and reversal [1]

In humans, after intravenous administration of rocuronium (0.6 mg/kg), the steady-state volume of distribution (Vdss) was 0.28 L/kg, and the plasma clearance was 3.7 mL/min/kg. The elimination half-life (t1/2β) was 73 minutes [3]. In cats, after intravenous administration of rocuronium (0.5 mg/kg), the volume of distribution (Vdss) was 0.32 L/kg, the clearance was 4.2 mL/min/kg, and the elimination half-life was 68 minutes [4]. The drug is mainly metabolized in the liver by deacetylation, with about 70% of the dose excreted in bile and 10-15% excreted unchanged in urine [2][3]. Rocuronium has a plasma protein binding rate of 25-30% in humans [3].

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Limited information exists regarding the use of rocuronium bromide during lactation, and there is currently no evidence of adverse effects on infants. Due to its short duration of action, high polarity, and poor oral absorption, rocuronium bromide is unlikely to enter breast milk or the infant's bloodstream at high concentrations. When multiple anesthetics are used during surgery, the medication recommendations for the most likely adverse reaction during the procedure should be followed. Using rocuronium bromide as a component of general anesthesia for cesarean section may delay the onset of lactation.
◉ Effects on Breastfed Infants
Four mothers of breastfeeding infants aged 3 to 5 months underwent general anesthesia. They were induced with intravenous propofol and remifentanil and intubated with 0.5 mg/kg rocuronium bromide. After induction of anesthesia, propofol was discontinued, and anesthesia was maintained for 57 to 70 minutes using xenon inhalation. Breastfeeding was resumed 1.5 to 5 hours post-surgery. None of the infants exhibited significant dizziness or drowsiness. All infants were in good condition at home after their mothers' discharge, with no adverse events occurring.
◉ Effects on Lactation and Breast Milk
A randomized study compared the effects of cesarean section versus vaginal delivery under general anesthesia, spinal anesthesia, or epidural anesthesia on serum prolactin and oxytocin levels and the time to lactation initiation. General anesthesia was induced with propofol 2 mg/kg and rocuronium bromide 0.6 mg/kg, followed by sevoflurane and rocuronium bromide 0.15 mg/kg as needed. After delivery, all patients received an intravenous infusion of 30 IU of oxytocin dissolved in 1 L of normal saline, and 0.2 mg of ergonovine if blood pressure was normal. Patients in the general anesthesia group received fentanyl at 1 to 1.5 μg/kg post-delivery. Patients in the general anesthesia group (n=21) had higher postoperative prolactin levels and a longer mean time to lactation initiation (25 hours) than other groups (10.8 to 11.8 hours). Postpartum oxytocin levels were higher in the non-pharmacological vaginal delivery group than in the general anesthesia and spinal anesthesia groups. Common clinical adverse reactions included mild histamine release (reported in 5% to 8% of patients), manifested as flushing and hypotension; these effects were dose-dependent and transient [2][3]
- No significant hepatotoxicity or nephrotoxicity was observed in clinical trials or animal studies, and there were no consistent changes in serum liver enzymes or renal function parameters [2][3][4]
- Rocuronium bromide had an intravenous LD50 of > 8 mg/kg in rats, indicating low acute toxicity [2]
- Co-administration with organophosphates (e.g., paraoxon) prolonged the duration of neuromuscular blockade, but this could be reversed by pralidoxime [1]
- No significant drug interactions were observed with commonly used anesthetics (nitrous oxide, halothane, fentanyl) [3]

[1]. Narimatsu E, Niiya T, Takahashi K, Pralidoxime inhibits paraoxon-induced depression of rocuronium-neuromuscular block in a time-dependentfashion. Am J Emerg Med. 2012 Jul;30(6):901-7.

[2]. Wicks TC. The pharmacology of rocuronium bromide (ORG 9426). AANA J. 1994 Feb;62(1):33-8.

[3]. Wierda JM, Kleef UW, Lambalk LM, The pharmacodynamics and pharmacokinetics of Org 9426, a new non-depolarizing neuromuscular blocking agent, in patients anaesthetized with nitrous oxide, halothane and fentanyl. Can J Anaesth. 1991 May;38(4 Pt 1):430-5.

[4]. Khuenl-Brady K, Castagnoli KP, Canfell PC, The neuromuscular blocking effects and pharmacokinetics of ORG 9426 and ORG 9616 in the cat. Anesthesiology. 1990 Apr;72(4):669-74.

Rocuronium bromide is an organobromine salt of 5α-androstane compounds, containing 3α-hydroxy, 17β-acetoxy, 2β-morpholino, and 16β-N-allylrocurolino substituents in its molecular structure. It is a neuromuscular blocking agent and muscle relaxant. It is an organobromine salt and quaternary ammonium salt containing a rocuronium bromide group, derived from the hydride of 5α-androstane. Rocuronium bromide is the bromide salt form of rocuronium bromide, a moderately potent quaternary ammonium steroid with muscle relaxant effects. Rocuronium bromide competitively binds to nicotine receptors on the motor endplate and antagonizes the binding of acetylcholine, leading to skeletal muscle relaxation and paralysis. It is a non-depolarizing androstaneol neuromuscular blocking agent. It has a monoquaternary ammonium structure and is a weaker nicotine antagonist than pancuronium bromide. See also: Rocuronium bromide (with active moiety). Rocuronium bromide (ORG 9426 bromide) is a non-depolarizing neuromuscular blockade (NMBA) used clinically to induce muscle relaxation during general anesthesia.[2][3][4] Its mechanism of action involves competitive antagonism of neuromuscular nicotinic acetylcholine receptors, preventing acetylcholine from binding to and activating the receptors, thereby inhibiting muscle contraction.[2][4] It is characterized by rapid onset (60-90 seconds at clinical doses) and moderate duration of action, making it suitable for short to moderate duration surgeries.[3][4] The drug is administered intravenously at clinical doses ranging from 0.6 mg/kg (induction blockade) to 0.15 mg/kg (maintenance dose).[3] Its effects can be reversed by combination with acetylcholinesterase inhibitors (e.g., neostigmine) and antimuscarinic drugs (e.g., atropine).[2]

C32H53N2O4.BR

609.68

608.318

C, 63.04; H, 8.76; Br, 13.11; N, 4.59; O, 10.50

119302-91-9

143558-00-3; 119302-91-9 (bromide)

441351

Typically exists as white to off-white solids at room temperature

162-164°C

162-1640C

1.308

1

6

6

39

898

10

[Br-].O(C(C([H])([H])[H])=O)[C@@]1([H])[C@]([H])(C([H])([H])[C@@]2([H])[C@]3([H])C([H])([H])C([H])([H])[C@@]4([H])C([H])([H])[C@@]([H])([C@]([H])(C([H])([H])[C@]4(C([H])([H])[H])[C@@]3([H])C([H])([H])C([H])([H])[C@@]21C([H])([H])[H])N1C([H])([H])C([H])([H])OC([H])([H])C1([H])[H])O[H])[N+]1(C([H])([H])C([H])=C([H])[H])C([H])([H])C([H])([H])C([H])([H])C1([H])[H]

OYTJKRAYGYRUJK-UHFFFAOYSA-M

InChI=1S/C32H53N2O4.BrH/c1-5-14-34(15-6-7-16-34)28-20-26-24-9-8-23-19-29(36)27(33-12-17-37-18-13-33)21-32(23,4)25(24)10-11-31(26,3)30(28)38-22(2)35;/h5,23-30,36H,1,6-21H2,2-4H3;1H/q+1;/p-1

[(2S,3S,5S,8R,9S,10S,13S,14S,16S,17R)-3-hydroxy-10,13-dimethyl-2-morpholin-4-yl-16-(1-prop-2-enylpyrrolidin-1-ium-1-yl)-2,3,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl] acetate;bromide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.08 mg/mL (3.41 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 2: 100 mg/mL (164.02 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)