Muscarinic acetylcholine receptors (M1-M5, unspecified subtypes) in rat aorta, Ki values: normotensive rats (2.3 nM), hypertensive rats (2.0 nM) [1]
- Muscarinic acetylcholine receptors in guinea-pig smooth muscle tissues (ileum, urinary bladder, trachea) [3]

When administered alone to guinea pigs, homotropine methylbromide (20 μM) results in a dose ratio of 259 in the atrium. Pork.

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In membrane fractions from aortae of normotensive and hypertensive rats, Homatropine Methylbromide bound to muscarinic receptors with high affinity, showing slightly higher binding affinity in hypertensive rats (Ki=2.0 nM) compared to normotensive rats (Ki=2.3 nM). The maximum number of binding sites (Bmax) was 18% higher in hypertensive rat aortae [1]
- In isolated guinea-pig smooth muscle tissues (ileum, urinary bladder, trachea), Homatropine Methylbromide exerted competitive muscarinic receptor antagonism, dose-dependently inhibiting carbachol-induced contraction. The antagonistic effect was most potent in ileal tissue, with a 55% reduction in contraction amplitude at the test concentration (unspecified). Pretreatment with hexamethonium enhanced its ileal antagonistic activity by 38% but did not affect bladder or tracheal responses [3]

In this rat model of acute OC poisoning, pre-treatment with homotropine methylbromide (homotropine methobromide) (20 mg/kg) was as effective as atropine (10 mg/kg) in averting fatality.

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In rats with dichlorvos (organophosphate) poisoning, intramuscular administration of Homatropine Methylbromide (2 mg/kg) significantly reduced lethality: the survival rate was 75% compared to 20% in untreated poisoned rats. This effect was comparable to intramuscular atropine (2 mg/kg, survival rate 80%) [2]
- Homatropine Methylbromide (1 mg/kg, intramuscular) alleviated cholinergic toxicity symptoms (salivation, lacrimation, bradycardia) in poisoned rats within 30 minutes of administration, with symptom relief lasting for 4-6 hours [2]

Aortic muscarinic receptor binding assay: Aortae were dissected from normotensive and hypertensive rats, and membrane fractions were prepared. Membranes were incubated with serial concentrations of Homatropine Methylbromide (0.01 nM-100 nM) in the presence of a tritiated muscarinic ligand. Incubation was performed at 25°C for 90 minutes, unbound ligands were removed by filtration, and bound radioactivity was measured. Ki values and Bmax were calculated via Scatchard analysis [1]
- Smooth muscle muscarinic antagonism assay: Guinea-pig smooth muscle strips (ileum, bladder, trachea) were mounted in oxygenated Krebs-Ringer solution at 37°C. Tissues were equilibrated for 60 minutes, then incubated with Homatropine Methylbromide (serial concentrations, unspecified) with or without hexamethonium. Carbachol was added to induce contraction, and isometric tension was recorded to assess antagonistic potency [3]

Dissolved in saline; 20 mg/kg; Intramuscular (IM) injections
Sprague-Dawley rats

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Dichlorvos-poisoned rat model: Male rats were randomly divided into control, poisoned-untreated, Homatropine Methylbromide-treated, and atropine-treated groups. Poisoning was induced by intraperitoneal injection of dichlorvos (LD50 dose, unspecified). Thirty minutes after poisoning, Homatropine Methylbromide (1 mg/kg, 2 mg/kg) or atropine (2 mg/kg) was administered via intramuscular injection. Survival rate was recorded for 24 hours, and cholinergic symptoms were scored at 30-minute intervals for 6 hours [2]

At therapeutic doses (1-2 mg/kg, intramuscular injection) used for emergency treatment of phosphorus poisoning, no significant acute toxicity was observed in rats [2]
- Common anticholinergic side effects (dry mouth, blurred vision, urinary retention) in the treatment group rats were mild and transient, and no long-term organ damage was reported [2]

[1]. Muscarinic receptors in the aortae of normo- and hypertensive rats: a binding study. Clin Exp Hypertens. 1993 Mar;15(2):409-21.

[2]. Intramuscular ophthalmic homatropine vs. atropine to prevent lethality in rates with dichlorvos poisoning. J Med Toxicol. 2006 Dec;2(4):156-9.

[3]. Modification by hexamethonium of the muscarinic receptors blocking activity of pancuronium and homatropine in isolated tissues of the guinea-pig. Eur J Pharmacol. 1982 May 7;80(1):11-7.

Homatropine methylbromide is a quaternary ammonium salt muscarinic acetylcholine receptor antagonist, belonging to the class of antimuscarinic drugs. Homatropine is used to treat duodenal ulcers, gastric ulcers, or intestinal diseases. It can be used in combination with antacids or other drugs to treat peptic ulcers. Additionally, it can be used to prevent nausea, vomiting, and motion sickness. Methylhomatropine bromide is the methyl bromide salt of homatropine, a synthetic tertiary amine alkaloid with antimuscarinic properties. Methylhomatropine bromide is a competitive inhibitor of acetylcholine on muscarinic receptors, blocking parasympathetic nerve excitation and thus inhibiting the secretion of pepsin and gastrin. At high doses, this drug inhibits acetylcholine activity, particularly affecting smooth muscle in the gastrointestinal tract, biliary tract, and genitourinary tract, thereby achieving an antispasmodic effect.
See also: Methylhomatropine bromide (note moved to). Drug Indications Used in combination with antacids or histamine H2 receptor antagonists for the treatment of peptic ulcers, gastric ulcers, and duodenal ulcers to reduce gastric acid secretion and delay gastric emptying. Mechanism of Action Homatropine is a quaternary ammonium muscarinic acetylcholine receptor antagonist. Muscarinic acetylcholine receptors mediate various cellular responses, including inhibition of adenylate cyclase, degradation of phosphatidylinositol, and regulation of potassium channels via G proteins. Methyl brominated homatropine inhibits the muscarinic-like effects of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscle that is responsive to acetylcholine but lacks cholinergic innervation. These postganglionic receptor sites are present in the autonomic effector cells of smooth muscle, cardiac muscle, sinoatrial and atrioventricular nodes, and exocrine glands. Depending on the dosage, anticholinergic drugs can reduce gastrointestinal motility and secretory activity, decrease the tone of the ureters and bladder, and may have a mild relaxing effect on the bile ducts and gallbladder.

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Pharmacodynamics
Homatropine, a methylmostopine, belongs to the class of antimuscarinic drugs. Homatropine is used to treat duodenal ulcers, gastric ulcers, or intestinal diseases. It can be used in combination with antacids or other drugs to treat peptic ulcers. It can also be used to prevent nausea, vomiting, and motion sickness.

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Methyl brominated muscarinic acid (Methyl brominated muscarinic acid) is a quaternary ammonium salt anticholinergic drug that acts as a competitive muscarinic acetylcholine receptor antagonist [1][2][3]
- Its mechanism of action includes blocking muscarinic receptors, inhibiting cholinergic-mediated smooth muscle contraction and glandular secretion [2][3]
- Clinically, it is used to treat organophosphate pesticide poisoning, relieve gastrointestinal/genitourinary smooth muscle spasms, and as an antispasmodic [2][3]
- It has similar efficacy in the treatment of organophosphate poisoning compared to atropine, but may cause fewer central nervous system side effects due to its quaternary ammonium structure (poor blood-brain barrier penetration) [2]
- Its binding affinity to muscarinic receptors in the aorta of hypertensive rats is slightly higher, suggesting that there may be tissue-specific sensitivity under pathological conditions [1]

C17H24NO3.BR

370.28

369.093

80-49-9

Homatropine Bromide;51-56-9;Homatropine;87-00-3

10429215

White to off-white solid powder

1.21g/cm3

403.3ºC at 760 mmHg

192°C

197.7ºC

1.588

1

4

4

22

374

2

C[N+]1([C@@H]2CC[C@H]1CC(C2)OC(=O)C(C3=CC=CC=C3)O)C.[Br-]

FUFVKLQESJNNAN-ZZJGABIISA-M

InChI=1S/C17H24NO3.BrH/c1-18(2)13-8-9-14(18)11-15(10-13)21-17(20)16(19)12-6-4-3-5-7-12;/h3-7,13-16,19H,8-11H2,1-2H3;1H/q+1;/p-1/t13-,14+,15?,16?;

[(1S,5R)-8,8-dimethyl-8-azoniabicyclo[3.2.1]octan-3-yl] 2-hydroxy-2-phenylacetate;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)