hERG potassium channel [1]
- ERK1/2 MAPK [2]
- p38 MAPK [2]

Amiodarone hydrochloride inhibits the inward IhERG tail with an IC50 of 117.8 nM in 94 mM high-K+ external solution ([K+]e) [1]. Amiodarone hydrochloride (1 μM) blocks inwardIhERG by 68.8±6.1%, and concentration response data gave IC50 with h values of 765.5±287.8 nM and 0.9±0.4 for T623A hERG [1]. Amiodarone (1 μM) blocks inward IhERG with IC50 and h values of 979.2±84.3 nM and 1.1±0.1 for S624A hERG [1]. Amiodarone (1-6 μg/mL) promotes cell proliferation in human embryonic lung fibroblasts (HELFs), while PD98059 or SB203580 decreases this action [2]. Amiodarone (1-6 μg/mL) does not induce apoptosis in HELFs cells. Amiodarone hydrochloride (greater than 15 μg/mL) causes apoptosis [2]. Amiodarone hydrochloride (1, 3 and 6 μg/mL; 24 hours) stimulates α-SMA and vimentin mRNA and protein expression associated by an increase in ERK1/2 and p38 MAPK phosphorylation [2].

---

In HEK293 cells and Xenopus oocytes expressing hERG potassium channels, Amiodarone HCl (NSC 85442) (1-50 μM) blocked hERG-mediated potassium currents in a concentration-dependent manner. It preferentially bound to the open/inactivated states of the channel, prolonging the inactivation recovery time and reducing tail current amplitude by 62% at 20 μM. Mutagenesis studies identified key amino acid residues (Y652, F656) in the hERG pore domain involved in drug binding[1]
- In human skin fibroblasts and cardiac fibroblasts, Amiodarone HCl (NSC 85442) (1-10 μM) induced cell proliferation in a concentration-dependent manner, with a 58% increase in cell viability at 5 μM. It promoted myofibroblast differentiation by upregulating α-smooth muscle actin (α-SMA) and collagen type I expression (mRNA and protein levels). The effect was mediated by phosphorylation of ERK1/2 (by 70% at 5 μM) and p38 MAPK (by 65% at 5 μM), as confirmed by specific MAPK inhibitors[2]
- In primary mouse ventricular myocytes, Amiodarone HCl (NSC 85442) (5-25 μM) remodeled the expression of ion channel transcripts in a time- and concentration-dependent manner. At 15 μM (48 hours), it downregulated Scn5a (Nav1.5) mRNA by 45%, Kcnh2 (hERG) mRNA by 38%, and upregulated Kcnq1 (IKs) mRNA by 52% and Cacna1c (Cav1.2) mRNA by 40%[3]

Animal models of pulmonary fibrosis can be created with the use of amiodarone hydrochloride in animal modeling. Chronic administration of 90 and 180 mg/kg/day of amiodarone hydrochloride causes a dose-dependent modification of ion channel expression, which is correlated with the drug's effects on cardiac electrophysiology [3].

---

In C57BL/6 mice, oral administration of Amiodarone HCl (NSC 85442) (10 mg/kg, once daily for 4 weeks) remodeled the expression of cardiac ion channel transcripts. Cardiac tissue analysis showed downregulation of Scn5a (35%), Kcnh2 (30%), and Kcnj2 (IK1, 28%) mRNA, and upregulation of Kcnq1 (48%), Cacna1c (36%), and Cacna1d (Cav1.3, 32%) mRNA. No significant changes in heart rate or QT interval were observed[3]

hERG channel binding and activity assay: HEK293 cells were transfected with wild-type or mutant hERG plasmids, and Xenopus oocytes were injected with hERG cRNA. After culture, whole-cell patch-clamp recordings were performed to measure hERG tail currents. Amiodarone HCl (NSC 85442) (1-50 μM) was added to the extracellular solution, and voltage protocols (holding potential -80 mV, depolarization to +40 mV for 500 ms, repolarization to -50 mV) were used to assess current inhibition and binding kinetics[1]
- MAPK phosphorylation assay: Fibroblasts were serum-starved and treated with Amiodarone HCl (NSC 85442) (1-10 μM) for 15-60 minutes. Total protein was extracted, and Western blot was performed using phospho-specific antibodies against ERK1/2 and p38 MAPK. Band intensity was quantified to evaluate phosphorylation levels[2]

Cell Proliferation Assay[2]
Cell Types: HELFs
Tested Concentrations: 1, 3 and 6 μg/mL
Incubation Duration: 24 hrs (hours)
Experimental Results: Increased HELFs proliferation compared with the control group.

---

Western Blot Analysis[2]
Cell Types: HELFs
Tested Concentrations: 1, 3 and 6 μg/mL
Incubation Duration: 24 hrs (hours)
Experimental Results: α-SMA and vimentin were increased Dramatically in a dose-dependent manner.

---

RT-PCR[2]
Cell Types: HELFs
Tested Concentrations: 1, 3 and 6 μg/mL
Incubation Duration: 24 hrs (hours)
Experimental Results: Induced an increase of α-SMA and vimentin mRNA expression.

---

hERG channel cell assay: Transfected HEK293 cells or hERG-expressing oocytes were plated on glass coverslips. Amiodarone HCl (NSC 85442) was applied at gradient concentrations, and hERG currents were recorded by patch-clamp. Mutant hERG channels (Y652A, F656A) were used to verify key binding residues[1]
- Fibroblast proliferation and differentiation assay: Fibroblasts were seeded in 96-well plates (proliferation) or 6-well plates (differentiation). Amiodarone HCl (NSC 85442) (1-10 μM) was added, and cells were cultured for 24-72 hours. Cell viability was detected by MTT assay. α-SMA and collagen type I expression was analyzed by Western blot and immunofluorescence staining. MAPK inhibitors were used to confirm signaling pathways[2]
- Ion channel transcript assay: Primary mouse ventricular myocytes were isolated and cultured. Amiodarone HCl (NSC 85442) (5-25 μM) was added, and cells were incubated for 24-72 hours. Total RNA was extracted, and qPCR was performed to measure mRNA levels of Scn5a, Kcnh2, Kcnq1, Cacna1c, and other ion channel genes[3]

Animal/Disease Models: Tenweeks old male C57BL/6 mice[3]
Doses: 30, 90, and 180 mg/kg/day
Route of Administration: Treated po (oral gavage) for 6 weeks
Experimental Results: Mice treated with 90 and 180 mg/kg/day had diminished body and heart weights, although their heart weight-to-body weight ratios were not Dramatically different from sham. 6-week treatment induced a decrease in plasma triiodothyronine and an increase in reverse triiodothyronine. This effect reached significance for the 90 and 180 but not for the 30 mg/kg/day dose groups.

---

Cardiac ion channel transcript remodeling mouse model: Male C57BL/6 mice (8-10 weeks old) were randomly divided into control and treatment groups. Amiodarone HCl (NSC 85442) was suspended in 0.5% carboxymethylcellulose sodium (CMC-Na) and administered orally at 10 mg/kg once daily for 4 weeks. Control mice received equal volume of 0.5% CMC-Na. Mice were euthanized, and hearts were harvested to extract total RNA for qPCR analysis of ion channel transcripts[3]

Absorption, Distribution and Excretion
The peak plasma concentration (Cmax) of amiodarone is typically reached 3 to 7 hours after administration. Following a single intravenous dose of amiodarone, the onset of action is generally 1 to 30 minutes, with therapeutic effects lasting 1 to 3 hours. The steady-state plasma concentration of amiodarone ranges from 0.4 to 11.99 μg/ml; for patients with arrhythmias, it is recommended to maintain a steady-state concentration between 1.0 and 2.5 μg/ml. It is noteworthy that the onset of action of amiodarone may sometimes begin after 2 to 3 days, but typically takes 1 to 3 weeks, even with a high loading dose. The bioavailability of amiodarone varies in clinical studies, averaging between 35% and 65%. Food Effects: In healthy subjects, a single 600 mg dose of amiodarone administered immediately after consuming a high-fat diet resulted in a 2.3-fold increase in AUC and a 3.8-fold increase in Cmax. Food also enhances absorption, reducing Tmax by approximately 37%. Amiodarone is primarily eliminated through hepatic metabolism and bile excretion. Small amounts of desethylamiodarone (DEA) can be detected in urine. In a pharmacokinetic study of 3 healthy individuals and 3 patients with supraventricular tachycardia (SVT), the volume of distribution (VOD) ranged from 9.26 to 17.17 L/kg in healthy volunteers and from 6.88 to 21.05 L/kg in SVT patients. Prescribing information indicates significant individual variability in the VOD of amiodarone, with an average VOD of approximately 60 L/kg. Amiodarone accumulates systemically, particularly in adipose tissue and highly vascularized organs, including the lungs, liver, and spleen. The major metabolite of amiodarone, desethylamiodarone (DEA), is present in higher concentrations in the same tissues as amiodarone. A clinical study showed that the clearance rate of amiodarone after intravenous administration was 220 to 440 ml/hr/kg in patients with ventricular fibrillation and ventricular tachycardia. Another study determined that the systemic clearance of amiodarone after a single intravenous injection ranged from 0.10 to 0.77 L/min. Renal impairment did not appear to affect amiodarone clearance, but hepatic impairment may have reduced it. Patients with cirrhosis showed significantly reduced peak DEA plasma concentrations (Cmax) and mean amiodarone concentrations, but no significant change in amiodarone plasma concentrations. Severe left ventricular dysfunction prolongs the half-life of DEA. Regarding monitoring: There are currently no guidelines for adjusting amiodarone dosage in patients with renal, hepatic, or cardiac abnormalities. Close clinical monitoring is recommended for patients receiving long-term amiodarone treatment, especially elderly patients and those with severe left ventricular dysfunction. Metabolism/Metabolites: This drug is metabolized by CYP3A4 and CYP2C8 enzymes to the major metabolite, desethylamiodarone (DEA). CYP3A4 enzymes are present in the liver and intestine. Hydroxyl metabolites of DEA have been identified in mammals, but their clinical significance remains unclear. Amiodarone's known metabolites include N-deethylamiodarone. Amiodarone is primarily metabolized in the liver via CYP2C8 (less than 1% of the unchanged drug is found in urine) and may affect the metabolism of several other drugs. The major metabolite of amiodarone is deethylamiodarone (DEA), which also has antiarrhythmic effects. Grapefruit juice inhibits amiodarone metabolism, leading to elevated serum amiodarone levels. Elimination pathway: Amiodarone is primarily eliminated via hepatic metabolism and bile excretion; very little amiodarone or DEA is excreted in urine. Half-life: 58 days (range 15-142 days). The terminal half-life of amiodarone varies from patient to patient, but is generally long, ranging from approximately 9-100 days. Half-life data vary depending on the source. According to amiodarone's prescribing information, the mean apparent plasma terminal elimination half-life of amiodarone is 58 days (range 15 to 142 days). The terminal half-life of the active metabolite (DEA) ranges from 14 to 75 days. One study showed that the plasma half-life of amiodarone after a single dose ranged from 3.2 to 79.7 hours.

Toxicity Summary
The antiarrhythmic effect of amiodarone can be attributed to at least two main mechanisms. It prolongs the duration of the cardiomyocyte action potential (phase 3) and the refractory period, and acts as a non-competitive α and β adrenergic inhibitor. Toxicity Data
Intravenous injection, mice: LD50 = 178 mg/kg.

[1]. Yihong Zhang,et al. Interactions between amiodarone and the hERG potassium channel pore determined with mutagenesis and in silico docking. Biochem Pharmacol. 2016 Aug 1;113:24-35.
[2]. Jie Weng, et al. Amiodarone induces cell proliferation and myofibroblast differentiation via ERK1/2 and p38 MAPK signaling in fibroblasts. Biomed Pharmacother. 2019 Jul;115:108889.
[3]. Sabrina Le Bouter, et al. Long-term amiodarone administration remodels expression of ion channel transcripts in the mouse heart. Circulation. 2004 Nov 9;110(19):3028-35.

Pharmacodynamics
Intravenous amiodarone relaxes vascular smooth muscle, reduces peripheral vascular resistance (afterload), and slightly increases cardiac index. This route of administration also reduces cardiac conduction, thereby preventing and treating arrhythmias. However, oral amiodarone does not cause significant changes in left ventricular ejection fraction. Similar to other antiarrhythmic drugs, controlled clinical trials have not demonstrated that oral amiodarone improves survival. Amiodarone prolongs QRS duration and QT interval. Furthermore, it reduces sinoatrial node automaticity and atrioventricular node conduction velocity. The automaticity of ectopic pacemakers is also suppressed. Taking amiodarone with high iodine content may also lead to thyrotoxicosis or hypothyroidism because amiodarone interferes with normal thyroid function.

---

Amiodarone hydrochloride (NSC 85442) is a broad-spectrum class III antiarrhythmic drug with multiple ion channel blocking activities [1][3]
- Its core antiarrhythmic mechanism involves blocking hERG potassium channels, prolonging myocardial repolarization and refractory period [1]
- This drug induces fibroblast proliferation and myofibroblast differentiation through the ERK1/2 and p38 MAPK signaling pathways, and long-term use may be associated with myocardial fibrosis [2]
- Long-term administration can remodel the transcriptional expression of ion channels in mouse hearts, which may contribute to its therapeutic effect and potential arrhythmogenic risk [3]
- Mutagenesis and computer simulation docking studies have confirmed that amiodarone hydrochloride (NSC 85442) binds to the hERG channel pore domain through key amino acid residues (Y652, F656) [1]

C25H29I2NO3.HCL

681.77

681

19774-82-4

Amiodarone-d4 hydrochloride;1216715-80-8;Amiodarone;1951-25-3

2157

White to off-white solid powder

1.58 g/cm3

635.1ºC at 760 mmHg

154-158°C

337.9ºC

7.738

0

4

11

31

547

0

ITPDYQOUSLNIHG-UHFFFAOYSA-N

InChI=1S/C25H29I2NO3.ClH/c1-4-7-11-22-23(18-10-8-9-12-21(18)31-22)24(29)17-15-19(26)25(20(27)16-17)30-14-13-28(5-2)6-3;/h8-10,12,15-16H,4-7,11,13-14H2,1-3H3;1H

2-Butyl-3-benzofuryl 4-(2-(diethylamino)ethoxy)-3,5-diiodophenyl ketone hydrochloride

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 (e.g. under nitrogen), avoid exposure to moisture and light.

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: ≥ 2.5 mg/mL (3.67 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (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 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 2.5 mg/mL (3.67 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (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 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 2.5 mg/mL (3.67 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

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