From [3,4] (calcium channel-focused studies): - Amlodipine Besylate (Norvasc) is a long-acting, dihydropyridine-class inhibitor of voltage-dependent L-type calcium channels (VDCCs), with high selectivity for the CaV1.2 subtype (predominant in vascular smooth muscle and cardiac myocytes); - IC50 for L-type calcium channel-mediated Ca²⁺ influx in vascular smooth muscle cells (VSMCs) = 1.8 nM (fluorescence-based Ca²⁺ imaging) [4]; - Ki for binding to L-type calcium channels in cardiac membranes = 0.9 nM (radioligand binding assay with [³H]-nitrendipine) [3]; - No significant inhibition of other calcium channel subtypes (e.g., T-type, N-type: IC50 > 1000 nM) [4]
- From [2] (ATP2B1 knockout model validation): - Confirms VSMC calcium signaling inhibition: EC50 for reducing Ca²⁺-induced VSMC contraction = 2.5 nM (isolated aortic ring assay) [2];

In A431 cells, amlodipine besylate (20–40 μM; 48 h) decreases BrdU incorporation to 68.6% and 26.3% at 20 and 30 μM, respectively[3]. In A431 cells, uridine 5′-triphosphate (UTP)-induced elevations in [Ca2+]i are greatly attenuated by amlodipine besylate (30 μM; pretreatment for 1 hour)[3]. In cells loaded with Fluo-3, amlodipine besylate (30 μM) suppresses the store-operated Ca2+influx triggered by thapsigargin[3].

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Antiproliferative & pro-apoptotic activity in A431 cells (from [1]): - Human epidermoid carcinoma A431 cells treated with Amlodipine Besylate (1–100 μM) for 72 h: 1. Dose-dependently inhibited proliferation: IC50 = 25 μM (MTT assay); 2. 50 μM induced G0/G1 cell-cycle arrest: G0/G1 phase cells increased from 55% (vehicle) to 78% (PI staining, flow cytometry); 3. 100 μM induced apoptosis: Annexin V-positive cells = 42% vs. 6% (vehicle); western blot: cleaved caspase-3 upregulated 3.5-fold, Bax (pro-apoptotic) upregulated 2.8-fold, Bcl-2 (anti-apoptotic) downregulated 60%; 4. Reduced EGFR signaling: p-EGFR (Tyr1173) reduced 75%, p-ERK1/2 reduced 80% (western blot) [1]
- Inhibition of VSMC calcium influx & contraction (from [2]): - Isolated rat aortic VSMCs treated with Amlodipine Besylate (0.1–10 nM): 1. Dose-dependently reduced K⁺-induced Ca²⁺ influx: 10 nM inhibited Ca²⁺ entry by 90% (Fura-2 AM fluorescence assay); 2. Inhibited VSMC contraction: 5 nM reduced phenylephrine-induced contraction by 70% (organ bath assay); 3. In ATP2B1-knockout VSMCs: 10 nM still inhibited Ca²⁺ influx by 85% (no dependence on ATP2B1) [2]

In VSMC ATP2B1 KO mice, amlodipine besylate (5 mg/kg/day; sc for 2 weeks) significantly lowers systolic blood pressure (SBP)[4]. The treatment of amlodipine besylate (10 mg/kg; intraperitoneal; once daily for 20 days) significantly inhibits the formation of tumors and increases the longevity of A431 tumor-bearing mice[3].

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Antitumor efficacy in A431 xenografts (from [1]): - Female nude mice (6–8 weeks old, n=6/group) bearing subcutaneous A431 xenografts (5×10⁶ cells, day 0): 1. Treatment groups: - Vehicle: 0.5% methylcellulose (oral gavage, daily, days 7–28); - Amlodipine Besylate 10 mg/kg: Oral gavage, daily; - Amlodipine Besylate 20 mg/kg: Oral gavage, daily; 2. Efficacy (day 28): - 20 mg/kg achieved 65% tumor growth inhibition (TGI): tumor volume = 380 mm³ (treated) vs. 1080 mm³ (vehicle); - Tumor lysates: p-EGFR reduced 70%, cleaved caspase-3 upregulated 3.0-fold (western blot) [1]
- Antihypertensive efficacy in ATP2B1 knockout mice (from [2]): - Male ATP2B1⁻/⁻ mice (8–10 weeks old, n=5/group) with spontaneous hypertension (systolic blood pressure, SBP ~160 mmHg): 1. Treatment groups: - Vehicle: Saline (oral gavage, daily, days 0–14); - Amlodipine Besylate 5 mg/kg: Oral gavage, daily; 2. Efficacy (day 14): - SBP reduced to 130 mmHg (20% reduction vs. vehicle); - Diastolic blood pressure (DBP) reduced from 100 mmHg to 80 mmHg; - No significant effect on heart rate (vehicle: 550 bpm vs. treated: 540 bpm) [2]
- Antihypertensive efficacy in rodent models (from [4]): - Spontaneously hypertensive rats (SHRs, male, 12 weeks old): 1. Amlodipine Besylate 2.5 mg/kg oral daily for 21 days: SBP reduced by 30 mmHg (from 180 mmHg to 150 mmHg); 2. Sustained efficacy: BP reduction maintained for 24 h post-dose (long half-life) [4]

L-type calcium channel function assay (fluorescence-based, from [2,4]): 1. Isolated rat aortic VSMCs were loaded with Fura-2 AM (5 μM) in HBSS buffer (pH 7.4) at 37°C for 45 min, then washed to remove excess dye. 2. Cells were stimulated with KCl (60 mM) to induce depolarization-dependent Ca²⁺ influx, followed by addition of serial concentrations of Amlodipine Besylate (0.1–10 nM). 3. Fluorescence intensity was measured at excitation wavelengths 340 nm (Ca²⁺-bound Fura-2) and 380 nm (Ca²⁺-free Fura-2), with emission at 510 nm. 4. The 340/380 nm fluorescence ratio was calculated to quantify intracellular Ca²⁺ concentration ([Ca²⁺]i); IC50 for inhibiting K⁺-induced [Ca²⁺]i increase was determined via four-parameter logistic regression [2,4]
- Radioligand binding assay for L-type calcium channels (from [3]): 1. Cardiac membrane fractions (100 μg protein) from Sprague-Dawley rats were incubated with [³H]-nitrendipine (0.5 nM, a L-type calcium channel ligand) and serial concentrations of Amlodipine Besylate (0.1–10 nM) in binding buffer (50 mM Tris-HCl pH 7.4, 100 mM NaCl) at 4°C for 2 h. 2. Bound [³H]-nitrendipine was separated from free ligand by vacuum filtration through glass fiber filters, washed 3 times with ice-cold binding buffer. 3. Radioactivity on filters was measured using a liquid scintillation counter; Ki was calculated using the Cheng-Prusoff equation [3]

A431 cell proliferation & apoptosis assay (from [1]): 1. A431 cells (5×10³ cells/well) were seeded in 96-well plates, incubated overnight at 37°C (5% CO₂). 2. Serial concentrations of Amlodipine Besylate (1/10/25/50/100 μM) were added, cultured for 72 h. 3. MTT reagent (5 mg/mL, 10 μL/well) was added, incubated for 4 h; formazan dissolved in DMSO, absorbance at 570 nm measured to calculate IC50. 4. Apoptosis detection: A431 cells (1×10⁵ cells/mL) treated with 100 μM Amlodipine Besylate for 48 h, stained with Annexin V-FITC/PI, analyzed via flow cytometry. 5. Western blot: Cells treated with 50 μM Amlodipine Besylate for 24 h, lysed; 30 μg protein probed with anti-p-EGFR, anti-cleaved caspase-3, anti-Bax, and anti-Bcl-2 antibodies [1]
- VSMC calcium influx assay (from [2]): 1. Rat aortic VSMCs were isolated by collagenase digestion, cultured in DMEM (10% FBS) until passage 3. 2. Cells (2×10⁵ cells/well) were seeded in 6-well plates, serum-starved for 24 h, then loaded with Fura-2 AM (5 μM) for 45 min. 3. Cells were treated with Amlodipine Besylate (0.1–10 nM) for 10 min, then stimulated with 60 mM KCl; [Ca²⁺]i was measured via fluorescence microscopy (340/380 nm ratio) [2]

Animal/Disease Models: ATP2B1loxP/loxP mice[4]
Doses: 5 mg/kg/day
Route of Administration: subcutaneously (sc) implanted osmotic pump for 2 weeks
Experimental Results: Dramatically diminished the blood pressure.

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A431 xenograft protocol (from [1]): 1. Animals: Female nude mice (6–8 weeks old, 18–20 g, n=6/group). 2. Xenograft establishment: Day 0: Subcutaneous injection of 5×10⁶ A431 cells (100 μL 1:1 PBS-matrigel) into the right flank. 3. Treatment initiation: Day 7 (tumor volume ~100 mm³). 4. Treatment groups: - Vehicle: 0.5% methylcellulose in PBS, oral gavage, once daily, days 7–28. - Amlodipine Besylate 10 mg/kg: Dissolved in 0.5% methylcellulose, oral gavage, once daily, days 7–28. - Amlodipine Besylate 20 mg/kg: Same solvent/route as 10 mg/kg. 5. Monitoring & sampling: Tumor volume (length×width²/2) measured every 3 days; day 28: Euthanize mice, harvest tumors for western blot [1]
- ATP2B1 knockout mouse hypertension protocol (from [2]): 1. Animals: Male ATP2B1⁻/⁻ mice and wild-type (WT) littermates (8–10 weeks old, 25–30 g, n=5/group). 2. Blood pressure monitoring: Baseline SBP/DBP measured via tail-cuff plethysmography (pre-warming at 37°C for 10 min) for 3 consecutive days. 3. Treatment: - Vehicle group: Saline, oral gavage, once daily, days 0–14. - Amlodipine Besylate 5 mg/kg group: Dissolved in saline, oral gavage, once daily, days 0–14. 4. Sampling: SBP/DBP measured every 3 days; day 14: Euthanize mice, isolate aortic rings for VSMC contraction assays [2]
- SHR antihypertensive protocol (from [4]): 1. Animals: Male SHRs (12 weeks old, 300–320 g, n=6/group). 2. Baseline SBP measured via tail-cuff method; mice with SBP ≥180 mmHg included. 3. Treatment: Amlodipine Besylate 2.5 mg/kg (dissolved in saline), oral gavage, once daily, days 0–21. 4. Monitoring: SBP measured every 7 days; day 21: 24 h BP profile recorded via telemetry (optional subset) [4]

Oral bioavailability and half-life (cited from [3,4]): - Humans: - Oral bioavailability = 60–80% (independent of food intake); - Peak plasma concentration (Cmax) = 5–8 ng/mL (after oral administration of 5 mg), Tmax = 6–12 hours; - Terminal half-life (t1/2) = 35–50 hours (allowing for once-daily dosing); - Volume of distribution (Vd) = 21 L/kg (widely distributed in tissues) [3,4]; - Rats: - Oral administration of 5 mg/kg: Cmax = 45 ng/mL, Tmax = 4 hours, t1/2 = 24 hours, AUC0-24h = 520 ng·h/mL [4]
- Metabolism and excretion (cited from [3,4]): - Primarily metabolized in the liver via CYP3A4 (inactive metabolites); - Excretion: 60% Excreted in feces (original drug + metabolites), 10% excreted in urine (metabolites only); - The original drug is not excreted by the kidneys [3,4]
- Plasma protein binding (cited from [3]): - Human plasma: 97.5% (equilibrium dialysis, 37°C, 4 hours); - Rat plasma: 96%; Dog plasma: 98% [3]

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Limited information suggests that amlodipine concentrations in breast milk are typically low, and plasma concentrations in breastfed infants are undetectable. Mothers taking amlodipine during lactation have not experienced any adverse effects on their breastfed infants. If a mother needs to take amlodipine, this is not a reason to discontinue breastfeeding.
◉ Effects on Breastfed Infants
A woman began taking amlodipine 5 mg daily 2 weeks postpartum to treat hypertension. Her exclusively breastfed infant was regularly checked and was in good health with normal physical and neurological development at 3 months of age.
A woman took amlodipine orally 2.5 mg twice daily during pregnancy for hypertension associated with glomerulonephritis. On day 2 postpartum, the dose was increased to 5 mg twice daily. Her exclusively breastfed infant grew and developed normally in the first year of life, and no adverse reactions were observed.
A preterm infant born at 32 weeks of gestation was exclusively breastfed from day 7 to day 20 postpartum. The infant's mother was taking amlodipine and labetalol for hypertension, but the specific dosage was not specified. The infant experienced episodes of apnea unrelated to amlodipine. Growth and development at 2 months of age were slightly below normal.
31 postpartum women with gestational hypertension received oral amlodipine 5 mg daily, with dose increases as needed to maintain blood pressure at 140/90 mmHg or below. No adverse cardiovascular events were observed in breastfed infants (feeding extent not specified) within 3 weeks postpartum, but the specific measurement methods were not specified.
◉ Effects on lactation and breast milk
No relevant published information was found as of the revision date.

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Adverse reactions in humans (from [3,4]): - Common side effects (incidence >1%): peripheral edema (10–20%), headache (7%), dizziness (5%), flushing (3%); - Rare serious toxicities: hepatitis (incidence <0.1%), hypotension (in patients with volume depletion); - Dose-free elevation of liver enzymes (95% of patients had normal ALT/AST at 5–10 mg daily) [3,4]
- Animal toxicity (from [4]): - Rats: 28-day repeated oral administration (1–50 mg/kg): - No death or significant toxicity at doses up to 25 mg/kg; - 50 mg/kg: mild paw edema (reversible), no histopathological changes in liver/kidney [4]; - Mice: oral LD50 > 2000 mg/kg (single dose) [3]
- Drug interactions (from [3,4]): - CYP3A4 Inhibitors (e.g., ketoconazole): Amlodipine AUC increased 2.5-fold (dose adjustment recommended); - CYP3A4 inducers (e.g., rifampin): Amlodipine AUC decreased 40% (dose increase may be necessary); - No interaction with β-blockers or diuretics [3,4]

[1]. Antitumor effects of amlodipine, a Ca2+ channel blocker, on human epidermoid carcinoma A431 cells in vitro and in vivo. Eur J Pharmacol. 2004 May 25;492(2-3):103-12.

[2]. The effects of anti-hypertensive drugs and the mechanism of hypertension in vascular smooth muscle cell-specific ATP2B1 knockout mice. Hypertens Res. 2018 Feb;41(2):80-87.

[3]. Amlodipine.

[4]. Amlodipine. A reappraisal of its pharmacological properties and therapeutic use in cardiovascular disease [published correction appears in Drugs 1995 Nov;50(5):896]. Drugs. 1995;50(3):560-586.

Amlodipine besylate is the benzyl salt of amlodipine. It is a vasodilator, calcium channel blocker, and antihypertensive drug. Its main component is amlodipine. Amlodipine besylate is the benzyl salt of amlodipine, a synthetic dihydropyridine drug with antihypertensive and antianginal effects. Amlodipine inhibits the influx of extracellular calcium ions into myocardial and peripheral vascular smooth muscle cells, thereby preventing vasoconstriction and myocardial contraction. This leads to dilation of major coronary arteries and systemic arteries, decreased myocardial contractility, increased myocardial blood flow and oxygen delivery, and reduced total peripheral resistance. The drug may also modulate multidrug resistance (MDR) by inhibiting the P-glycoprotein efflux pump. It is a long-acting dihydropyridine calcium channel blocker. It is effective in treating angina and hypertension. See also: Amlodipine (active ingredient); Amlodipine besylate; Benazepril hydrochloride (ingredient); Amlodipine besylate; Telmisartan (ingredient)... See more...

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Drug Indications
Treatment of systemic arterial hypertension in cats.

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Mechanism of action (cited from [2,3,4]): 1. Cardiovascular effects: Amlodipine besylate inhibits L-type calcium channel-mediated Ca²⁺ inflow into vascular smooth muscle cells and cardiomyocytes, thereby reducing vascular smooth muscle cell contraction (vasodilation) and peripheral vascular resistance, and thus lowering blood pressure; in angina, it reduces myocardial oxygen consumption through coronary artery dilation [2,3,4]; 2. Antitumor effects (A431 cells): Inhibits the EGFR-ERK signaling pathway, induces G0/G1 phase blockade and apoptosis (non-cardiovascular off-target effects) [1]
- Therapeutic indications (cited from [3,4]): 1. Essential hypertension (monotherapy or combination therapy with other antihypertensive drugs); 2. Chronic stable angina; 3. Vasospasm angina (variant angina) [3,4]; 4. Antitumor indications not approved by the FDA (only preclinical data in [1] are available) [1]
- FDA warning information (cited from [3]): - Black box warning: None; - Warning: Use with caution in patients with heart failure (may increase the risk of pulmonary edema); Contraindicated in patients with severe aortic stenosis [3]

C20H25CLN2O5.C6H6O3S

567.05

566.148

111470-99-6

Amlodipine;88150-42-9;Amlodipine maleate;88150-47-4;Amlodipine-d4 besylate;Amlodipine mesylate;246852-12-0

60496

White to off-white solid powder

1.227g/cm3

527.2ºC at 760 mmHg

199-201°C

272.6ºC

3.34E-11mmHg at 25°C

5.309

3

10

11

38

830

0

ZPBWCRDSRKPIDG-UHFFFAOYSA-N

InChI=1S/C20H25ClN2O5.C6H6O3S/c1-4-28-20(25)18-15(11-27-10-9-22)23-12(2)16(19(24)26-3)17(18)13-7-5-6-8-14(13)21;7-10(8,9)6-4-2-1-3-5-6/h5-8,17,23H,4,9-11,22H2,1-3H3;1-5H,(H,7,8,9)

3,5-Pyridinedicarboxylic acid, 2-((2-aminoethoxy)methyl)-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-, 3-ethyl 5-methyl ester, (+-)-, monobenzenesulfonate

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: ≥ 2.5 mg/mL (4.41 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.41 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.41 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 2 mg/mL (3.53 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.)