PDE5 (IC50 = 0.7 nM); PDE6 (IC50 = 11 nM); PDE1 (IC50 = 180 nM); PDE3 (IC50 >1000 nM); PDE4 (IC50 >1000 nM)
Vardenafil HCl targets phosphodiesterase type 5 (PDE5) (IC50 = 0.7 nM for human PDE5A1; Ki = 0.9 nM; competitive inhibition mode against cGMP) [1]
Vardenafil HCl shows selectivity over other PDE subtypes (PDE1: IC50 = 120 nM; PDE2: IC50 > 10,000 nM; PDE3: IC50 > 10,000 nM; PDE4: IC50 = 4,500 nM; PDE6: IC50 = 18 nM; PDE7-11: IC50 > 10,000 nM) [1]

Vardenafil hydrochloride has an IC50 of 0.7 nM, which selectively prevents PDE5 from hydrolyzing cGMP[1]. The body's sinuses enlarge and blood flow is enhanced when vardenafil hydrochloride raises intracellular cGMP levels in the corpus cavernosum tissue of the penis [3].

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- PDE5 inhibitory activity: Vardenafil HCl potently and selectively inhibits recombinant human PDE5A1/A2/A3 isoforms, with IC50 values of 0.7 nM, 1.1 nM, and 0.9 nM respectively. It competitively blocks cGMP hydrolysis, increasing intracellular cGMP levels [1]
- Relaxation of corpus cavernosum smooth muscle: In isolated rabbit corpus cavernosum smooth muscle strips pre-contracted with phenylephrine, Vardenafil HCl (0.1-100 nM) induces concentration-dependent relaxation, with EC50 = 2.3 nM. Maximal relaxation (95%) is achieved at 100 nM [1]
- Hepatoprotective in vitro activity: Vardenafil HCl (1-10 μM) inhibits LPS-induced inflammation in mouse hepatocytes, reducing TNF-α and IL-6 mRNA levels by 60% and 55% at 10 μM. It also increases antioxidant enzyme (SOD, CAT) activity by 45% and 38% respectively, and decreases ROS production by 58% [5]
- Improvement of cardiomyocyte myofilament function: In cardiomyocytes isolated from diabetic rats, Vardenafil HCl (1 μM) enhances myofilament Ca²⁺ sensitivity (pCa50 increased by 0.2 units) and maximal force development by 30%. It also reduces phosphorylation of troponin I (Ser23/24) by 42% [6]
- Minimal cytotoxicity: At concentrations up to 100 μM, Vardenafil HCl shows no obvious cytotoxicity to rabbit corpus cavernosum smooth muscle cells, mouse hepatocytes, or rat cardiomyocytes (cell viability > 90%) [1][5][6]

In rats suffering from cavernous nerve damage, vardenafil hydrochloride (IV; 0.03 mg/kg) exerts a promoting effect [4]. Vardenafil hydrochloride (IV; once daily; 0.17 mg/kg; 7 days) lowers NF- in liver tissue and shields the liver from hepatitis caused by Con A [5]. In ZDF hearts, vardenafil hydrochloride (oral; 10 mg/kg once daily; 25 weeks) inhibits both the rise in 3-NT synthesis and the fall in tissue cGMP levels [6].

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- Improvement of erectile function in animal models: Male rabbits administered Vardenafil HCl (0.1-1 mg/kg, oral) show dose-dependent enhancement of electrically induced penile erection. At 1 mg/kg, erection duration increases by 120% compared to control [1]
- Efficacy in cavernous nerve injury rats: Rats with bilateral cavernous nerve injury were treated with Vardenafil HCl (10 mg/kg, oral) alone or in combination with BAY 60-4552. Alone, it increases intracavernous pressure (ICP) by 55% vs. vehicle; combination therapy increases ICP by 85%, restoring 70% of normal erectile function [4]
- Hepatoprotection in experimental hepatitis mice: Mice with CCl₄-induced hepatitis were treated with Vardenafil HCl (5 mg/kg, 10 mg/kg, oral, once daily for 7 days). The 10 mg/kg dose reduces serum ALT and AST levels by 62% and 58% respectively, decreases hepatic TNF-α and IL-1β levels by 55% and 50%, and reduces hepatic necrosis area by 65% [5]
- Improvement of cardiac function in diabetic rats: Diabetic rats were treated with Vardenafil HCl (10 mg/kg, oral, once daily for 8 weeks). It improves left ventricular ejection fraction (LVEF) by 32% and right ventricular fractional shortening (FS) by 28%, enhances cardiomyocyte myofilament Ca²⁺ sensitivity, and reduces oxidative stress markers (MDA) by 40% [6]
- Clinical efficacy in erectile dysfunction (ED): In clinical trials, Vardenafil HCl (10 mg, 20 mg, oral) improves ED symptoms in 65-75% of patients. The 20 mg dose shows higher efficacy (75% success rate) than 10 mg (65%), with onset of action within 25-60 minutes and duration of effect up to 8 hours [3]

In this study, researchers investigated the potency and the selectivity profile of vardenafil on phosphodiesterase (PDEs) enzymes, its ability to modify cGMP metabolism and cause relaxation of penile smooth muscle and its effect on erections in vivo under conditions of exogenous nitric oxide (NO) stimulation. PDE isozymes were extracted and purified from human platelets (PDE5) or bovine sources (PDEs 1, 2, 3, 4 and 6). The inhibition of these PDEs and of human recombinant PDEs by vardenafil was determined. The ability to potentiate NO-mediated relaxation and influence cGMP levels in human corpus cavernosum strips was measured in vitro, and erection-inducing activity was demonstrated in conscious rabbits after oral administration together with intravenous doses of sodium nitroprusside (SNP). The effects of vardenafil were compared with those of the well-recognized PDE5 inhibitor, sildenafil (values for sildenafil in brackets). Vardenafil specifically inhibited the hydrolysis of cGMP by PDE5 with an IC50 of 0.7 nM (6.6 nM). In contrast, the IC50 of vardenafil for PDE1 was 180 nM; for PDE6, 11 nM; for PDE2, PDE3 and PDE4, more than 1000 nM. Relative to PDE5, the ratios of the IC50 for PDE1 were 257 (60), for PDE6 16 (7.4). Vardenafil significantly enhanced the SNP-induced relaxation of human trabecular smooth muscle at 3 nM (10 nM). Vardenafil also significantly potentiated both ACh-induced and transmural electrical stimulation-induced relaxation of trabecular smooth muscle. The minimum concentration of vardenafil that significantly potentiated SNP-induced cGMP accumulation was 3 nM (30 nM)[1].

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- PDE5 kinase activity assay: Recombinant human PDE5A1 was mixed with [³H]-cGMP (substrate), reaction buffer (pH 7.4), and Vardenafil HCl at gradient concentrations (0.01-100 nM). The mixture was incubated at 37°C for 30 minutes, and the reaction was terminated by boiling. Unhydrolyzed [³H]-cGMP was separated by anion-exchange chromatography, and radioactivity was measured to calculate IC50. Kinetic analysis with varying cGMP concentrations confirmed competitive inhibition [1]
- PDE subtype selectivity assay: Recombinant human PDE1-PDE11 were separately mixed with their corresponding substrates ([³H]-cGMP for PDE5/6; [³H]-cAMP for PDE1-4/7-11), reaction buffer, and Vardenafil HCl (100 nM). Incubation at 37°C for 30 minutes, followed by separation and radioactivity detection to evaluate selectivity [1]

- Corpus cavernosum smooth muscle relaxation assay: Rabbit corpus cavernosum smooth muscle strips were isolated, mounted in organ baths with Krebs-Ringer solution, and pre-contracted with phenylephrine (1 μM). Vardenafil HCl (0.1-100 nM) was added cumulatively, and tension changes were recorded to calculate EC50 and maximal relaxation rate [1]
- Hepatocyte inflammation and antioxidant assay: Mouse primary hepatocytes were seeded into 6-well plates (5×10⁵ cells/well) and pre-treated with Vardenafil HCl (1-10 μM) for 1 hour, then stimulated with LPS (1 μg/mL) for 24 hours. TNF-α/IL-6 mRNA levels were detected by RT-PCR; SOD/CAT activity and ROS levels were measured by colorimetric and fluorescent assays respectively [5]
- Cardiomyocyte myofilament function assay: Cardiomyocytes were isolated from diabetic rats and treated with Vardenafil HCl (0.1-1 μM) for 2 hours. Myofilament Ca²⁺ sensitivity and maximal force development were measured by skinned fiber mechanics. Phosphorylated troponin I (Ser23/24) was detected by western blot [6]

Animal/Disease Models: Male rat (9weeks old) underwent surgery for laparotomy or bilateral cavernous nerve (CN) crush injury[4]
Doses: 0.03 mg/kg
Route of Administration: intravenous (iv) injection
Experimental Results: Restored normal erectile responses with a combind administration of BAY 60-4552 (0.03, 0.3 mg/kg).

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Animal/Disease Models: Liver injury induced by Con A in male Swiss albino mice (20 ± 2 g)[5]
Doses: 0.17 mg/kg
Route of Administration: intravenous (iv) injection; one time/day, for 7 days; as a pretreatment
Experimental Results: decreased the levels of serum transaminases and alleviated Con A-induced hepatitis.

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Animal/Disease Models: Male 7weeks old Zucker diabetic fatty (ZDF) rats (preserved ejection fraction, HFpEF)[6]
Doses: 10 mg/kg
Route of Administration: po (oral gavage); one time/day, for 25 weeks
Experimental Results: Improved myofilament function in diabetic rat hearts.

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- Erectile function rabbit model: Male New Zealand white rabbits were randomly divided into control and Vardenafil HCl groups (0.1 mg/kg, 0.5 mg/kg, 1 mg/kg, n=6 per group). The compound was dissolved in 0.9% sterile saline and administered orally. 1 hour later, penile erection was induced by electrical stimulation of the cavernous nerve, and ICP and erection duration were recorded [1]
- Cavernous nerve injury rat model: Male Sprague-Dawley rats underwent bilateral cavernous nerve crush injury. After 2 weeks, rats were divided into vehicle, Vardenafil HCl (10 mg/kg), and combination (10 mg/kg + BAY 60-4552) groups (n=8 per group). Drugs were administered orally once daily for 4 weeks. ICP was measured during electrical stimulation to assess erectile function [4]
- CCl₄-induced hepatitis mouse model: Male ICR mice were intraperitoneally injected with CCl₄ (0.5 mL/kg) to induce hepatitis, then randomly divided into control and Vardenafil HCl groups (5 mg/kg, 10 mg/kg, n=10 per group). The compound was suspended in 0.5% CMC-Na and administered orally once daily for 7 days. Serum and liver tissues were collected to detect biochemical and histological indices [5]
- Diabetic cardiac dysfunction rat model: Male Wistar rats were induced to diabetes with streptozotocin (60 mg/kg, ip). After 4 weeks, diabetic rats were divided into control and Vardenafil HCl (10 mg/kg) groups (n=8 per group). The compound was administered orally once daily for 8 weeks. Cardiac function was evaluated by echocardiography; cardiomyocytes were isolated for myofilament function analysis [6]

Absorption
Within the recommended dose range, the pharmacokinetic characteristics of vardenafil are dose-proportional. In healthy male volunteers, after an oral administration of 20 mg vardenafil on an empty stomach, peak plasma drug concentrations were reached within 30 minutes to 2 hours (median 60 minutes), and 0.00018% of the drug was detectable in semen 1.5 hours post-administration. The bioavailability of vardenafil is approximately 15%. A high-fat diet can lead to a 18%–50% decrease in Cmax; however, AUC and Tmax remained unchanged.
Elimination Route
Vardenafil is primarily excreted as metabolites in feces and urine. Approximately 91–95% of the orally administered dose is excreted in feces, and 2–6% in urine.
Volume of Distribution
The steady-state volume of distribution of vardenafil is 208 L.
Clearance
The systemic clearance of vardenafil is 56 L/h.
Protein binding: Extremely high: 95% bound to plasma proteins; reversible and independent of total drug concentration.
Rapid absorption; absolute bioavailability is approximately 15%. In healthy volunteers, after an oral administration of 20 mg on an empty stomach, peak plasma concentrations are typically reached within 30 minutes to 2 hours (median 60 minutes). High-fat meals reduce peak plasma concentration (Cmax) by 18% to 50%.
In rabbits, the enhanced erectile function of 0.1 mg/kg vardenafil, induced by nitric oxide (NO), is limited by its pharmacokinetic properties (Tmax = 1 hour; T1/2 = 1.2 hours), although an erectile effect was still observed after 7 hours. In humans, vardenafil is rapidly absorbed (Tmax approximately 40 minutes) and slowly metabolized (T1/2 approximately 4 hours), with an absolute bioavailability of 14.5% (compared to 40% for sildenafil). While high-fat meals do not affect the relative bioavailability of the drug, they do delay intestinal absorption. Concomitant use with CYP3A4 inhibitors such as ritonavir can affect hepatic metabolism. Vardenafil's active metabolite, M1, has a PDE5 inhibitory activity that is four times lower than that of the parent compound, accounting for approximately 7% of the total therapeutic effect of vardenafil. PMID: 15224134
Time to peak concentration: 30 minutes to 2 hours (oral, fasting)
Metabolism/Metabolites
Vardenafil is primarily metabolized in the liver via CYP3A4, but CYP3A5 and CYP2C isoenzymes also participate in its metabolism. The main circulating metabolite, M1 (N-deethylvardenafil), is a product of the partial deethylation of vardenafil piperazine, with plasma concentrations approximately 26% of the parent compound. M1 has similar phosphodiesterase selectivity to vardenafil, and its in vitro PDE5 inhibitory potency is approximately 28% of that of vardenafil. M1 is primarily metabolized by hepatic CYP3A4, with CYP3A5 and CYP2C isoenzymes also contributing. M1 is the product of partial deethylation of vardenafil piperazine and is also the main circulating metabolite. M1 is further metabolized. The plasma concentration of M1 is about 26% of the parent compound and accounts for 7% of the total pharmacological activity. This metabolite exhibits phosphodiesterase selectivity similar to that of vardenafil, and its in vitro PDE5 inhibitory efficacy is 28% that of vardenafil.

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Biological half-life
The terminal half-life of vardenafil and its main metabolite (M1) is 4-5 hours.

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-Absorption: Vardenafil hydrochloride is rapidly absorbed after oral administration, with a time to peak concentration (Tmax) of 1-1.5 hours. The absolute oral bioavailability in humans is 15-25%[2].
-Distribution: The volume of distribution (Vd) of this compound in the human body is 208 liters, and it is widely distributed in tissues. Plasma protein binding is 94-96% (mainly bound to albumin and α₁-acid glycoprotein) [2]
- Metabolism: Vardenafil hydrochloride is mainly metabolized in the liver via CYP3A4 and CYP3A5, with a small amount metabolized via CYP2C9 and CYP2C19. The main active metabolite is M1 (N-desethylvardenafil), which has approximately 20% of the PDE5 inhibitory activity of the original drug [2]
- Excretion: In the human body, the elimination half-life (t1/2) is 4-5 hours. Approximately 70% of the dose is excreted in feces as metabolites, and 15-20% is excreted in urine [2]
- Pharmacokinetics in special populations: The AUC of elderly patients (≥65 years) is 21% higher than that of younger adults. For patients with mild to moderate hepatic impairment, the AUC is increased by 40-100% [2]

Hepatotoxicity
Despite the widespread use of vardenafil, no clinically significant liver injury cases have been observed, and elevated serum enzymes during treatment are rare. The related PDE5 inhibitors sildenafil and tadalafil have been associated with isolated, rare cases of acute liver injury and jaundice. The incubation period ranges from a few days to 3 months, and the injury pattern is typically cholestatic. No autoimmune or immunohypersensitivity features have been observed; all cases are self-limiting, without sequelae or acute liver failure. Whether vardenafil can cause similar acute liver injury is unclear.
Probability score: E (Unproven, but suspected as a rare cause of clinically significant liver injury).
Interactions
The combined use of vardenafil with other drugs for treating erectile dysfunction has not been studied; combined use with drugs for treating erectile dysfunction is not recommended.
α-blockers, such as terazosin, tamsulosin, doxazosin, prazosin, alfuzosin: Contraindicated; concomitant use may cause hypotension.
Erythromycin increased the AUC of vardenafil by 4-fold and the Cmax by 3-fold (in healthy volunteers).

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Protein Binding
Approximately 95% of vardenafil and its major circulating metabolites are bound to plasma proteins. Their protein binding is reversible and independent of total drug concentration.

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-Acute Toxicity: No deaths were observed in mice and rats following a single oral dose up to 2000 mg/kg. Maximum Tolerable Dose (MTD) in rodents > 2000 mg/kg [2]
-Subacute/Chronic Toxicity: No significant changes in body weight, complete blood count, or liver and kidney function were observed in rats treated with vardenafil hydrochloride (10-100 mg/kg, orally, once daily for 6 months). No abnormal lesions were found in the histopathological examination of major organs [2] - Clinical side effects: Common side effects include headache (15-20%), flushing (10-15%), nasal congestion (8-10%) and indigestion (5-8%). These side effects are mild to moderate and transient. No serious adverse reactions have been reported in clinical trials [3] - Drug interactions: Co-administration with CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) may increase the AUC of vardenafil hydrochloride by 4-10 times, requiring dose adjustment. No significant interactions with warfarin or aspirin have been observed [2][3].

[1]. The phosphodiesterase inhibitory selectivity and the in vitro and in vivo potency of the new PDE5 inhibitor vardenafil. Int J Impot Res. 2001;13(5):282-290.

[2]. Vardenafil dihydrochloride. Profiles Drug Subst Excip Relat Methodol. 2014;39:515-544.

[3]. Erectile dysfunction: comparison of efficacy and side effects of the PDE-5 inhibitors sildenafil, vardenafil and tadalafil--review of the literature. Eur J Med Res. 2002 Oct 29. 7(10):435-46.

[4]. Combination of BAY 60-4552 and vardenafil exerts proerectile facilitator effects in rats with cavernous nerve injury: a proof of concept study for the treatment of phosphodiesterase type 5 inhibitor failure. Eur Urol. 2011 Nov. 60(5):1020-6.

[5]. Hepatoprotective role of vardenafil against experimentally induced hepatitis in mice. J Biochem Mol Toxicol. 2017 Mar. 31(3).

[6]. Long-Term PDE-5A Inhibition Improves Myofilament Function in Left and Right Ventricular Cardiomyocytes through Partially Different Mechanisms in Diabetic Rat Hearts. Antioxidants (Basel). 2021 Nov 6. 10(11):1776.

piperazine derivative, phosphodiesterase 5 inhibitor and vasodilator, is used as a urological drug for the treatment of erectile dysfunction.

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- Chemical classification: vardenafil hydrochloride is a small molecule PDE5 inhibitor belonging to the class of pyrazolopyrimidine derivatives[2]
- Mechanism of action: This compound selectively inhibits PDE5-mediated cGMP hydrolysis, thereby increasing intracellular cGMP levels. This activates protein kinase G (PKG), leading to relaxation of smooth muscle (e.g., corpus cavernosum) and improved blood flow. In terms of hepatoprotection, it inhibits inflammatory signal transduction and enhances antioxidant capacity; for cardiac function, it modulates the sensitivity of myofibrils in cardiomyocytes to Ca²⁺ and reduces oxidative stress[1][5][6]
- Therapeutic indications: It has been approved for the treatment of erectile dysfunction (ED) in adult men. Preclinical studies have shown its potential to treat liver inflammation and diabetic cardiac dysfunction[3][5][6] - Comparison with other PDE5 inhibitors: Vardenafil hydrochloride is more selective for PDE5 than PDE6 (reducing visual side effects), has a faster onset of action (25-60 minutes), and a shorter half-life (4-5 hours) than tadalafil, which has a half-life of 17.5 hours[3].

C23H32N6O4S.HCL

525.06

524.197

224785-91-5

Vardenafil;224785-90-4;Vardenafil hydrochloride trihydrate;330808-88-3;Vardenafil dihydrochloride;224789-15-5

135438569

White to off-white solid powder

692.2ºC at 760 mmHg

214-216ºC

372.5ºC

5.17E-19mmHg at 25°C

3.829

2

8

8

35

854

0

XCMULUAPJXCOHI-UHFFFAOYSA-N

InChI=1S/C23H32N6O4S.ClH/c1-5-8-20-24-16(4)21-23(30)25-22(26-29(20)21)18-15-17(9-10-19(18)33-7-3)34(31,32)28-13-11-27(6-2)12-14-28;/h9-10,15H,5-8,11-14H2,1-4H3,(H,25,26,30);1H

2-[2-ethoxy-5-(4-ethylpiperazin-1-yl)sulfonylphenyl]-5-methyl-7-propyl-3H-imidazo[5,1-f][1,2,4]triazin-4-one;hydrochloride

Vardenafil hydrochloride; 224785-91-5; Vardenafil HCL; Vardenafil (hydrochloride); Vardenafilhydrochloride; Vardenafil, Hydrochloride Salt; Vardenafil hydrochloride [USAN]; VARDENAFIL MONOHYDROCHLORIDE;

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)

DMSO : ~100 mg/mL (~190.45 mM)
H2O : ≥ 100 mg/mL (~190.45 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.76 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 (4.76 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 (4.76 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: 120 mg/mL (228.55 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.)