PDE5 (IC50 = 90 nM)

PDE5 is inhibited by cis-tadalafil (compound 12b) at an IC50 of 0.09 μM [1].

Interactions
Simultaneous administration of an antacid (magnesium hydroxide/aluminum hydroxide) and tadalafil reduced the apparent rate of absorption of tadalafil without altering the exposure (AUC) to tadalafil.
A significant interaction between tadalafil and nitroglycerin was observed to last up to 48 hours; at least 48 hours should elapse after the last dose of tadalafil before nitrate administration is considered.
Administration of tadalafil to patients who are using any form of organic nitrates, either regularly and/or intermittently, is contraindicated; in clinical pharmacology studies tadalafil was shown to potentiate the hypotensive effects of nitrates; this is thought to result from the combined effects of nitrates and tadalafil on the nitric oxide/cGMP pathway.
The safety and efficacy of combinations of tadalafil and other erectile dysfunctions have not been studied; use of combinations is not recommended.
For more Interactions (Complete) data for TADALAFIL (15 total), please visit the HSDB record page.

[1]. The discovery of tadalafil: a novel and highly selective PDE5 inhibitor. 2: 2,3,6,7,12,12a-hexahydropyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione analogues. J Med Chem. 2003 Oct 9;46(21):4533-42.

Modification of the hydantoin ring in the previously described lead compound 2a has led to the discovery of compound 12a, tadalafil, a highly potent and highly selective PDE5 inhibitor. The replacement of the hydantoin in compound 2a by a piperazinedione ring led to compound cis-11a which showed similar PDE5 inhibitory potency. Introduction of a 3,4-methylenedioxy substitution on the phenyl ring in position 6 led to a potent PDE5 inhibitor cis-11c with increased cellular potency. Optimization of the chain on the piperazinedione ring led to the identification of the racemic cis-N-methyl derivative 11i. High diastereospecificity for PDE5 inhibition was observed in the piperazinedione series with the cis-(6R,12aR) enantiomer displaying the highest PDE5 inhibitory activity. The piperazinedione 12a, tadalafil (GF196960), has been identified as a highly potent PDE5 inhibitor (IC(50) = 5 nM) with high selectivity for PDE5 vs PDE1-4 and PDE6. Compound 12a displays 85-fold greater selectivity vs PDE6 than sildenafil 1. 12a showed profound and long-lasting blood pressure lowering activity (30 mmHg/>7 h) in the spontaneously hypertensive rat model after oral administration (5 mg/kg).

---

Therapeutic Uses
Tadalafil is indicated for the treatment of erectile dysfunction. /Included in US product labeling/

---

Drug Warnings
The Food and Drug Administration ... approved updated labeling for Cialis, Levitra and Viagra to reflect a small number of post-marketing reports of sudden vision loss, attributed to NAION (non arteritic ischemic optic neuropathy), a condition where blood flow is blocked to the optic nerve. FDA advises patients to stop taking these medicines, and call a doctor or healthcare provider right away if they experience sudden or decreased vision loss in one or both eyes. Further, patients taking or considering taking these products should inform their health care professionals if they have ever had severe loss of vision, which might reflect a prior episode of NAION. Such patients are at an increased risk of developing NAION again.
Cardiovascular status of patients should be considered since there is a degree of risk associated with sexual activity; treatments for erectile dysfunction, including tadalafil, should not be used in men for whom sexual activity is inadvisable as a result of their underlying cardiac status.
The following groups of patients with cardiovascular disease were not included in clinical safety and efficacy trials for Cialis, and, therefore, the use of Cialis is not recommended in these groups until further information is available: patients with a myocardial infarction within the last 90 days, patients with unstable angina or angina occurring during sexual intercourse, patients with New York Heart Association Class 2 or greater heart failure in the last 6 months, patients with uncontrolled arrhythmias, hypotension (<90/50 mm Hg), or uncontrolled hypertension (>170/100 mm Hg), and patients with a stroke within the last 6 months. In addition, patients with known hereditary degenerative retinal disorders, including retinitis pigmentosa, were not included in the clinical trials, and use in these patients is not recommended.
The effect of a 100 mg single dose of tadalafil on the QT interval was evaluated at the time of peak tadalafil concentration in a randomized, double-blinded, placebo, and active (intravenous ibutilide)-controlled crossover study in 90 healthy males aged 18 to 53 years. The mean change in QTc (Fridericia QT correction) for tadalafil, relative to placebo, was 3.5 milliseconds (two-sided 90% CI=1.9, 5.1). The mean change in QTc (Individual QT correction) for tadalafil, relative to placebo, was 2.8 milliseconds (two-sided 90% CI=1.2, 4.4). A 100 mg dose of tadalafil (5 times the highest recommended dose) was chosen because this dose yields exposures covering those observed upon coadministration of tadalafil with potent CYP3A4 inhibitors or those observed in renal impairment. In this study, the mean increase in heart rate associated with /this/ dose of tadalafil compared to placebo was 3.1 beats per minute.
For more Drug Warnings (Complete) data for TADALAFIL (18 total), please visit the HSDB record page.

---

Pharmacodynamics
Tadalafil exerts a therapeutic effect in ED by increasing sexual stimulation-dependant smooth muscle relaxation in the penis, allowing the corpus cavernosum to fill with blood to produce an erection. Smooth muscle relaxation in the pulmonary vasculature helps to produce vasodilation in PAH which reduces blood pressure in the pulmonary arteries. In BPH, tadalafil may contribute to decreased smooth muscle cell proliferation which may reduce the size of the prostate and relieve the anatomical obstruction which produces urinary symptoms of BPH. The decreased affinity of tadalafil for PDE6 compared to other PDE5 inhibitors may explain the reduced incidence of visual side effects.

C22H19N3O4

389.40396

389.138

C, 67.86; H, 4.92; N, 10.79; O, 16.43

171596-27-3

Nortadalafil;171596-36-4;Tadalafil;171596-29-5;ent-Tadalafil;629652-72-8;cis-ent-Tadalafil;171596-28-4;cis-Tadalafil-d3;1329799-70-3;cis-ent-Tadalafil-d3

9821704

Typically exists as solid at room temperature

1.51±0.1 g/cm3 (20 ºC 760 Torr)

295-296 ºC

2.087

1

4

1

29

702

2

CN1CC(=O)N2C(C1=O)CC3=C(C2C4=CC5=C(C=C4)OCO5)NC6=CC=CC=C36

WOXKDUGGOYFFRN-IIBYNOLFSA-N

InChI=1S/C22H19N3O4/c1-24-10-19(26)25-16(22(24)27)9-14-13-4-2-3-5-15(13)23-20(14)21(25)12-6-7-17-18(8-12)29-11-28-17/h2-8,16,21,23H,9-11H2,1H3/t16-,21-/m1/s1

(6R,12aS)-6-(1,3-Benzodioxol-5-yl)-2-methyl-2,3,6,7,12,12a-hexahydropyrazino(1',2'

Tadalafil specified impurity A, 171596-27-3; Tadalafil, (6R ,12aS)-; cis-Tadalafil; Tadalafil 6R ,12as diastereomer; (-)-Tadalafil 6R ,12as diastereomer; CHEMBL139028; E319TQ0B6R; Tadalafil EP Impurity A; Tadalafil (6R ,12aS)- Tadalafil (6R ,12aS)- Lilly

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

---

Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

View More

Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

---

Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

View More

Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

---

Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

---

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