Tadalafil Impurities

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Impurity structure Parent Drug Name Name of Impurity Catalogue No. CAS No.
Methyl (1R,3R)-2-acetyl-1-(benzo[d][1,3]dioxol-5-yl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylate Tadalafil

Methyl (1R,3R)-2-acetyl-1-(benzo[d][1,3]dioxol-5-yl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylate

VE0018061 1598416-05-7
N-Butyl Tadalafil Tadalafil

N-Butyl Tadalafil

VE0018713 171596-31-9
N-Desmethyl epi-Tadalafil Tadalafil

N-Desmethyl epi-Tadalafil

VE0018749 929100-66-3
N-Ethyl Tadalafil Tadalafil

N-Ethyl Tadalafil

VE0018614 1609405-34-6
N-Isopropyl Tadalafil Tadalafil

N-Isopropyl Tadalafil

VE0018718 171596-30-8
N-Nitroso Tadalafil Tadalafil

N-Nitroso Tadalafil

VE0015849 N/A
N-Octyl-Nortadalafil Tadalafil


VE0018711 1173706-35-8
N-Phenylpropenyl Tadalafil Tadalafil

N-Phenylpropenyl Tadalafil

VE0018712 2064212-00-4
Nor-Tadalafil Tadalafil


VE0018719 171596-36-4
Tadalafil (1S-cis) Methyl Ester Impurity Tadalafil

Tadalafil (1S-cis) Methyl Ester Impurity

VE000013 171596-43-3
Tadalafil Chloroacetyl Impurity Tadalafil

Tadalafil Chloroacetyl Impurity

VL300009 N/A
Tadalafil Dichloro Impurity Tadalafil

Tadalafil Dichloro Impurity

VE0018203 1598416-08-0
Tadalafil Dimethoxy Impurity Tadalafil

Tadalafil Dimethoxy Impurity

VE0018627 1356345-67-9
Tadalafil EP Impurity A Tadalafil

Tadalafil EP Impurity A

VL300003 171596-27-3
Tadalafil EP Impurity B Tadalafil

Tadalafil EP Impurity B

VL300008 629652-72-8
Tadalafil EP Impurity C Tadalafil

Tadalafil EP Impurity C

VL300002 171596-28-4
Tadalafil EP Impurity D Tadalafil

Tadalafil EP Impurity D

VE0013755 N/A
Tadalafil EP Impurity E Tadalafil

Tadalafil EP Impurity E

VE0011984 1978322-99-4
Tadalafil EP Impurity F Tadalafil

Tadalafil EP Impurity F

VE0011467 2747958-44-5
Tadalafil EP Impurity G Tadalafil

Tadalafil EP Impurity G

VE0011985 531500-48-8
Tadalafil EP Impurity H Tadalafil

Tadalafil EP Impurity H

VE0011986 1346605-38-6
Tadalafil EP Impurity I Tadalafil

Tadalafil EP Impurity I

VE0011987 1795790-92-9
Tadalafil Impurity 1 Tadalafil

Tadalafil Impurity 1

VE0017648 171752-68-4
Tadalafil Impurity 10 Tadalafil

Tadalafil Impurity 10

VE0020303 2058231-15-3
Tadalafil Impurity 13 Tadalafil

Tadalafil Impurity 13

VE0018741 1370438-57-5
Tadalafil Impurity 14 Tadalafil

Tadalafil Impurity 14

VE0018743 N/A
Tadalafil Impurity 18 Tadalafil

Tadalafil Impurity 18

VE0017755 2169996-11-4
Tadalafil Impurity 20 Tadalafil

Tadalafil Impurity 20

VE0018635 406938-39-4
Tadalafil Impurity 24 Tadalafil

Tadalafil Impurity 24

VE0011983 951661-81-7
Tadalafil Impurity 25 (Mixture of Diastereomers) Tadalafil

Tadalafil Impurity 25 (Mixture of Diastereomers)

VE0018747 N/A
Tadalafil Impurity 38 Tadalafil

Tadalafil Impurity 38

VE0018460 185750-07-6
Tadalafil Impurity 57 Tadalafil

Tadalafil Impurity 57

VE0018313 N/A
Tadalafil Impurity 59 Tadalafil

Tadalafil Impurity 59

VE0018611 N/A
Tadalafil Impurity 64 Tadalafil

Tadalafil Impurity 64

VE0018612 N/A
Tadalafil Impurity 66 Tadalafil

Tadalafil Impurity 66

VE0018613 1598416-07-9
Tadalafil Impurity 75 Tadalafil

Tadalafil Impurity 75

VE0019747 N/A
Tadalafil Impurity 8 Tadalafil

Tadalafil Impurity 8

VE0018717 1803592-02-0
Tadalafil Impurity 87 Tadalafil

Tadalafil Impurity 87

VE0018617 691871-71-3
Tadalafil Impurity 9 Tadalafil

Tadalafil Impurity 9

VE0018015 951661-82-8
Tadalafil Impurity II Tadalafil

Tadalafil Impurity II

VL300006 N/A
Tadalafil In House Impurity A Tadalafil

Tadalafil In House Impurity A

VL300007 120-57-0
Tadalafil N-Desmethyl N-Amino Tadalafil

Tadalafil N-Desmethyl N-Amino

VE007823 385769-84-6
Tadalafil N-Dipropyl Impurity Tadalafil

Tadalafil N-Dipropyl Impurity

VE0018708 N/A
Tadalafil N-Methyl Tadalafil

Tadalafil N-Methyl

VL300004 477970-21-1
Tadalafil N-Oxide Tadalafil

Tadalafil N-Oxide

VL300005 N/A
Tadalafil Nitroso Impurity 2 Tadalafil

Tadalafil Nitroso Impurity 2

VE0017536 N/A
Tadalafil Nitroso Impurity 3 Tadalafil

Tadalafil Nitroso Impurity 3

VE0017537 N/A
Tadalafil Nitroso Impurity 4 Tadalafil

Tadalafil Nitroso Impurity 4

VE0017538 N/A
Tadalafil Nitroso Impurity 5 Tadalafil

Tadalafil Nitroso Impurity 5

VE0017540 N/A
Tadalafil Related Compound 1 Tadalafil

Tadalafil Related Compound 1

VE0018621 N/A

Tadalafil Related Compound

Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or maintain an erection) and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) in adult men, including difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency.


  • “Tadalafil: MedlinePlus Drug Information.” Medlineplus.gov, 2022, medlineplus.gov/druginfo/meds/a604008.html#:~:text=Tadalafil%20is%20in%20a%20class,the%20penis%20during%20sexual%20stimulation. Accessed 2 Mar. 2023. ‌
  • Grossman, Ehud. “The Role of Tadalafil in Treated Hypertensive Patients with Erectile Dysfunction.” The Journal of Clinical Hypertension, vol. 24, no. 2, Jan. 2022, pp. 182–83, https://doi.org/10.1111/jch.14434. Accessed 2 Mar. 2023. ‌
  • “How Long Does Tadalafil Last? | Hims.” Hims, 2021, www.forhims.com/blog/how-long-does-tadalafil-last#:~:text=Tadalafil%20differs%20from%20other%20PDE5,the%20National%20Library%20of%20Medicine. Accessed 2 Mar. 2023.


What is the therapeutic class of tadalafil?

Tadalafil is part of a class of drugs known as phosphodiesterase (PDE) inhibitors. It works by boosting blood flow to the penis during sexual stimulation to treat erectile dysfunction.

Does tadalafil lower blood pressure?

Tadalafil at a low dose (5 mg daily) can enhance blood pressure regulation and erectile function. The fact that PDE5 inhibitors can decrease blood pressure while also improving erectile function implies that reducing blood pressure does not cause ED and that it is most likely caused by antihypertensive medicines.

How long does tadalafil stay effective?

Tadalafil differs from other PDE5 inhibitors in that it has a much longer duration of action. Unlike Viagra, which only works for a few hours after it is taken, Tadalafil can be effective for up to 36 hours after a single dose.