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Tadalafil structure
Tadalafil structure


Iupac Name:(2R,8R)-2-(1,3-benzodioxol-5-yl)-6-methyl-3,6,17-triazatetracyclo[,8.011,16]heptadeca-1(10),11,13,15-tetraene-4,7-dione
CAS No.:171596-29-5
Molecular Weight:389.411
Introduction: Tadalafil (market name “Cialis” or “Adcirca”) is a kind of PDE5 inhibitor used for the treatment of erectile dysfunction, benign prostatic hypertrophy and pulmonary arterial hypertension. The effect of Tadalafil is relaxing the blood vessels muscles and increasing the blood flow into the corpus cavernosum. The mechanism of action of tadalafil is through inhibiting the activity of the cGMP specific phosphodiesterase type 5 (PDE5). PDE5 degrades cGMP in the corpus cavernosum located around the penis. Therefore, tadalafi leads to the increased concentration of cGMP which further causes the smooth muscle relaxation and increased blood flow into the corpus cavernosum. Some clinical studies also implied that tadalafil could improve endothelia function in men with increased cardiovascular risk and lower the urinary tract symptoms secondary to benign prostatic hyperplasia.
1. Names and Identifiers
1.1 Name
1.2 Synonyms

(6R,12AR)-6-(benzo[d][1,3]dioxol-5-yl)-2-methyl-2,3,12,12a-tetrahydropyrazino[1',2':1,6]pyrido GF 196960 IC 351 ICOS 351 Tildenafil UK 336017

1.3 CAS No.
1.4 CID
1.6 Molecular Formula
C22H19N3O4 (isomer)
1.7 Inchi
1.8 InChkey
1.9 Canonical Smiles
1.10 Isomers Smiles
2. Properties
3.1 Density
3.2 Melting Point
3.3 Boiling Point
679.1oC at 760 mmHg
3.4 Vapour
5.29E-13mmHg at 25°C
3.5 Refractive Index
3.6 Flash Point
3.7 Alpha
D20 +71.0°
3.8 Appearance
Off-White Cyrstalline Solid
3.9 Chemical Properties
White to Off-White Cyrstalline Solid
3.10 Color/Form
3.11 Physical
3.12 pKa
3.13 Solubility
DMSO: soluble20mg/mL, clear
3.14 StorageTemp
Hygroscopic, -20?C Freezer, Under Inert Atmosphere
3.15 Water Solubility
In water, 220 mg/L at 25 deg C /Estimated/
3. Use and Manufacturing
4.1 Definition
ChEBI: A pyrazinopyridoindole that is 2,3,6,7,12,12a-hexahydropyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione substituted at position 2 by a methyl group and at position 6 by a 1,3-benzodioxol-5-yl group (the 6R,12aR
4.2 GHS Classification
Signal: Warning
GHS Hazard Statements
Aggregated GHS information provided by 65 companies from 6 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

H302 (58.46%): Harmful if swallowed [Warning Acute toxicity, oral]
H312 (56.92%): Harmful in contact with skin [Warning Acute toxicity, dermal]
H315 (38.46%): Causes skin irritation [Warning Skin corrosion/irritation]
H319 (36.92%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]
H332 (56.92%): Harmful if inhaled [Warning Acute toxicity, inhalation]
H335 (35.38%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown.

Precautionary Statement Codes
P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P312, P321, P322, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, and P501
4.3 Usage
Cialis (or Tadalafil) was developed by American pharmaceutical company Lilly. It is used to treat erectile dysfunction and belongs to a second generation of PDE5 inhibitors. Studies show that Cialis works very quickly, taking effect in around 15-20 minutes, and has a prolonged effect that can last for up to 36 hours. T1/2 is 17.5h.
4. Safety and Handling
5.1 Hazard Codes
5.2 Risk Statements
5.3 Safety Statements
5.4 Transport
UN 1648 3 / PGII
5.5 DisposalMethods
SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.
5.6 Exposure Standards and Regulations
The Approved Drug Products with Therapeutic Equivalence Evaluations List identifies currently marketed prescription drug products, incl tadalafil, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act.
5.7 Formulations/Preparations
Oral: Tablets, film-coated: 5 mg (Cialis), (Lilly ICOS); 10 mg (Cialis), (Lilly ICOS); 20 mg (Cialis), (Lilly ICOS).
5.8 Octanol/Water Partition Coefficient
log Kow = 1.42 /Estimated/
5.9 Safety

The most common side effects of tadalafil?are: are headache, indigestion, flushing,back pain, muscle aches and stuffy or runny nose. These side effects reflect the ability of PDE5 inhibition to vasodilate (cause blood vessels to widen), these usually go away after a few hours. Back pain and muscle aches?maybe occur 12 to 24 hours after taking the drug,and the symptom usually disappears after 48 hours.

5.10 Specification

?Tadalafil? (CAS NO.171596-29-5) is the main raw materials of Cialis,compare with?Sildenafil,Tadalafil have less side effects, after taking two days,30% of people have muscles ache feeling (mainly waist and legs). It is also called as Tadalafil [USAN]?; (6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-methyl-6-(3,4-(methylenedioxy)phenyl) pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione ; (6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione ; (6R-trans)-6-(1,3-Benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione ; Adcirca ; Cialis ; Tadalafil ; Tadalafil Lilly ;Pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione, 6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-, (6R,12aR)- ; Pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione, 6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-, (6R-trans)- .


2.Hazard identification

2.1 Classification of the substance or mixture

Acute toxicity - Oral, Category 4

Acute toxicity - Dermal, Category 4

Acute toxicity - Inhalation, Category 4

2.2 GHS label elements, including precautionary statements

Signal word


Hazard statement(s)

H302 Harmful if swallowed

H312 Harmful in contact with skin

H332 Harmful if inhaled

Precautionary statement(s)

P264 Wash ... thoroughly after handling.

P270 Do not eat, drink or smoke when using this product.

P280 Wear protective gloves/protective clothing/eye protection/face protection.

P261 Avoid breathing dust/fume/gas/mist/vapours/spray.

P271 Use only outdoors or in a well-ventilated area.


P301+P312 IF SWALLOWED: Call a POISON CENTER/doctor/…if you feel unwell.

P330 Rinse mouth.

P302+P352 IF ON SKIN: Wash with plenty of water/...

P312 Call a POISON CENTER/doctor/…if you feel unwell.

P321 Specific treatment (see ... on this label).

P362+P364 Take off contaminated clothing and wash it before reuse.

P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.




P501 Dispose of contents/container to ...

2.3 Other hazards which do not result in classification


8. Computational chemical data
  • Molecular Weight:389.411g/mol
  • Molecular Formula:C22H19N3O4
  • Compound Is Canonicalized:True
  • XLogP3-AA:2.3
  • Exact Mass:389.13755610
  • Monoisotopic Mass:389.13755610
  • Complexity:702
  • Rotatable Bond Count:1
  • Hydrogen Bond Donor Count:1
  • Hydrogen Bond Acceptor Count:4
  • Topological Polar Surface Area:74.9
  • Heavy Atom Count:29
  • Defined Atom Stereocenter Count:2
  • Undefined Atom Stereocenter Count:0
  • Defined Bond Stereocenter Count:0
  • Undefined Bond Stereocenter Count:0
  • Isotope Atom Count:0
  • Covalently-Bonded Unit Count:1
9. Question & Answer
  • Uses Tadalafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, tadalafil works by increasing blood flow to the penis to help a man get and keep an erection. Tadalafil is also used to treat the symptoms of an enlarged pro...
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