Nortadalafil

Nortadalafil (Demethyltadalafil) Research Standard

Nortadalafil, also referred to as Demethyltadalafil, is a synthetic structural analog of the phosphodiesterase type 5 (PDE5) inhibitor tadalafil. Structurally distinguished by the absence of the N-methyl group on the piperazinedione ring, this compound serves as a critical analytical reference standard. It is extensively utilized in forensic and pharmaceutical laboratories for impurity profiling, as it often appears as a process-related byproduct or an undeclared adulterant in complex matrices. Its high-fidelity chemical profile makes it a vital tool for validating analytical methods and conducting structure-activity relationship (SAR) investigations within the PDE5 inhibitor class.

Physical & Handling Properties

Mechanism of Action & Research Context

Nortadalafil functions as a competitive inhibitor of the PDE5 enzyme, sharing the core pharmacophore of the parent compound tadalafil while possessing distinct binding kinetics due to the structural modification.

• Enzyme Interaction: The presence of the amide bond and the piperazinedione ring allows the molecule to occupy the catalytic site of the PDE5 enzyme. Its structural configuration—featuring multiple hydrogen bond donors and acceptors—enables it to compete effectively with cyclic guanosine monophosphate (cGMP) in binding pockets.

• Impurity Profiling: Because nortadalafil is a known process-related impurity in the synthesis of tadalafil, it is indispensable for pharmaceutical compliance testing, ensuring that generic manufacturing processes remain within regulatory thresholds for purity.

• Structural Comparison: The benzodioxole ring contributes to its three-dimensional conformation, and researchers use this compound to compare how the absence of the N-methyl group alters steric hindrance and binding affinity relative to tadalafil.

Research Applications

Nortadalafil is a specialized reagent essential for analytical validation and toxicological screening.

Primary fields of in vitro laboratory investigation include:

• Binding Studies: Utilizing isolated PDE5 enzyme preparations and competitive displacement assays to quantify the binding affinity of nortadalafil versus radiolabeled ligands.

• Impurity Profiling: Mapping and identifying synthesis by-products in tadalafil drug substances to satisfy pharmacopoeial monograph compliance.

• Forensic Screening: Acting as a certified reference standard for LC-MS/MS methods to identify undeclared PDE5 inhibitors in complex dietary supplement samples.

• SAR Analysis: Serving as a baseline tool to study how subtle demethylation influences chromatographic retention times and mass spectral fragmentation patterns.

Storage & Handling Guidelines

Store at controlled room temperature. Keep tightly closed. Liquid formats: do not refrigerate or freeze. Cold storage may cause the solution to cloud or precipitate. If this occurs, return to room temperature and mix until clear.

Storage guidance is a house recommendation. Analytical documentation is per-lot release testing.

References

• BenchChem. (2026) Nortadalafil (CAS 171596-36-4) | PDE5 Inhibitor Impurity Ref. Standard.

• Synthink Research Chemicals. (2026) Tadalafil EP Impurities & USP Related Compounds.

• Creative Enzymes. (2026) Nortadalafil Product Overview.

Related Research Compounds

• Mirodenafil
• N-ethyl Tadalafil
• N-Isopropyl Tadalafil
• Acetildenafil

Research Use Disclaimer

Research Use Only Disclaimer: This product is labeled and sold "For Research Use Only — NOT FOR HUMAN CONSUMPTION." It is not a drug, dietary supplement, food, cosmetic, or medical device, and it is not approved by the FDA or any other regulator for human or veterinary use. It is supplied to approved account holders as a research chemical for laboratory use and must be handled in accordance with applicable law.