Letrozole 2.5 mg

Letrozole is a synthetic small molecule belonging to the class of non-steroidal enzyme inhibitors, chemically a triazole with two benzonitrile substituents. In scientific research, it is studied as a model compound for coordinating, reversible enzyme inhibition and as a reference standard in analytical work. This compound is offered as 2.5 mg tablets, exclusively for laboratory and research purposes.

What is Letrozole?

Letrozole (4-[(4-cyanophenyl)-(1,2,4-triazol-1-yl)methyl]benzonitrile) consists of a central methine carbon atom holding together a 1,2,4-triazole ring and two identical 4-cyanophenyl groups. Because both aryl rings are identical, the molecule is symmetrical and therefore achiral: there are no enantiomers that need to be separated, making the compound a straightforward reference substance. Additionally, the two nitrile groups ensure strong absorption in the ultraviolet region and a highly predictable fragmentation pattern in mass spectrometry.

In research models, the action of Letrozole is based on coordination chemistry: a ring nitrogen of the triazole binds to the heme iron in the active cavity of the enzyme aromatase (CYP19A1), thereby reversibly displacing the natural substrate. Because no covalent bond is formed, the enzyme becomes available again after dilution, causing the compound to exhibit competitive inhibition kinetics in vitro with an exceptionally low inhibition constant. This property makes it a widely used positive control in enzyme inhibition assays. Accordingly, Letrozole is used as a model compound and reference substance in scientific research.

Research areas

In a laboratory context, Letrozole occurs in the following research areas, among others:

• Enzyme kinetic research into competitive, reversible inhibition of CYP19A1 in microsome models.
• In vitro selectivity study of cross-reactivity with other cytochrome P450 isoforms.
• Coordination chemistry study of the binding of azole nitrogen to heme iron, followed by spectral shift of the heme band.
• Research into steroid conversion in cell culture systems, monitored via the conversion products in the culture medium.
• Analytical method development and validation (HPLC with UV detection, LC-MS) using Letrozole as the calibration substance and positive control.
• Stability and solubility studies of nitrile-substituted azole compounds under controlled conditions.

Each of these applications involves controlled laboratory or preclinical model research.

Letrozole in our research assortment

Letrozole falls under the category of oral investigational compounds in solid tablet form within our range. Researchers working with this category regularly place the compound alongside other small molecules that are studied via their own biochemical target. While Letrozole focuses on reversible, metal-coordinated enzyme inhibition, other components within the same product line have been specifically chosen to cover irreversible enzyme inactivation or receptor-linked targets. These compounds share the solid tablet form and the standardized amount of active substance per unit, but differ fundamentally in molecular class and the mechanism under investigation.

Specifications

Shape, handling and storage

Letrozole is supplied as solid tablets with a standardized amount of 2.5 mg per tablet, packaged in units of 100. Because the active substance content per unit is low, in analytical work a number of tablets are usually processed together and dissolved in a suitable analytical medium so that the determination falls within the reliable part of the calibration curve. The compound is moderately water-soluble and mixes well with polar organic media.

Store the tablets dry at room temperature, protected from direct light and moisture, in the original packaging. The triazole ring is chemically stable, but moisture can degrade the tablet matrix, affecting the uniform distribution of the active substance. Handle the compound with standard laboratory precautions: work in a clean environment, use appropriate personal protective equipment, and prevent cross-contamination with other research materials. Keep the packaging out of reach of unauthorized persons.

Composition and lab results

For this compound, the content is expressed as the amount of active substance per tablet (2.5 mg per tablet) rather than as a purity percentage, as is customary for tablet and capsule formulations. In the case of a low unit content, it is precisely the uniformity of that distribution that is the determining specification.

You can find an overview of the available analytical documentation on our lab results pageThe reports are collected centrally there, so that you can incorporate the data into your own research records.

Frequently Asked Questions

To which substance class does Letrozole belong?
Letrozole is a synthetic small molecule of the non-steroidal triazole series and is classified as a reversible aromatase inhibitor of type II. It is not a peptide and therefore contains no amino acid sequence.

Why is the triazole ring decisive for the mechanism?
One of the ring nitrogens of the triazole coordinates to the heme iron in the active cavity of CYP19A1. This coordination bond is strong but not covalent, making the inhibition competitive and reversible in vitro. This distinguishes the compound from steroidal inactivators, which form a permanent covalent bond.

In what form is the compound supplied?
As solid tablets with 2.5 mg of active substance per tablet, packed in units of 100.

How do I store the tablets?
Dry, at room temperature and protected from light and moisture, preferably in the original packaging.