Atosiban Acetate API (CAS 90779-69-4) Manufacturer | Obstetric-Grade Peptide Synthesis
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⚠️ B2B Compliance & Identity Notice
Shaanxi Sunrise (Pharma-Sunrise) operates strictly as an upstream B2B chemical manufacturer and advanced peptide synthesis facility. The materials discussed herein, including Atosiban Acetate API Powder (CAS 90779-69-4), are raw pharmaceutical ingredients designed exclusively for qualified R&D laboratories, CDMOs, and industrial formulation engineers. We do not manufacture, package, or distribute finished retail intravenous (IV) dosage forms. Not for direct human consumption. No C-end retail inquiries will be entertained.
Obstetrics Leaves No Room for Chemical Ambiguity.
When a CDMO formulates a tocolytic agent, they are not developing a casual topical cream. They are engineering a critical, life-saving intravenous (IV) infusion designed to halt premature labor. The target patients are highly vulnerable pregnant women experiencing acute preterm uterine contractions. In this clinical arena, the API must be flawless. Atosiban Acetate (CAS 90779-69-4)—a highly potent, synthetic cyclic nonapeptide that acts as a competitive antagonist of oxytocin and vasopressin receptors—is the gold standard for this indication in many global pharmacopeias. But step away from the clinical data and step onto the heavy industrial synthesis floor. The reality hits you immediately. Manufacturing this nine-amino-acid ring is a thermodynamic nightmare.
Do not let the short sequence length fool you. Nine amino acids might sound trivial compared to massive GLP-1 analogs. It is not. Atosiban is a cyclic peptide containing heavily modified, unnatural amino acids, consecutive β-branched residues, and a highly precarious disulfide bridge. The global market is currently flooded with opportunistic, low-tier peptide suppliers claiming to have mastered commercial Atosiban production. They haven't. What they are shipping to unsuspecting formulation engineers is often a crude mix of intermolecular dimers, sequence-deletion impurities, and lethal levels of residual Trifluoroacetic Acid (TFA). For an obstetric CDMO auditor, utilizing substandard Atosiban API isn't just a regulatory failure. It is a severe clinical liability. If the API contains agonistic impurities rather than pure antagonistic Atosiban, you risk exacerbating the very uterine contractions you are trying to stop.
The Cyclic Minefield: Why Generic SPPS Architectures Fail
The structural sequence of Atosiban is complex: [Mpa-D-Tyr(Et)-Ile-Thr-Asn-Cys-Pro-Orn-Gly-NH2]. It requires precise Solid-Phase Peptide Synthesis (SPPS) followed by a critical liquid-phase macrocyclization. This is exactly where amateur manufacturers destroy the molecule. The fundamental physics of the reaction turn violently against the chemist.
1. Macrocyclization vs. Intermolecular Dimerization
The functional integrity of Atosiban relies entirely on closing the ring by forming a disulfide bridge between the Mercaptopropionic acid (Mpa) at position 1 and the Cysteine (Cys) at position 6. This oxidation step is a brutal thermodynamic trap. If the concentration of the linear peptide in the reaction vessel is even marginally too high, the molecules collide. Instead of an intramolecular bond (closing the ring on itself), you get an intermolecular bond (two peptides fusing together). You create massive parallel dimers and polymeric aggregates. Yield plummets. The resulting dimers possess completely unpredictable receptor-binding affinities and are exceptionally difficult to purge via standard preparatory HPLC.
2. The β-Branched Blockade: Ile³ and Thr⁴
Look at positions 3 and 4: Isoleucine (Ile) and Threonine (Thr). Both of these are $\beta$-branched amino acids. When you attempt to couple two consecutive β-branched residues on a solid resin, they create a massive steric wall. The bulky side chains physically block the incoming activated amino acid from reaching the N-terminus. If the synthesis protocol relies on weak coupling reagents at room temperature, the reaction stalls. You end up with "-Ile" or "-Thr" deletion sequences. These deletions possess identical charge profiles to the target molecule and become nearly impossible to separate downstream.
3. The Asparagine (Asn) Dehydration Time-Bomb
Position 5 utilizes Asparagine (Asn). During SPPS, if the amide side chain of Asn is left unprotected and is exposed to strong activating reagents (like DIC), it rapidly undergoes a catastrophic dehydration reaction, converting the amide into a cyano (nitrile) group. This forms a permanent, highly toxic cyano-impurity. Even worse, if the Asn is protected, but the cleavage cocktail is not perfectly balanced, Asn can cyclize into a succinimide intermediate. A generic manufacturer ships you a batch that looks pure on a crude UV-HPLC scan, but the mass spectrometer reveals a cocktail of cyano and succinimide degradation products. It fails. Why? Because the manufacturer lacked the kinetics control during coupling and cleavage.
The Shaanxi Sunrise Architecture: Forging the Obstetric Baseline
At Shaanxi Sunrise (Pharma-Sunrise), we do not rely on standard industry shortcuts. We rely on brutally rigorous, data-driven chemical engineering. Our proprietary approach to Atosiban Acetate (CAS 90779-69-4) manufacturing is explicitly designed to dismantle the steric, stereochemical, and oxidation roadblocks that plague the sector.
To conquer the consecutive β-branched steric hindrance of Ile-Thr, our process engineering team utilizes highly reactive uronium-based coupling reagents (like COMU or HATU) combined with optimized microwave-assisted thermal cycling. To prevent Asn dehydration, we strictly utilize Trt-protected Asparagine derivatives and carefully titrate our activation chemistry. For the critical macrocyclization trap, we execute highly advanced, ultra-high-dilution liquid-phase oxidation protocols. We control the oxidative potential meticulously, kinetically favoring the intramolecular Mpa1-Cys6 ring closure and suppressing dimer formation to undetectable levels. Furthermore, our post-cleavage purification isn't a simple single-pass afterthought. We deploy multi-dimensional orthogonal Ultra-Performance Liquid Chromatography (UPLC) systems—utilizing incredibly shallow gradient slopes—to systematically isolate the pure Atosiban peak from closely eluting deletion or cyano impurities. We don't guess the purity. We map it with absolute precision.
Auditor's Metric: Generic Market Standard vs. Sunrise Parameters
The generic market grade settles for 98% purity. That leaves a massive 2% margin for unknown, potentially agonistic peptide fragments, dimeric aggregates, and cyano impurities. In an obstetric IV environment, a 2% impurity profile is a catastrophic liability. Below is the unvarnished analytical data comparison that dictates our uncompromising internal release criteria.
| Analytical Parameter | Generic Market Standard | Sunrise Internal Standard |
|---|---|---|
| HPLC Purity (Area %) | ≥ 98.0% | ≥ 99.50% (Strictly Enforced) |
| Single Maximum Impurity | ≤ 1.0% | ≤ 0.10% (Identified via HRMS) |
| Dimer Content (SEC) | Often > 0.5% | ≤ 0.10% (Kinetically suppressed) |
| TFA (Trifluoroacetic Acid) Limit | > 5.0% (Poor Exchange) | ≤ 0.5% (Strict Acetate Form) |
| Endotoxin Level (LAL Assay) | < 10> | < 1> |
| Peptide Content (N%) | > 80.0% | ≥ 85.0% (Elemental N-Analysis) |
The Final Mile: The Critical TFA-to-Acetate Ion Exchange
Even if the synthesis, cyclization, and purification processes are utterly flawless, the final isolation phase ruins countless commercial batches. Peptides are typically purified in mobile phases containing Trifluoroacetic acid (TFA). The resulting molecule is naturally a TFA salt. In an intravenous obstetric setting, infusing high levels of residual TFA directly into a pregnant patient's bloodstream is violently toxic. It triggers acute blood pressure spikes and cellular toxicity. It is entirely unacceptable for IV formulation.
At Shaanxi Sunrise, we execute highly specialized, large-scale ion-exchange chromatography protocols specifically designed for Atosiban. We strip the target molecule of the harsh TFA counter-ions and seamlessly convert it into a vastly more biocompatible Acetate salt, successfully driving residual TFA levels strictly below 0.5%. Following this rigorous exchange, our deep-freeze lyophilization cycle is exceptionally extended. We pull the vacuum down slowly, sublimating the solvent at precise thermodynamic ramps to ensure a highly porous, instantaneously soluble crystalline powder. Moisture content is locked strictly below 5.0%. No clumping. No degradation over time. Absolute, verifiable clinical stability.
Formulation & QA Auditor FAQ (Deep Dive)
Q1: How do you mathematically guarantee the absence of intermolecular dimers?
We do not rely on basic UV absorbance. Dimers elute very close to the monomer peak. Every single batch of Sunrise Atosiban Acetate API undergoes comprehensive High-Resolution Mass Spectrometry (HRMS) combined with Size-Exclusion Chromatography (SEC). We confirm the exact monoisotopic mass of the monomer (993.4Da). If the mass spectra detect any signal at ≈1986Da (the dimer), the batch fails release. We guarantee dimer limits well below 0.1%.
Q2: What is the exact endotoxin limit for your Atosiban powder?
Because Atosiban is primarily formulated for intravenous (IV) injection in critical care obstetrics, bioburden control is paramount. We enforce strict cleanroom protocols, utilize depyrogenated glassware, and execute terminal sterile filtration (0.22 μm) prior to the lyophilization step. Endotoxin levels are routinely tested via the kinetic chromogenic LAL assay. We strictly enforce a limit of
Q3: How do you verify that the D-Tyr(Et) residue hasn't racemized during synthesis?
Racemization of unnatural residues is a massive blind spot for generic factories. Standard C18 HPLC columns often cannot resolve D/L diastereomers. We utilize specialized chiral stationary phases during our in-process analytical checks. By applying highly tailored mobile phase gradients, we can force the separation of any L-Tyr(Et) impurities. Our chemists optimize the coupling reagents (e.g., using DIC/Oxyma instead of highly basic HATU/DIEA mixtures) to kinetically suppress the racemization pathway from the start.
Q4: Can you provide proof of the TFA to Acetate conversion?
Absolutely. We do not just make a theoretical claim. Every Certificate of Analysis (COA) for our Atosiban Acetate API includes a dedicated Ion Chromatography (IC) test result. We physically quantify both the Acetate content (to confirm the salt form) and the residual Trifluoroacetate (TFA) content. The TFA is strictly guaranteed to be ≤ 0.5%, ensuring absolute safety for your IV toxicology profiles.
Q5: How do you prevent the formation of cyano impurities at Asn5?
This is a critical failure point for amateurs. To prevent the amide side-chain of Asparagine from dehydrating into a nitrile (cyano) group during coupling, we strictly utilize Fmoc-Asn(Trt)-OH. The massive Trityl (Trt) protecting group acts as a steric shield, completely preventing the dehydration side-reaction. The Trt group is then safely removed during the final, carefully modulated global cleavage step, yielding pure Atosiban without cyano contamination.
Q6: Do you provide long-term ICH stability data for this API?
Yes. We recognize that robust stability profiling is non-negotiable for IND filings and commercial IV formulation studies. Shaanxi Sunrise conducts rigorous, ICH-aligned stability testing on multiple validation batches of Atosiban Acetate API. We subject the lyophilized powder to both long-term (e.g., 2-8°C) and accelerated degradation conditions to map out potential cyclization rupture or hydrolytic pathways over time. Comprehensive stability reports can be integrated into your technical data package upon request.
Do Not Compromise Your IV Pipeline with Substandard Peptides.
Shaanxi Sunrise (Pharma-Sunrise) provides verifiable, high-throughput Atosiban Acetate API (CAS 90779-69-4) engineered for the most rigorous global obstetric CDMOs. Demand the analytical data. We have it ready.
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