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Polyoxyethylene 35 Castor Oil Elp BP EP USP Pharma Grade stands out as a nonionic surfactant derived by reacting ethylene oxide with castor oil. Drug manufacturers recognize this product for its unique capacity to dissolve both hydrophobic and hydrophilic compounds, supporting a wide spectrum of pharmaceutical applications. Unlike other emulsifiers that break down or become unstable under intensive processing, this grade of polyoxyethylene castor oil maintains its integrity across a wide pH range and in hot or cold environments. Its multipurpose versatility traces back to the modification process, where castor oil’s triglycerides meet a high number of polyoxyethylene units, producing a molecular structure with an optimal balance between hydrophilic and lipophilic segments. This balance proves essential for forming stable emulsions in injections, oral solutions, and topical ointments.
The physical structure of Polyoxyethylene 35 Castor Oil Elp comes from a reaction yielding a mixture largely composed of ethoxylated fatty acid esters. In its pharma-grade form, it typically presents as a pale yellow, viscous liquid, though in colder climates, it may thicken but never solidifies fully like raw castor oil or pure PEG polymers. Batches rarely exhibit any odor, and where a smell is discerned, it remains faintly reminiscent of vegetable oils. The substance dissolves swiftly in water, and compatibility extends to ethanol, propylene glycol, and many polar solvents often used in drug formulations. Specific gravity hovers around 1.06 to 1.10 g/cm³ at room temperature, reflecting its substantial molecular weight—usually between 2,500 and 3,500 Daltons, confirmed by batch-specific analysis. Defining the property further, it resists crystallization thanks to the repeating ethylene oxide arms, which also render the solution optically clear when mixed with water.
Chemically, Polyoxyethylene 35 Castor Oil features a backbone consisting of the triglyceride portion from castor oil, where approximately 35 moles of ethylene oxide react with each molecule. The general molecular formula takes the form C57H104O21(C2H4O)n, with “n” representing the number of –CH2CH2O– units added. This structure imparts a sizable hydrophilic-lipophilic balance (HLB), making it indispensable for solubilizing poorly soluble drugs. Under microscopic inspection, the solution remains uniform, free of visible crystals, flakes, or sediment, ensuring that high-purity pharmaceuticals experience no dosage variability due to ingredient settling.
Pharma-grade Polyoxyethylene 35 Castor Oil adheres to recognized standards, including BP, EP, and USP monographs. These standards guarantee active substance content, purity level, and elimination of potential contaminants such as free ethylene oxide or diethylene glycol. Typical tests confirm refractive index between 1.450 and 1.460 at 20°C, and an acid value less than 2 mg KOH/g. Relative density sits tightly controlled, and water content rarely exceeds 1.5% by weight. Many suppliers document the HS Code as 34021300—critical for regulatory, trade, and customs tracking for importation and exportation into global markets. The product arrives mostly as a viscous, clear-to-hazy liquid, though concentrated grades may display a thicker consistency. Solubility in water ensures removal of the guesswork in production lines, while solutions remain transparent throughout shelf life when stored sealed at room temperature.
The industry almost exclusively favors liquid form due to ease of mixing, metering, and dispensing. By contrast, alternative physical forms—such as solid, powder, pearls, flakes, or crystals—rarely meet pharma-grade expectations, mostly due to handling, uniformity, and consistency issues at scale. In its correct handling state, the liquid pours sluggishly, akin to castor oil, yet blends instantly with other liquid excipients. No significant reports of product arriving as flakes or granules exist in pharmaceutical supply chains. Storage at low temperatures sometimes increases viscosity, but no freezing occurs unless subject to deep refrigeration. Color inspections show no significant deviation, as notable color shifts may suggest contamination or degradation by light.
Polyoxyethylene 35 Castor Oil, meeting BP, EP, USP specifications, carries a well-documented safety record across decades in injectable, oral, and topical drug delivery. Exhaustive studies support its inclusion in medications given to vulnerable groups, including neonates and oncology patients. Still, hypersensitivity remains a rare but discussed side effect with specific populations, particularly following repeated or high-dose administration. Rigorous controls lower the risk of residual ethylene oxide, a potent toxin, remaining in the raw material. Handling at the manufacturing level generally requires eye protection and gloves due to its tendency to dry hands or cause mild skin irritation with prolonged exposure. Material safety data sheets (MSDS) classify the product as harmful only under specific overdose ingestion or direct intravenous misuse rather than under routine handling. Regulatory authorities across North America, Europe, and Asia frequently audit suppliers and assign the HS Code for transparent logistics and shipment monitoring, ensuring compliance and traceability from raw castor oil acquisition through ethoxylation and purification.
Manufacturers rely on Polyoxyethylene 35 Castor Oil as a go-to raw material for solubilizing poorly water-soluble drugs, including ivermectin, cyclosporine, vitamin E, and specific chemotherapeutics. In these contexts, its performance outpaces simpler emulsifiers or surfactants that fail under physiological pH or in the presence of common stabilizers. The product achieves a rare balance between stability in solution and compatibility with a range of active pharmaceutical ingredients (APIs), preventing precipitation or cloudiness across changing temperatures on the shelf or in clinical settings. Formulators have learned through experience that switching to alternative surfactants often means sacrificing either solubility or safety. Extensive global experience supports the ingredient’s widespread adoption in both ready-mix preparations and compounding pharmacies, where certainty in final product clarity and stability reduces risk and waste.
My years following excipient safety highlight the need for relentless vigilance. Monitoring for trace ethylene oxide moved from recommended best practice to a regulatory mandate after past contamination incidents, which the industry responded to with advanced purification strategies and more rigorous batch testing. Reports of anaphylaxis, while vanishingly rare, necessitated better labeling and post-market surveillance, driving improvements in both product information and handling protocols at hospitals and pharmacies. Improved documentation—batch analyses, certificates of analysis (COAs), material safety data, and complete supply chain records—underpins confidence in each shipment’s quality. Producers continue optimizing synthesis to further reduce unwanted byproducts and environmental impacts of manufacturing, actively participating in global discussions about green chemistry and pharmaceutical sustainability.
The story of Polyoxyethylene 35 Castor Oil in pharmaceutical science is one of consistent evolution, driven by needs in drug solubility, safety, and regulatory rigor. The product’s standing as a stable, dependable raw material reflects decades of refinement in both chemistry and large-scale manufacturing. R&D teams, pharmacists, and regulatory officers see it not only as a functional material but as a benchmark for excipient safety and traceability. Ongoing research, industry openness about adverse events, and continual raising of quality standards mean future iterations of this ingredient will be safer and even better adapted for new drug challenges on the horizon.
Chengguan District, Lanzhou, Gansu, China
