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Polyoxyl 40 Stearate has roots that trace back to the golden age of pharmaceutical excipients in the early and mid-twentieth century, a period when the demand for stable emulsifying agents skyrocketed. Chemists explored ways to blend hydrophobic and hydrophilic properties for medicines that were becoming more complex. The solution arrived in the form of ethoxylated fatty acid esters, with Polyoxyl 40 Stearate carved out of that family. Today, British, European, and United States pharmacopeias acknowledge its significance, having outlined robust standards to guide its manufacture. This evolution has not just influenced industrial scale-up—it's taught many in the industry, myself included, how chemical ingenuity meets everyday medical needs.
Manufacturers produce Polyoxyl 40 Stearate by anchoring about forty moles of ethylene oxide onto each mole of stearic acid, yielding a nonionic surfactant recognized as PEG-40 Stearate. Whether in a chemistry classroom or a pharmaceutical compounding room, the focus rests on its role as a versatile excipient—critical for forming ointments, creams, and capsules that persist through shelf lives and changing storage conditions. The texture carries that waxy feel between the fingers, melting gently at body temperature, which always leaves a memorable impression during excipient demos.
Polyoxyl 40 Stearate lingers as a white to pale yellow waxy solid, easy to identify due to its unique silky slip and mild, fatty odor. Its hygroscopic nature stands out; over months in a humid storeroom, exposed surfaces can clump—reminding anyone handling it that proper storage matters. The substance dissolves easily in warm water and ethanol, forming clear solutions at the right concentrations, with a melting point usually between 48 and 53°C. Its high HLB (hydrophilic-lipophilic balance) means quick and stable emulsification, plenty of times observed during quick and successful emulsion tests on the bench.
Pharmacopeial specifications require careful monitoring of parameters: degree of ethoxylation, acid and saponification values, content of free polyethylene glycol, and limits on impurities. Bulk packaging for industry comes marked for batch number, net weight, country of origin, and dates that caution against mishandling. For those responsible for quality assurance, familiarity with the Certificate of Analysis and the technical dossier isn’t just paperwork—it's crucial for GMP compliance and product integrity.
The manufacturing process involves controlled reaction of stearic acid under alkaline conditions with ethylene oxide in a pressurized reactor. Skilled operators adjust temperatures and gas flow rates over several hours, guiding the process with years of hands-on experience that no standard operating procedure can fully capture. Post-reaction, neutralization, washing, and purification remove crude elements, leaving a polished excipient. Plant visits always provided perspective—the faint, soapy aroma in the air signals the precise synthesis in progress.
Polyoxyl 40 Stearate can undergo hydrolysis under acidic or basic conditions, breaking down to stearic acid and polyoxyethylene chains. In formulation research, this knowledge pressed for stability testing over entire development cycles. Chemists exploit its mild reactivity to bond with other ester compounds in unique delivery platforms, searching for ways to boost solubility, mask tastes, or slow drug release. Over time, these modifications drove the market to recognize Polyoxyl 40 Stearate as more than just another surfactant—it is a trusted tool in the formulator’s kit.
Common synonyms include PEG-40 Stearate, Polyoxyethylene(40) Stearate, and Macrogol Stearate 40, with various commercial labels influenced by manufacturer branding and local regulations. In libraries and procurement systems, I learned to search with a keen eye, as identical molecules often parade under different guises across countries and regulatory lists.
Cleaning up Polyoxyl 40 Stearate spills or inhaling its dust is rarely hazardous, but direct skin and eye contact need quick water rinses, as outlined in MSDS reports. The excipient’s long safety record gets confirmed by periodic toxicological reviews—animal and human data support its low irritancy and allergenic potential. Operators in manufacturing dress in standard protective gear, knowing that good hygiene is the best defense. Quality teams check every batch for microbial and heavy metal contaminants, aligning each shipment with Good Manufacturing Practices. Few people realize how much safety culture underpins every shipment and every spoonful dispensed in the lab.
In pharmaceuticals, Polyoxyl 40 Stearate partners with active compounds in creams, lotions, suppositories, and even some oral capsules. Its smooth melting profile means it delivers actives with minimal irritation—a feature I’ve watched patients appreciate especially in topical products. Nutraceutical and cosmetic brands lean into its emulsifying power for stable creams and hair products, learning over the years how only small tweaks in concentration can change product feel and performance. Its value doesn’t stop at drug delivery—food and veterinary industries also trust it, acknowledging the years of human safety data that support crossover uses.
Establishing Polyoxyl 40 Stearate’s utility was a collaborative feat—pharmacists, analytical chemists, and engineers teamed up to test improved blends and new grades. Research labs bench-test its performance with poorly soluble drugs or biologics, hunting for enhanced delivery systems. Academic literature now brims with studies assessing its molecular interactions, new applications with nanoparticles, and combination strategies for time-release tablets. Meeting regulatory authorities means presenting stacks of data—manufacturers have learned to document every nuance of performance, leading to stronger, safer formulations year by year.
Researchers assessed Polyoxyl 40 Stearate across multiple animal models and in vitro assays, looking for any evidence of irritation, sensitization, or toxic residue buildup. The compound clears the body rapidly, and high-dose animal tests underscore its low systemic toxicity—an important reassurance for clinicians and patients alike. Studies evaluated chronic exposure, genotoxicity, and reproductive impact, each time updating safety thresholds to match latest findings. Regulatory vigilance has kept standards high, and the track record helps built trust with prescribers and product developers. I remember the early cautionary tales—questions settled only by thorough evidence and steady oversight.
The future holds new roles for Polyoxyl 40 Stearate as personalized medicine and advanced drug delivery technologies push chemists to discover inventive uses. Interest in plant-based and biodegradable excipients grows, sparking questions about renewable sources for PEG chains or the environmental impact of ethoxylates. Green processing trends could usher in next-generation production, pairing sustainable sourcing with stricter ecological compliance. Research now targets ways to further reduce residual ethylene oxide and impurities, aiming for cleaner profiles without sacrificing performance. Watching these trends unfold, the lessons from Polyoxyl 40 Stearate’s long history anchor its promise—flexibility, safety, and adaptability will shape its place in tomorrow’s medicine cabinet.
Polyoxyl 40 stearate turns up in a lot of places you might not expect. In the world of pharmaceuticals, it handles jobs that other materials can’t always pull off. This ingredient comes from the reaction of stearic acid—a fatty acid sourced mainly from plants or animals—with polyoxyethylene. The resulting substance looks pretty unexciting. It comes in white to off-white flakes or powder and stays solid at room temperature.
The role of polyoxyl 40 stearate shines where it improves how tablets and ointments feel and behave. In my early work formulating topical medications, this additive behaved like a problem-solver. If a cream wouldn’t blend or a tablet stuck together, I would add a small amount of polyoxyl 40 stearate, and suddenly everything mixed the way it should. Manufacturers choose this material because it helps combine substances that usually fight to separate—water and oil, for example. Ointments rely on it so they spread easily and don’t feel greasy on the skin.
People don’t always consider what happens after swallowing a pill. A drug’s journey doesn’t get easier after it leaves the mouth. Polyoxyl 40 stearate steps in to make that journey smoother. Its surfactant properties help dissolve drugs that don’t play well with water. Medications, especially those treating chronic conditions, often contain substances that resist dissolving. Polyoxyl 40 stearate surrounds those stubborn particles, helping the body break them down and absorb them. This practical function means more reliable results for the patient and fewer complaints about medicine not working.
Polyoxyl 40 stearate that carries BP, EP, or USP credentials meets tough standards. These letters signal that a product meets specifications set by British, European, or United States Pharmacopeia organisations. Every batch must pass tests checking for purity, composition, and safety. In my experience, sticking to these grades protects companies from recalls and lawsuits. Pharmaceutical grade means every hospital and pharmacy can rely on what’s inside the package—no corners cut, no mystery substitute ingredients.
People might not get excited about what keeps tablets from sticking together, but anybody relying on those medicines should care. Adverse reactions can happen if inactive ingredients interact in the wrong way or contain contaminants, so sticking to high standards matters. Between 2017 and 2022, the Food and Drug Administration issued more than 150 recalls related to inactive ingredients. Many could have been prevented by using proper pharmaceutical-grade products. Polyoxyl 40 stearate sticks to those standards.
With rising concern over allergies and animal-derived ingredients, more companies now search for plant-based or synthetic alternatives. Polyoxyl 40 stearate can come from vegetable oils, which reduces the risk for allergic reactions tied to animal products. That shift helps create medicines friendly to a broader group.
Polyoxyl 40 stearate’s future rests in the hands of skilled chemists and quality control teams. Regulators must keep watching, but companies that invest in quality early avoid serious problems down the road. Paying attention to these details behind the scenes keeps medicines safer and more trustworthy for everyone who depends on them every day.
Drug formulations today involve a lot more than just active molecules. Every tablet, capsule, or cream gets a mix of helpers called excipients, each with its own job—some help with mixing, some stop pills from sticking, and some help active ingredients dissolve at the right speed. Polyoxyl 40 stearate is one of these helpers. It's a non-ionic surfactant, and that means it sits well in both watery and oily stuff, making it handy for medicines that need a bit of both. But safety always comes into play with anything that winds up in medicines, so let’s dig into the real-world side of things.
Regulators look hard at anything that goes into medicine, and polyoxyl 40 stearate didn't slide through unnoticed. Groups like the FDA and the European Medicines Agency set some strict requirements for excipients. They lean on studies that check not only for immediate side effects but also for what happens over the long haul. Toxicology research shows that polyoxyl 40 stearate, at the doses used in medicines, generally behaves as expected: it doesn't mess with your DNA or cause any scary growths in lab animals. Sky-high doses can bother the gut, but this holds true for nearly all surfactants, and medicines keep well below those numbers.
Every ingredient has a flip side, even those you see in your bathroom cabinet. There’s no getting around the fact that hypersensitivity pops up here and there—some people’s bodies just don’t like certain chemicals, even benign-seeming ones. Rare reports exist about contact dermatitis or mild rashes, but these stay low compared to ingredients like certain food dyes or peanuts. Folks with stearic acid allergies (which is rare) might need extra attention. Drugmakers already factor these rare cases into design, and clear labeling plus proper patient screening can cover most issues before they become problems.
I remember walking through a medicine factory, stacks of pill bottling lines humming away. Most people would be surprised by the sheer variety of binders, fillers, and lubricants that go into each batch. Not all drugs dissolve or mix easily, and the human gut isn’t as forgiving as a beaker in a science lab. Polyoxyl 40 stearate helps with tough molecules that won’t dissolve in water alone. Some antifungals, antivirals, and even vitamins absorb much better with a boost from compounds like this one, which means doctors can prescribe lower doses and still get results.
I’ve talked to pharmacists and seen the concern people have about "chemical-sounding" names on medicine labels. It’s fair to ask—sometimes companies haven’t done a good job explaining what these ingredients do. Good science depends on transparency, and it’s on both regulatory agencies and drugmakers to keep the facts out in the open. The track record with polyoxyl 40 stearate shows a strong safety margin when used as intended. Side effects rarely pop up, and those that do tend to be mild, resolving quickly after stopping the medication.
The real test comes as more complex drugs appear. Each new medicine gets a fresh review, no matter how routine the ingredients seem. If new studies reveal problems, there are safer alternatives ready—no company wants lawsuits, and no regulator wants public health risks on their watch. Pushing for continual safety checks, post-market surveillance, and making adverse event data easy for patients and providers to find would keep trust strong. Patients benefit most when they know not just that something works, but that it’s built on solid, ongoing evidence.
Polyoxyl 40 stearate is one piece of a much bigger puzzle. The story here is about more than one surfactant—it’s about science, regulation, and public trust working together. If regulators and the industry stick with rigorous safety standards and open communication, patients can count on the next pill they take being safe—right down to the ingredients most people never notice.
Polyoxyl 40 Stearate, sometimes called PEG-40 Stearate, shows up a lot in tablets and creams, but many people skip past its purpose. As a non-ionic surfactant and emulsifier, it connects oil and water—two things that typically want nothing to do with each other. If you’ve ever wondered how lotions stay smooth or how a drug releases evenly in your body, there’s a decent chance Polyoxyl 40 Stearate plays a role. In pharmaceutical use, British Pharmacopoeia (BP), European Pharmacopoeia (EP), and United States Pharmacopeia (USP) each give this ingredient clear benchmarks to protect safety and quality.
This ingredient generally comes as a cream-colored to light yellow substance, waxy to the touch. In my experience with pharmacy compounding, a small difference in color or feel can give a hint about purity differences—an off-smell or gritty texture usually means you’re facing quality issues. Real Polyoxyl 40 Stearate from a reputable source smells mild, nothing sharp or chemical.
The design of this molecule bridges polyethylene glycol (PEG) and stearic acid. That molecular backbone gives it an HLB (hydrophilic-lipophilic balance) value that sits between 15 and 17. That just means it loves water, but still connects with oils. If you tried dissolving it, you’d see it melts easily in hot water and alcohols.
Pharmacopoeial grades set serious rules about what counts as "pharma grade". Most global APIs or excipients like Polyoxyl 40 Stearate must hit these numbers:
You may think specs are boring. In practice, any slip can bring headaches—think ruined medicine batches, unexpected patient reactions, or recalls. I’ve handled raw material batches flagged for impurities, and it’s always the specs that tip us off. One tainted drum can shut down a production line, put patients at risk, or spark a regulatory inspection.
Polyoxyl 40 Stearate means safety for topical and oral drugs. Every specification—whether it’s about melting, residues, or metals—protects against contamination. These checks guarantee the emulsifier doesn’t release unexpected substances, and they support stable dosage forms. For instance, coatings on a tablet or the base of a cream rely on the right balance of hydrophilic and lipophilic character to deliver active ingredients accurately.
Pharmaceuticals have come a long way on ingredient quality, but oversights still happen. More transparency in sourcing and frequent independent testing would catch outliers early. Sustainable sourcing could help too; stearic acid often comes from palm oil, and demand for sustainable supply chains with traceability is growing in both healthcare and food. Simple batch tracking—letting customers see certificates and audits—builds trust on both sides. And a strong relationship between the science bench and supply chain teams closes gaps before issues reach patients.
In the end, Polyoxyl 40 Stearate is one piece of a much bigger picture: keeping medicines safe and working as promised, every time.
Polyoxyl 40 Stearate tends to show up on ingredients lists in pharmaceuticals and cosmetics, helping creams stay creamy and tablets hold together. Many people who manage inventory see only the name and not the risks. I’ve noticed, through years in a compounding pharmacy, that it’s easy to take excipients for granted. After all, it’s not the active drug, right? But a little negligence with this kind of compound can ruin products or lead to safety problems for staff.
Think of Polyoxyl 40 Stearate like butter, not baking soda. It’s a waxy, soft solid and doesn’t keep well in heat or humidity. Once, a colleague stored it in the top drawer near a sunny window. By the end of the week, the stuff turned tacky and weirdly colored—a whole batch wasted because it left a residue that wouldn’t blend out. That’s lost money and effort straight into the trash.
This excipient prefers a room that stays cool and dry, away from sunlight. Manufacturers usually recommend storage below 25°C (77°F), away from direct sources of heat. Even one day of higher temperatures may change its texture, affecting how it functions in a finished product. You risk not only ruined texture, but also lower product quality—something folks in the pharmaceutical world can’t afford.
Handling starts with respect for the health of the staff working the benches and packing the drums. Polyoxyl 40 Stearate may sound gentle, but its dust can irritate eyes, nose, and throat. Personal experience taught me that simple habits go a long way—wearing gloves, a dust mask, and goggles keeps accidental sneezes and coughs out of the working day. It’s wise to work in a ventilated area and to keep containers closed right after scooping what you need. I’ve seen too many people waste time cleaning up powder spills—they cake into tiles and, worse, travel onto other equipment.
The container makes a difference. Once I met a distributor who switched from tight-sealed buckets to plastic bags to save money. The result? Moisture crept in, clumping the powder and growing a faint musty smell. That entire shipment had to be discarded because no one wanted to risk contamination.
Polyoxyl 40 Stearate spills linger as slippery patches that no mop seems to catch. Staff should treat spills seriously, cleaning them with a damp cloth rather than sweeping which can kick particles into the air. Old instructions sitting in a binder collect dust as fast as the compound itself, so regular reviews and staff refresher sessions help.
Inventory rotation matters, too. I’ve seen old batches left for years, and the stearate at the bottom goes yellow or cakes up. That’s not just unsightly, it’s risky—expired excipients can carry unknown consequences for patients or customers. Good records and dated labels help avoid that pitfall.
Strong policies, proper equipment, and a bit of practical wisdom keep Polyoxyl 40 Stearate in top shape from delivery to final dosage. Taking shortcuts or ignoring changes in appearance or smell usually backfires, and the stakes can be people’s health or big financial loss. A reliable process built on good science and a dash of respect for practical experience protects everyone.
Pharmacists and formulators see Polyoxyl 40 Stearate show up a lot in projects. This surfactant, made by sticking polyethylene glycol onto stearic acid, takes the spotlight in tablets, ointments, and even some injectable drugs. My early years in pharmaceutical compounding taught me that no single ingredient works as a magic bullet—each plays off the others, sometimes like teammates and other times like rivals. So, Polyoxyl 40 Stearate, though famous for smoothing out emulsions and boosting solubility, always pushes us to check how it mixes with other helpers in the recipe.
Direct compression blends rely on the reliability of their fillers and binders. Polyoxyl 40 Stearate rarely stirs up trouble with common choices like microcrystalline cellulose or lactose. I remember being surprised by how well it blended in—there’s no awkward stickiness or separation, provided the batch stays at room temperature. In some high-load formulas, it can soften up harder binders, but rarely enough to ruin the mechanical strength of your tablets. Research backs up these observations, with stability studies in tablet blends showing no weird degradation products when these excipients sit together for months on the shelf.
Mixing Polyoxyl 40 Stearate into a formula with strongly alkaline ingredients does send up some red flags. In a compounding session, I mixed it with magnesium oxide and the result wasn’t pretty. Some excipients, like magnesium stearate, carry their own PEG tails, and those can sometimes act like oil and water with Polyoxyl 40 Stearate—too much overlap causes caking or slows drug dissolution. Also, it’s worth checking for any unexpected taste or odor changes in chewable tablets.
The stearate part loves fatty environments, but the PEG tail pulls in moisture. That conflict means storing drugs with Polyoxyl 40 Stearate next to hygroscopic excipients like mannitol or sorbitol can sometimes lead to clumping in the blend. This happened in my own practice: a batch meant to be smooth for direct compression started to clump because the warehouse faced a humid summer spell. Too much water pulled in from the air invited microbial growth, pushing us to toss the batch. Getting the storage right fixes most of those struggles, but skipping the stability checks can invite nasty surprises.
Researchers have tried to unravel these little mysteries with stability studies and real-world compounding rounds. The US Pharmacopeia and pharma handbooks remind us to check for peroxide formation or PEG degradation, especially in formulas rich in oxidizing agents. Careful pre-formulation screening, in my experience, helps spot trouble before it grows. Simple blend studies in the lab—watching appearance, capturing moisture by Karl Fischer titration—go a long way. This process keeps medication safe, cuts waste, and helps teams sleep easier.
People working with polyoxyl 40 stearate get better results by partnering it with neutral excipients, steering clear of strong bases or reactive oxidants. High-shear mixing sometimes improves distribution, but overstressing the blend in the name of speed can backfire. Batch records, material compatibility charts, and storage temperature logs all seem like annoying paperwork—until you run into a failed batch or recall. Relying on sound facts, smart lab work, and a bit of hands-on caution goes further in answering the compatibility question than any one text or supplier’s data sheet alone.
| Names | |
| Preferred IUPAC name | Polyoxyethylene (40) stearate |
| Other names |
PEG-40 Stearate Polyethylene Glycol 40 Stearate Macrogol 40 Stearate Polyoxyethylene Stearate Polyoxyethylene (40) Stearate Myrj 52 |
| Pronunciation | /ˌpɒl.iˈɒk.sɪl ˈfɔːr.ti ˈstɪə.reɪt/ |
| Identifiers | |
| CAS Number | [9004-99-3] |
| 3D model (JSmol) | `3D structure; JSmol; C76H152O8` |
| Beilstein Reference | Beilstein Reference 4-179-05 |
| ChEBI | CHEBI:53419 |
| ChEMBL | CHEMBL1208371 |
| ChemSpider | 184700 |
| DrugBank | DB11107 |
| ECHA InfoCard | 13e47abc-4c8e-4f4a-9e0a-d2d851763e60 |
| EC Number | 9004-99-3 |
| Gmelin Reference | 7819 |
| KEGG | C16117 |
| MeSH | D015359 |
| PubChem CID | 24894112 |
| RTECS number | WL3450000 |
| UNII | 5Y35372186 |
| UN number | UN3082 |
| CompTox Dashboard (EPA) | DTXSID5047020 |
| Properties | |
| Chemical formula | C76H152O8 |
| Molar mass | ~2,700 g/mol |
| Appearance | White or almost white, waxy, hydrophilic flakes or granules |
| Odor | Odorless |
| Density | 0.96 g/cm³ |
| Solubility in water | Dispersible in water |
| log P | 1.6 |
| Vapor pressure | Negligible |
| Acidity (pKa) | Acidity (pKa): "4.5 |
| Basicity (pKb) | 7.5 |
| Refractive index (nD) | 1.453 |
| Viscosity | 30 to 55 mPa.s (measured as a 5% w/w aqueous solution at 25°C) |
| Dipole moment | 1.61 D |
| Pharmacology | |
| ATC code | A06AG02 |
| Hazards | |
| Main hazards | May cause eye, skin, and respiratory irritation. |
| GHS labelling | **"Not a hazardous substance or mixture according to Regulation (EC) No 1272/2008 (CLP/GHS)"** |
| Pictograms | GHS07,GHS08 |
| Signal word | Warning |
| Hazard statements | No hazard statements. |
| Precautionary statements | Keep container tightly closed. Store in a cool, dry place. Avoid contact with eyes, skin, and clothing. Wash thoroughly after handling. Avoid inhalation of dust or vapors. Use only with adequate ventilation. |
| NFPA 704 (fire diamond) | NFPA 704: 1-1-0 |
| Flash point | > 220°C |
| Autoignition temperature | > 350°C |
| Lethal dose or concentration | LD50 (Rat, oral): >25 g/kg |
| LD50 (median dose) | > > > > > > > "LD50 (oral, rat): > 25 g/kg |
| NIOSH | TRN9483800 |
| REL (Recommended) | Not more than 25 mg/kg body weight |
| Related compounds | |
| Related compounds |
Polyoxyl 10 Stearate Polyoxyl 20 Stearate Polyoxyl 60 Stearate Polyoxyl 100 Stearate PEG Stearate Polysorbate 60 Polysorbate 80 |
Chengguan District, Lanzhou, Gansu, China
