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Macrogol 15 Hydroxystearate Excipient | Uses, Suppliers, and Specifications

Macrogol 15 hydroxystearate is a mixture of mainly monoesters and diesters of 12-hydroxystearic acid and macrogols obtained by the ethoxylation of 12-hydroxystearic acid. The number of moles of ethylene oxide reacted per mole of 12- hvdroxystearic acid is 15 (nominal value). It contains about 30% free macrogols. It occurs a yellowish-white, almost odourless waxy mass or paste at room temperature, which becomes liquid at approximately 30oC.

Typical Physicochemical Properties

Acidity/alkalinity pH= 6-7 (10% w/v aqueous solution at 200C)
Critical micelle concentration 0.005-0.02%
Density 1.03g/cm3
Flash point 2720C
HLB value 14-16
Ignition temperature 3600C
Solidification temperature 25 – 300C
Solubility Soluble in organic solvents such as ethanol (95%), propan.2-ol, and very soluble in water to form clear solutions. Solubility in water decreases with Increasing temperature. Ii is insoluble in liquid paraffin
Viscosity (dynamic) 12 mPa s for a 30% w/v aqueous solution at 25o C 73mPas for a 30% w/v aqueous solution at 60oC

Applications in Pharmaceutical Formulation

Macrogol 15 hvdroxystearate is a dissolution rate enhancer; nonionic surfactant; solubilizing agent; stabilizing agent. It is used in preclinical testing of drugs, mainly for IV and other parenteral applications. The solubilizing capacity for some of the drugs evaluated (clotrimazole, carbamazepine, I7β-estradiol, sulfathiazole, and piroxicam) increases almost linearly with increasing concentration of macrogol 15 hvdroxystearate. This is due to the formation of spherical micelles even at high concentrations of macrogol 15 hydroxystearate.

Macrogol 15 hydroxystearare has been used in the manufacture of aqueous parenteral preparations with vitamin A, D, E and K, and a number of other lipophilic pharmaceutical active agents, such as miconazole. It is very efficient at solubilizing substances like fat-soluble vitamins and active ingredients that are hydrophobic in nature. It is also an excellent solubilizer for parenteral use, at a concentration of 20%, and the water solubility of different drugs may be enhanced by a factor of 10 – 100, depending on the structure of the drug molecule.
Pharmacopeia Specifications


Test Specification Reference
Identification + USP-NF/PhEur
Characters + USP-NF/PhEur
Acid value ≤1.0 USP-NF/PhEur
Appearance of solution + USP-NF/PhEur
Hydroxyl value 90 – 110 USP-NF/PhEur
Iodine value ≤2.0 USP-NF/PhEur
Peroxide value ≤5.0% USP-NF/PhEur
Saponification value 53 – 63 USP-NF/PhEur
Free macrogols 27.0 – 39.0% USP-NF/PhEur
Ethylene oxide ≤1ppm USP-NF/PhEur
Dioxane ≤50ppm USP-NF/PhEur
Nickel 1ppm USP-NF/PhEur
Water ≤1% USP-NF/PhEur
Total ash ≤0.3% USP-NF/PhEur

Safety and Regulatory Status

Macrogol 15 hydroxystearaic is used in parenteral pharmaceutical preparations in concentrations up to 50% to solubilize diclolenac, propanidid, and vitamin K1. It has also been used in preclinical formulations in preparing supersaturated injectable formulations of water-insoluble molecules. It is generally regarded as a relatively nontoxic and nonirritant excipient.

Macrogol 15 hydroxystearate is reported not to be mutagenic in bacteria, mammalian cell cultures and mammals.

LD50 (dog, IV): > 3.10 g/kg

LD50 (mouse, IP): >0.0085g/kg

LD50 (mouse, IV): >3.16g/kg

LD50 (rat, oral): >20g/kg

LD50 (rat, IV): 1.0-1.47g/kg

Stability and Storage Conditions

Macrogol 15 hydroxystearate has a high chemical stability. The prolonged action of heat may induce physical separation into a liquid and a solid phase after cooling, which can be reversed by subsequent homogenization. Macrogol 15 hydroxysrearate is stable for at least 24 months if stored in unopened airtight containers at room temperature maximum 250C). Aqueous solutions of macrogol 15 hydroxystearate can be heat-sterilized (121 oC/0.21 MPa). The pH may drop slightly during heating, which should be taken into account. Separation into phases may also occur, but agitating the hot solution can reverse this. Aqueous solutions can be stabilized with the standard preservatives used in pharmaceuticals.

Macrogol 15 hydroxysrearate should be stored in tightly sealed containers in a dry place.


Handling Precautions

Observe normal precautions appropriate to the circumstances and quantity of material handled.


[1] H. Bley, B. Fussnegger, R. Bodmeier, Characterization and stability of solid dispersions based on PEG/polymer blends, international journal of pharmaceutics, 390 (2010) 165-173.

[2] M.H. Aburahma, S.M. Badr-Eldin, Compritol 888 ATO: a multifunctional lipid excipient in drug delivery systems and nanopharmaceuticals, Expert opinion on drug delivery, 11 (2014) 1865-1883.

[3] P.J.C. Sheskey, Walter G; Cable, Colin G, Handbook of Pharmaceutical Excipients – 8th Edition, Pharmaceutical Development and Technology, 18 (2017) 544-544.

[4] K. Viaud-Quentric, S. Lefranc-Jullien, L. Feraille, P.P. Elena, Long-term tolerance of preservative-free eye drops containing macrogol hydroxystearate as an excipient, journal francais d ophtalmologie, 39 (2016) 156-163.

[5] A.V. Gore, K.S. Warner, C.P. Pujara, R.S. Graham, A.P. Parashar, M.-L. Lee, R.S. Jordan, S. Likitlersuang, MACROGOL 15 HYDROXYSTEARATE FORMULATIONS, 2012.

[6] J. Rossi, C. Allen, R. D’Souza, J.-C. Leroux, Oil-in-water emulsions, methods of use thereof, methods of preparation thereof and kits thereof, 2007.



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