Overview[1-2]
Polyethylene glycol is a polymer of ethylene oxide hydrolyzate. It is non-toxic and non-irritating and is widely used in various pharmaceutical preparations. All grades of polyethylene glycol are soluble in water. Polyethylene glycols can be mixed with each other and with water in any proportion. High molecular weight polyethylene glycol aqueous solutions can form gels. This product has a certain stabilizing effect on some drugs that are easily hydrolyzed. Polyethylene glycol 1000 is a representative Newtonian fluid pharmaceutical excipient. The 34th edition of the United States Pharmacopoeia (USP34), the 2011 edition of the British Pharmacopoeia (BP2011) and the 2010 edition of the Chinese Pharmacopoeia (ChP2010) all use a capillary viscometer to measure its kinematic viscosity. , but the capillary used in commonly used antioxidant viscometer specifications, the mass concentration of the sample solution, and the measurement temperature are quite different.
Purpose[1]
Polyethylene glycol is widely used in a variety of pharmaceutical preparations, such as injections, topical preparations, ophthalmic preparations, oral and rectal preparations. Solid grade polyethylene glycol can be added to liquid polyethylene glycol to adjust the viscosity for topical ointments; polyethylene glycol mixtures can be used as suppository bases; aqueous polyethylene glycol solutions can be used as suspending agents or to adjust other The viscosity of the suspension medium; the combination of polyethylene glycol and other emulsifiers can increase the stability of the emulsion. In addition, polyethylene glycol is also used as a film coating agent, tablet lubricant, controlled release material, etc.
Stability and storage conditions[1]
Polyethylene glycol is chemically stable in the air and in solution, but polyethylene glycol with a molecular weight lower than 2000 is easily hygroscopic. Polyethylene glycol is not suitable for microbial growth and is not prone to rancidity. Polyethylene glycol and polyethylene glycol aqueous solutions can be sterilized by autoclaving, filtration sterilization or gamma ray sterilization. If solid polyethylene glycol is sterilized by dry heat at 150°C for 1 hour, it can induce oxidation and cause degradation. Polyethylene glycol should be stored in a cool, dry place and in an airtight container. Liquid grade polyethylene glycol can be stored in stainless steel, aluminum, or glass containers.
Incompatibility[1]
Liquid and solid levels of polyethylene glycol are incompatible with certain pigments; polyethylene glycol can reduce the activity of antibiotics, especially penicillin and bacitracin; hydroxyphenyl ester preservatives can be affected by the activity of polyethylene glycol. Complexing with American Albemarle weakens the antiseptic effect; phenol, tannic acid, and salicylic acid can soften and liquefy polyethylene glycol; sulfonamides and dithranol can change color due to their effects; and compatibility with sorbitol can produce precipitation. .
Viscosity measurement[2]
1) Preparation of solution: Precisely weigh 250g of PEG1000, a total of 2 portions, put each into 500ml and 250ml measuring bottles, add water to dissolve and dilute to volume, and prepare solutions with concentrations of about 33% and 50%.
2) Determination of the kinematic viscosity of the solution using Ping’s capillary viscometers with inner diameters of 0.8, 1.2 and 1.5mm, respectively, to measure the kinematic viscosity of PEG1000 solutions with concentrations of 33% and 50% at 20°C. The results are shown in the table.
This method is simple, accurate and reproducible.
Main reference materials
[1] Source: New Practical Manual of Veterinary Drugs
[2] Research and verification of polyethylene glycol 1000 viscosity determination method
