PEG in Pharmaceutical Preparations (I): Solvents, Lubricants, Adhesives and More

Polyethylene glycol (PEG) is polymerized from ethylene oxide and monoethylene glycol (or diethylene glycol) under the catalysis of an alkaline catalyst. The molecular weight varies depending on the degree of polymerization, usually around 200~35,000. The properties of PEG vary with molecular weight. Currently, common PEG types include PEG 200, PEG 300, PEG 400, PEG 600, PEG 2000, PEG 4000, PEG 6000, PEG 8000, etc.

Our PEG for Pharmaceutical Preparations

BOC Sciences is a leading supplier of PEG products and services, offering a broad range of high-quality PEG raw materials and PEGylation technology to support drug preparation development and manufacturing processes. We offer a full range of PEG products, including PEG polymers, PEG derivatives and PEG conjugates, to meet the diverse needs of pharmaceutical researchers and manufacturers. Our PEG raw materials include:

PEGs for Pharmaceutical Solvents

PEG 200, PEG 300, PEG 400, and PEG 600 are colorless, slightly odorous viscous liquids with stable chemical properties, safety and low toxicity, so they are often used as solvents for drugs. In addition, in order to increase the solubility of poorly soluble drugs, latent solvents, namely mixed solvents composed of ethanol, glycerol, propylene glycol, benzyl alcohol, polyethylene glycol, etc. and water, are often used.

PEGs for Soft Capsules

The capsule materials of soft capsules are mostly composed of a certain proportion of gelatin, plasticizer and water, so drugs and additives that have no effect on protein properties can be filled. Such as various oils, liquid drugs, drug solutions, drug suspensions and solid drugs, etc. Since low molecular weight PEG is miscible with water, it is a good solvent for water-soluble drugs and certain organic drugs, such as nifedipine soft capsules. At present, soft capsules are mostly made of solid drug powder suspended in an oily or non-oily (PEG 400, etc.) dispersion medium. It has also been reported that the use of polyethylene glycol as a solvent for chloral hydrate can greatly reduce its decomposition of gelatin protein.

PEGs for Injections

Since PEG 200 to PEG 600 can improve the solubility of poorly soluble drugs and stabilize water-labile drugs, they can be used as injection solvents. Injections that only use PEG as the injection solvent are rare. For example, thiotepa injection uses PEG 400 or PEG 600 as the solvent, which can avoid the aggregation and sedimentation of thiotepa in water. However, mixed solvents (latent solvents) are generally used. For example, when V(PEG 300):V(benzyl alcohol):V(propylene glycol)=80:5:15, it can be used as a mixed solvent for 5% progesterone or testosterone injection. After these two injections are injected intramuscularly, they will precipitate locally when in contact with body fluids, forming a drug warehouse, which is gradually released from the tissue and has a long-lasting effect.

PEGs for Eye Drops

Studies have shown that indomethacin eye drops can be made using PEG 400 as a solvent. The results of a stability study conducted on this eye drop showed that the PEG 400 formulation was superior to the Span80 formulation. In addition, PEG can be used as a thickener in eye drops to increase the viscosity and prolong the residence time of the drug in the eye, thus increasing the efficacy and reducing irritation.

PEG for Lubricants and Adhesives

PEG 4000 and PEG 6000 are typical representatives of water-soluble lubricants in tablets. An appropriate amount of polyethylene glycol can be added directly to the tablet prescription for granulation. It can also be prepared into an alcohol solution, suspension or emulsion for granulation without changing the lubrication effect. The disintegration and dissolution of tablets made with polyethylene glycol are not affected, which can improve the solubility of the main drug in the stomach, ultimately helping to increase bioavailability. In recent years, polyethylene glycols have become more and more widely used in tablets. They can be used not only as lubricants but also as binders, with PEG 4000 being the most commonly used.

PEG for lubricants and adhesives

For example, PEG 4000 is used as the binder (the melting point is low and it is molten under high-speed stirring), α-lactose is used as the filler, cross-linked polyvinylpyrrolidone is used as the disintegrant, and magnesium stearate is used as the lubricant. Carbamazepine immediate-release tablets can be prepared by granulation method. In addition, for heat-labile drugs, if PEG 4000 is used as a binder, the powder can be directly compressed into tablets in a dry state, and the effect is ideal.

PEG for Drug Carriers

As the molecular weight of PEG increases, it gradually changes from liquid to semi-solid to solid, and the melting point also increases. Since PEG is non-toxic and harmless to the human body, and has no side effects such as teratogenicity, carcinogenesis and genetic mutation, and can increase the dissolution rate of certain drugs and improve the bioavailability of drugs, it is one of the most commonly used water-soluble carriers.

PEG for Matrix

PEG is a type of hydrophilic matrix that is stable in nature, non-irritating to the skin, and has lubricity, so it is widely used in ointments, suppositories, gels, pills, and even capsules. For example, the water-sulfur ointment base is made by fusing PEG 300 and PEG 4000 in a 70°C water bath at a mass ratio of 2:1. Using PEG as the matrix, hydrogels, such as clonazepam hydrogel, can be prepared by adding the main drug and some pharmaceutical excipients. In addition, PEG 400, 1500, 4000~20000 can be used as a semi-solid matrix to convert hard capsules into liquid or semi-solid medicinal solutions.

PEG for Solid Dispersion Materials

The solid dispersion system refers to the dispersion system formed by the drug uniformly dispersed in a solid carrier material in a molecular, colloidal, amorphous, microcrystalline state. PEG (molecular mass 1,000-20,000) is a commonly used water-soluble carrier material that can be used to increase the dissolution rate of drugs. For example, using PEG 6000 as a carrier and using the melting method to prepare glibenclamide solid dispersion, its dissolution rate and bioavailability are significantly improved compared with commercially available Maninil. PEG can also be used as a carrier material for sustained-release solid dispersions. For example, the melting method is used to dissolve the drug in molten PEG, and the drug liquid is put into a hard capsule. The drug liquid solidifies at room temperature, and the drug is slowly released according to the dissolution mechanism, so it has a sustained release effect. In addition, the speed of drug dissolution from PEG carriers is mainly affected by the molecular weight of PEG. Generally, as the molecular weight of PEG increases, the drug dissolution rate will decrease. When the drug is oil, it is appropriate to use PEGs with larger molecular weights as carriers, such as PEG 12000 or a mixture of PEG 6000 and PEG 20000. If PEG 6000 alone is used as a carrier, the solid dispersion will become soft, especially at high temperatures, and the carrier will become sticky.

PEG for Capsule Material

Microcapsules are drug storage microcapsules that use natural or synthetic polymer materials (capsule materials) as capsule wall shells to wrap solid drugs or liquid drugs (capsule cores). PEG is a synthetic hydrophilic polymer material that can be used as a capsule material. For example, in vitro tests of ferrous sulfate microcapsules prepared with PEG 20000 as the capsule material show that about 90% of the drug is released within 5 minutes, and the remaining drugs are all released within 1 hour.

PEG for Framework Materials

High molecular weight PEG is a highly hydrophilic polymer material that can be used as a framework material to control the release rate of drugs. For example, sodium fluoride oral bioadhesive tablets prepared with CMC-Na, PEG 8000, carbomer 934, etc. as skeleton materials have good bioadhesion and sustained-release properties. Using dichloromethane as the solvent, inosine as the model drug, gelatin as the stabilizer, and a blend of β-hydroxybutyric acid (PHB) and PEG as the carrier (framework material), it was prepared by the double emulsion evaporation method. The obtained microspheres have obvious sustained release effect. In addition, PEG is widely used in the development of gel matrix tablets and anti-cancer drug magnetic microspheres.

What Can We Offer for PEG Manufacturing?

BOC Sciences' PEG products and services play a critical role in pharmaceutical formulation by providing high-quality materials and technical expertise to support drug development and manufacturing processes. PEG polymers, derivatives, and conjugates are versatile tools that can be used to enhance drug delivery, formulation, stability, and bioconjugation in pharmaceutical applications.

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BOC Sciences supplies a unique variety of PEG derivatives and functional PEG polymers. Our products offer the most diverse collection of reactivity, ready-to-use functionality, and molecular weight options that you will not find anywhere else.

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