Polyethylene glycol 400 (PEG 400) is indeed a liquid polyethylene glycol (PEG) excipient grade product. PEGs are a group of synthetic polymers with various molecular weights, and they are commonly used in pharmaceuticals, cosmetics, and other industries for their unique properties.

PEG 400 is one specific member of the PEG family, and it is characterized by its relatively low molecular weight and liquid form at room temperature. It is widely used in the pharmaceutical industry as an excipient, which means it is added to formulations to serve various functions such as:

1. Solubilizing agent: PEG 400 can enhance the solubility of poorly water-soluble drugs in both liquid and solid formulations, making it easier to formulate medications.

2. Lubricant: It can be used as a lubricant in the manufacture of tablets and capsules to facilitate their production and prevent sticking.

3. Plasticizer: PEG 400 can be added to semi-solid and solid dosage forms to modify their physical properties, such as improving the flexibility of suppositories.

4. Solvent: It serves as a solvent for various active pharmaceutical ingredients (APIs) and excipients in liquid formulations.

5. Vehicle for oral solutions: PEG 400 is often used as a vehicle for oral solutions, suspensions, and elixirs.