Hexylene glycol is a small molecular weight surfactant. Hexylene Glycol is a solvent and viscosity agent used in many skin care products. Hexylene Glycol is a solvent and viscosity agent used in many skin care products. It is used to thin out heavy compositions and create a thinner, more spreadable product. Hexylene Glycol is a solvent and viscosity agent used in many skin care products. Hexylene glycol is used in the formulation of hair and bath products, eye and facial makeup, fragrances, personal cleanliness products, and shaving and skin care products. Hexylene glycol is widely used in the coating industry as a component for lacquers, varnishes, printing inks and both oil and water-based paints. Although the FDA has approved Hexylene Glycol and the CIR found it an acceptable solvent in skin care products, some studies have shown that it is an irritant.

Methyl pyrrolidone (or N-methyl pyrrolidone or NMP) is a small molecule acetyl‐lysine mimetic compound with potent immunomodulatory and direct anti‐myeloma activity. NMP is nontoxic, stable and already in use as a solvent in biomedical applications. This compound is under investigation in clinical trial phase I for the treatment of multiple myeloma. The study will evaluate if the NMP can be safely administered to humans at doses, which induce measurable immunological and anti-tumor effects in patients with myeloma. In addition, NMP could be useful for bone fracture repairing. NMP has shown a protective role in osteoblast differentiation in response to hypoxia, and such protection was through inhibiting the NF-κB signaling. Experiments on rodents have revealed that the compound had a remarkable anti-osteoporotic ability preserving activity in the pulp-dentine complex and preventing jawbone loss. These effects made NMP a promising candidate for the preservation of the activity of the pulp-dentin complex and jawbone thickness in post-menopausal females.