Acetylsalicylsalicylic acid is a commonly occurring impurity in commercial acetylsalicylic acid preparations. It is considered to be immunogenic substance.

Gentisic acid is an active metabolite of salicylic acid degradation, which possesses a broad spectrum of biological activity, such as anti-inflammatory, antirheumatic and antioxidant properties. The antioxidant activity and radioprotective properties of gentisic acid are exerted by its phenoxyl group. It is also used in cosmetics as a skin-whitening agent for the treatment of skin pigmentary disorders by influencing the synthesis of melanin through inhibition of melanosomal tyrosinase activity Gentisic acid is also a biomarker of Renal Cell Carcinoma.

Butylated hydroxytoluene, commonly known as BHT, is an organic compound that is used in the food, cosmetic, and pharmaceutical industry as an antioxidant. BHT is a substituted derivative of phenol. BHT helps to prevent the formation of free radicals and oxidation. When used in food products, it delays oxidative rancidity of fats and oils, and prevents loss of activity of oil-soluble vitamins. It may be found in pharmaceutical gels, creams and liquid or gelatin capsules, tablets and other pharmaceutical dosage forms. The ability of oral BHT to lead to cancer is a controversial topic, but most food industries have replaced it with butylated hydroxyanisole (BHA). BHT was first used as an antioxidant food additive in 1954. BHT does have other commercial uses, as in animal feeds and in the manufacture of synthetic rubber and plastics, where it also acts as an antioxidant. The U.S. Food and Drug Administration has deemed that BHT is safe enough when used in limited concentrations. It currently permits its use in concentrations of about 0.01% to 0.02% in most foods. As an emulsion stabilizer in shortening, it may be used in a somewhat higher concentration, 200 parts per million.

Etoperidone is an atypical antidepressant introduced in Europe in 1977. The activity of etoperidone is made mainly by its major metabolite 1-(3'-chlorophenyl)piperazine (mCPP). mCPP binds with different affinity to most of the serotonergic receptors and adrenergic receptors. This metabolite is an agonist of 5-HT2c and an antagonist of 5-HT2a. Part of etoperidone structure contributes to the activity in the α-adrenergic receptors. Etoperidone has been studied for the treatment of depression, tremors in Parkinson, extrapyramidal symptoms and male impotence. It is not certain if it was ever approved and marketed but its current status is withdrawn.

Methylbenzethonium chloride is a quaternary ammonium with antimicrobial activity, which is used in combination with aminoglycoside antibiotic, paromomycin (brand name LESHCUTAN) for the topical treatment of cutaneous leishmaniasis.

Amylmetacresol (AMC) is an antiseptic used to treat infections of the mouth and throat. It is used as an active pharmaceutical ingredient in Strepsils, Gorpils and Lorsept throat lozenges. It was shown that the presence of amylmetacresol, dichloro-benzylalcohol and lidocaine block of inward sodium current.