developed during the 1870s in Rangoon, Burma by herbalist Aw Chu Kin, and brought to market by his sons. It is composed of 16% menthol and 28% oil of wintergreen. Watkins Liniment: One of Watkins Incorporated original products. Use on horses Liniments are commonly used on horses following exercise, applied either by rubbing on full-strength, especially on the legs; or applied in a diluted form, usually added to a bucket of water and sponged on the body. They are used in hot weather to help cool down a horse after working, the alcohol cooling through rapid evaporation, and counterirritant oils dilating capillaries in the skin, increasing the amount of blood releasing heat from the body. Many horse liniment formulas in diluted form have been used on humans, though products for horses which contain DMSO are not suitable for human use, as DMSO carries the topical product into the bloodstream. Horse liniment ingredients such as menthol, chloroxylenol, or iodine are also used in different formulas in products used by humans. Absorbine, a horse liniment product manufactured by W.F. Young, Inc., was reformulated for humans and marketed as Absorbine Jr. The company also acquired other liniment brands including Bigeloil and RefreshMint. The equine version of Absorbine is sometimes used by humans, though its benefits in humans may be because the smell of menthol releases serotonin, or due to a placebo effect. Earl Sloan was a US entrepreneur who made his initial fortune selling his father's horse liniment formula beginning in the period following the Civil War. Sloan's liniment, with capsicum as a key ingredient, was also marketed for human use. He later sold his company to the predecessor of Warner–Lambert, which was purchased in 2000 by Pfizer. References Drug delivery devices Dosage forms Ointments