It was the first organic peroxide prepared intentionally.In 1901, J. H. Kastle and his graduate student A. S. Loevenhart observed that the compound made the tincture of guaiacum tincture turn blue, a sign of oxygen being released. Around  1905, Loevenhart reported on the successful use of BPO to treat various skin conditions, including burns, chronic varicose leg tumors, and tinea sycosis. He also reported animal experiments that showed the relatively low toxicity of the compound.Treatment with benzoyl peroxide was proposed for wounds by Lyon and Reynolds in 1929, and for sycosis vulgaris and acne varioliformis by Peck and Chagrin in 1934. However, preparations were often of questionable quality. It was officially approved for the treatment of acne in the US in 1960. Medical uses
Acne treatment
Benzoyl peroxide is effective for treating acne lesions. It does not induce antibiotic resistance. It may be combined with salicylic acid, sulfur, erythromycin or clindamycin (antibiotics), or adapalene (a synthetic retinoid). Two common combination drugs include benzoyl peroxide/clindamycin and adapalene/benzoyl peroxide, adapalene being a chemically stable retinoid that can be combined with benzoyl peroxide unlike tezarotene and tretinoin. Combination products such as benzoyl peroxide/clindamycin and benzoyl peroxide/salicylic acid appear to be slightly more effective than benzoyl peroxide alone for the treatment of acne lesions. The combination tretinoin/benzoyl peroxide was approved for medical use in the United States in 2021. Benzoyl peroxide for acne treatment is typically applied to the affected areas in gel, cream, or liquid, in concentrations of 2.5% increasing through 5.0%, and up to 10%.
XXY males have a ~15-fold higher risk of developing breast cancer than typical, but still lower than that of females. People with the condition have a nearly normal life expectancy.Klinefelter syndrome is one of the most common chromosomal disorders, occurring in one to two per 1,000 live male births. It is named after American endocrinologist Harry Klinefelter, who identified the condition in the 1940s. In 1956, the extra X chromosome was identified as the cause. Mice can also have the XXY syndrome, making them a useful research model. Signs and symptoms
The primary features are infertility and small, poorly functioning testicles. Often, symptoms may be subtle and many people do not realize they are affected. Sometimes, symptoms are more prominent and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and low libido. Often, these symptoms are noticed only at puberty. Prenatal
An estimated 60% of fetuses with Klinefelter syndrome end in miscarriage. Physical
As babies and children, XXY males may have weaker muscles and reduced strength. As they grow older, they tend to become taller than average. They may have less muscle control and coordination than other boys of their age.During puberty, the physical traits of the syndrome become more evident; because these boys do not produce as much testosterone as other boys, they have a less muscular body, less facial and body hair, and broader hips.