In 1959, Brockham Park became famous when Beecham scientists there discovered the
penicillin nucleus,
6-APA (6-aminopenicillanic acid); This discovery allowed Beecham, working in tandem with
Bristol-Myers, to synthesize a number of new semisynthetic penicillins. Beecham marketed Broxil (
phenethicillin), followed shortly by the more potent Celbenin (
methicillin), which was active against
Staphylococcus aureus. The group continued to focus on pharmaceutical development, producing further semi-synthetic penicillins. However, when Penbritin (
ampicillin) came on the market in 1961, Beecham's facilities were soon inadequate for the worldwide demand for the drug. A complex at
Worthing came on line in the early 1960s, to produce phenethicillin, followed by the ability to produce 6-APA, the base for semisynthetic penicillins. The company continued to add products, and acquire other companies, through the 1970s and 1980s. In 1971, the
S. E. Massengill Company was acquired. Beecham launched Amoxil (
amoxicillin) in 1972, which went on to become one of the most widely prescribed antibiotics. for US$100 million (approximately £59 million), which included brands
Aqua Velva,
Geritol, and
Sominex − the U.S. formulation − along with others. ==Later history==