After Alexis Moussalli died in 1955, his heirs dismissed SECOR administrators, but the company faced increasing competition and lost market shares.
In 1962, the company was sold to Lafarge laboratories, which were in turn purchased by Sanofi in 1976. Lafarge closed the Vichy factory in 1965 and relocated to Châteauroux. With declining sales, the Tho-Radia brand was finally abandoned in 1968.