A pain medication so old that “Mad Men” might have concocted its first advertising campaign might be the cure for more than 500,000 people worldwide whose tuberculosis has grown resistant to front-line antibiotics, a new study says. Oxyphenbutazone, an anti-inflammatory medication marketed in the 1950s as Tandearil and still used in veterinary medicine, put on a spectacular test-tube display of attacking both forms of the TB bacterium — those that replicate and those that do not.