 By the 1980s, the use of amphetamines—particularly methamphetamine—as an adjunct to diet and exercise in the treatment of exogenous obesity had become frowned upon by many in the medical community.As the decades evolved, so did the composition of Obetrol.By 1995, the year Shire Pharmaceuticals (then known as Shire-Richwood) acquired Rexar Pharmacal, Obetrol 10 mg. and 20 mg. tablets contained, (in equal proportions)