Clonazepam (marketed by Roche under the trade-names Klonopin in the United States and Rivotril, Ravotril or Rivatril in Europe, South America, North America (Canada and Mexico), India, and Australia) is a drug which is a benzodiazepine derivative. It is a highly potent anticonvulsant, muscle relaxant and anxiolytic. Clonazepam is a chlorinated derivative of nitrazepamand a nitrobenzodiazepine like nitrazepam.

http://en.wikipedia.org/wiki/Clonazepam

Clonazepam, a benzodiazepine, is available as scored tablets with a K-shaped perforation containing 0.5 mg of clonazepam and unscored tablets with a K-shaped perforation containing 1 mg or 2 mg of clonazepam. Each tablet also contains lactose, magnesium stearate, microcrystalline cellulose and corn starch, with the following colorants: 0.5 mg—FD Yellow No. 6 Lake; 1 mg—FD Blue No. 1 Lake and FD Blue No. 2 Lake.

http://www.rxlist.com/cgi/generic/clonaz.htm