All of the following are benzodiazepines EXCEPT:

Benzodiazepines are a class of medications primarily used for their sedative, anxiolytic, muscle relaxant, and anticonvulsant properties. The primary examples of benzodiazepines include substances such as diazepam, alprazolam, and lorazepam, all of which act on the central nervous system by enhancing the effect of the neurotransmitter gamma-aminobutyric acid (GABA).

Yohimbine, on the other hand, is not a benzodiazepine. It is an alkaloid derived from the bark of the yohimbe tree and is primarily used as an aphrodisiac and for its stimulant effects. Yohimbine acts on the central nervous system but does not share the same pharmacological properties or mechanisms of action as benzodiazepines. This distinction is crucial, as benzodiazepines are indicated for anxiety and related disorders, while yohimbine has a different therapeutic use and action.

Understanding the classification and pharmacological actions of these compounds is important in veterinary pharmacology, as it helps in the selection of appropriate medications for treating various conditions in animals.