Which psychiatric drug does not need any test dose before starting the routine dose?

Correct option is B

Risperidone does not require a test dose because it has a relatively predictable safety profile and a lower risk of severe immediate adverse reactions when started at standard initial doses. It is usually begun at a low dose and then gradually increased (titrated), but this is for optimizing effectiveness and minimizing mild side effects—not because a test dose is necessary.

In contrast, Clozapine requires very careful initiation and monitoring because of the risk of agranulocytosis (a serious drop in white blood cells), so baseline and regular blood tests are essential. Haloperidol may sometimes need a test dose (especially injectable forms) to assess for extrapyramidal side effects or sensitivity, and Quetiapine is started gradually due to risks like sedation and orthostatic hypotension.