Loxapine, Thiothixene, Trifluoperazine

Beyond the major FGAs sit a handful of niche agents that have specific roles modern psychiatry still uses. The most clinically relevant are inhaled loxapine, pimozide, and the older agents trifluoperazine and thiothixene.

Inhaled loxapine — Adasuve — is one of the more interesting innovations in acute agitation management. Loxapine itself is a mid-potency FGA with some 5-HT2A activity (blurring the FGA/SGA line). The inhaled formulation produces antipsychotic effect within approximately ten minutes — comparable to IM haloperidol, with a route the cooperative patient may prefer over an injection. The cost is REMS administration in a certified setting due to bronchospasm risk; rescue equipment and a healthcare professional trained in airway management must be available. Avoid in active reactive airway disease.

Pimozide is the niche agent for Tourette syndrome. It is uniquely effective for some patients with Tourette, sometimes outperforming haloperidol. The mechanism is high-potency D2 antagonism with substantial QTc prolongation, so baseline ECG and periodic monitoring are required, particularly with CYP3A4 inhibitors that raise pimozide levels. Drug interaction screening is essential.

Trifluoperazine and thiothixene are older high-potency FGAs that remain in use mostly as legacy treatment in chronic schizophrenia. Their profiles are similar to fluphenazine — substantial EPS, prolactin elevation, low sedation and metabolic burden. New starts are rare; established responders sometimes continue.

For each of these niche agents, the question is whether there's a specific clinical reason — inhaled route, Tourette response, historical response — that makes this agent the right one. For most patients, broader-use SGAs or the major FGAs cover the clinical need.