Efficacy and safety of high-dose antipsychotic therapy

Compared with other antipsychotics, high-dose clozapine and quetiapine may be less likely to cause EPS due to lower D2 receptor occupancies.⁴⁰ Nevertheless, increased activity at other postsynaptic receptors may lead to constipation, metabolic effects, and sedation.^1,41,42 Case reports suggest efficacy with quetiapine, 1,200 to 2,400 mg/d, vs lower dosages for patients with TRS.^43,44 However, RCTs of quetiapine, 600 and 800 mg/d vs 1,200 mg/d, have not demonstrated an efficacy advantage with high-dose treatment in patients with schizophrenia or schizoaffective disorder.^41,45 High-dose quetiapine has also resulted in photopsia, cardiotoxicity, orthostasis, dysphagia, and sedation.^43,46,47

Proceed with caution

In light of safety concerns and a lack of high-quality evidence for high-dose antipsychotic therapy, alternative solutions for inadequate response to treatment should be considered. Underlying causes of poor response should be addressed, and alternative antipsychotics should be utilized, when appropriate. A clozapine trial remains first-line for TRS. Olanzapine may be the best-supported high-dose antipsychotic alternative when clozapine is not an option. High antipsychotic dosages are not well-studied in patients with genetic polymorphisms or unavoidable drug interactions. Serum antipsychotic concentrations may facilitate dosing in these patients.

If high-dose antipsychotic therapy is deemed necessary, its ongoing appropriateness should be continually re-evaluated. Higher antipsychotic dosages and D2 receptor occupancies may be required to manage acute psychosis, but efficacy may be maintained and adverse effects limited with the use of lower dosages during maintenance treatment.^48,49 Long-term treatment with high-dose antipsychotic therapy should be avoided, when possible. If high-dose antipsychotic therapy is prescribed, the rationale should be well-documented. Dosage adjustments should not be made until steady state is reached on a given dosage. Electrocardiograms should be obtained at baseline, steady state, and routinely thereafter.^3,20 Tolerability should be assessed regularly, and screening for drug interactions should be conducted when new medications are initiated.

Case CONTINUED

Because Mr. K’s serum risperidone level is subtherapeutic (10 ng/mL), his risperidone dosage is cautiously titrated to 10 mg/d, divided (serum concentration: 22 ng/mL). Mr. K develops mild orthostasis but denies other adverse effects. His psychotic symptoms resolve, and he is discharged with education on nonpharmacologic management of orthostasis. The rationale for high-dose risperidone is relayed to his outpatient psychiatrist, as well as a recommendation to monitor Mr. K closely for continued efficacy and tolerability.

Related Resource

• Barnes TRE, Drake R, Paton C, et al. Evidence-based guidelines for the pharmacological treatment of schizophrenia: updated recommendations from the British Association for Psychopharmacology. J Psychopharmacol. 2020;34(1):3-78.

Drug Brand Names

Aripiprazole • Abilify
Asenapine • Saphris
Brexpiprazole • Rexulti
Cariprazine • Vraylar
Clozapine • Clozaril
Iloperidone • Fanapt
Lumateperone • Caplyta
Lurasidone • Latuda
Olanzapine • Zyprexa
Paliperidone • Invega
Quetiapine • Seroquel
Risperidone • Risperdal
Risperidone long-acting injection • Risperdal Consta
Ziprasidone • Geodon