Schizophrenia is a debilitating mental illness that affects patient’s function and quality of life. Estimates indicate a lifetime prevalence of 0.48%, causing up to 13.4 million years of life burdened by disability. 30% of these patients are deemed as having treatment-resident schizophrenia (TRS), a subset of which do not respond to clozapine, the medication designated for TRS. Those that do not respond to clozapine are deemed to have clozapine-resistant schizophrenia (CRS), requiring further augmentation or multiple antipsychotics.

Clozapine only has limited formulations available (oral [PO] and dissolving [ODT]) and has a substantial side effect burden. Most serious among these side effects includes agranulocytosis, which in some cases can cause severe infections such as septicemia. Regular blood draws monitoring for this are vital to prevent this dangerous consequence, but place further burden on patients, requiring weekly to monthly lab work and visits. Other common and burdensome side effects include tachycardia, hypotension, sialorrhea, weight gain, and metabolic syndrome, to name a few. However, treatment for TRS is still needed, and further alternatives must be explored.

Among studies done on clozapine, few compare second-generation antipsychotics head-to-head, and those that do find similar improvement in overall symptom burden among multiple antipsychotics, especially olanzapine and paliperidone (in particular, paliperidone palmitate). Due in part to the improved receptor profile of these medications (especially 5-HT2A, 6, and 7) compared to clozapine, they can have similar or superior effect in patients with TRS without substantial patient side effect and functional burden. Paliperidone palmitate formulations are developing that can be spaced further and further apart, allowing for minimal impact on patient’s livelihood, while demonstrating similar overall effect with improved side effect profile. However, onset of action is slow, and an effective adjunct strategy may be to initially administer olanzapine for the first 6 months until peak effect is expected from paliperidone palmitate, at which point monotherapy with paliperidone is preferred.

Alternative therapies for patients with TRS may be more functional with fewer side effects, and this work indicates a particularly effective strategy may be to pursue paliperidone palmitate monotherapy long-term while utilizing the unique combination of paliperidone and olanzapine in the short-term (first 6 months) while awaiting peak efficacy.

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