Influence of CYP2D6 Metabolizer Status on Risperidone and Paliperidone Tolerability in Children and Adolescents.

Background: Risperidone and, to a lesser extent, paliperidone are metabolized by CYP2D6; however, there are limited data related to variation in CYP2D6 phenotypes and the tolerability of these medications in children and adolescents. Furthermore, the impact of CYP2D6 on the association of risperidone and paliperidone with hyperprolactinemia in youth is not well understood. Methods: A retrospective chart review was performed in psychiatrically hospitalized children and adolescents prescribed risperidone (n = 263, age = 3-18 years, mean age = 13 ± 3 years, 49% female) or paliperidone (n = 124, age = 5-18 years, mean age = 15 ± 2 years, 44% female) who had CYP2D6 genotyping performed as part of routine care. CYP2D6 phenotypes were determined based on Clinical Pharmacogenetics Implementation Consortium guidelines and CYP2D6 inhibitors causing phenoconversion. Adverse effects were obtained from a review of the electronic health record, and patients were selected, in part, to enrich non-normal metabolizers. Results: Among risperidone-treated patients, 45% experienced an adverse effect, whereas 36% of paliperidone-treated patients experienced adverse effects. Discontinuation of risperidone due to lack of efficacy was more frequent in the CYP2D6 normal metabolizers and ultrarapid metabolizers compared with intermediate metabolizers (IMs) and phenoconverted poor metabolizers (pPMs) (54.5% vs. 32.7%, p < 0.001). Discontinuation due to weight gain was more common among risperidone- than paliperidone-treated patients (17% vs. 7%, p = 0.011). Among those taking paliperidone, CYP2D6 was associated with discontinuation due to side effects (p = 0.008), and youth with slower CYP2D6 metabolism (i.e., pPMs and IMs) were more likely to discontinue. Hyperprolactinemia was found in 10% of paliperidone-treated patients and 5% of risperidone-treated patients, and slower CYP2D6 metabolizers required higher risperidone doses to cause hyperprolactinemia (p = 0.011). Conclusions: CYP2D6 phenotype is associated with discontinuation of risperidone due to lack of efficacy and the dose of risperidone that induced hyperprolactinemia, as well as discontinuation of paliperidone due to adverse effects. Future studies should evaluate exposure-response and toxicity relationships in risperidone- and paliperidone-treated youth.

Identificação de genes diferencialmente expressos em prolactinomas resistentes e sensíveis aos agonistas dopaminérgicos / Identification of genes differentially expressed in prolactinomas resistant and responsive to dopamine agonists

Como os mecanismos envolvidos na resistência dos prolactinomas aos agonistas dopaminérgicos (AD) ainda não foram completamente elucidados, o objetivo deste estudo foi obter novas informações sobre as diferenças moleculares que existem entre prolactinomas sensíveis e resistentes aos AD. Avaliamos a expressão de 7 genes pela Reação de Polimerase em cadeia em tempo real: receptor de dopamina tipo 2, fator de crescimento do nervo beta e seu receptor, receptor de estrógeno alfa e beta, pituitary tumor transforming gene e metalotioneína 3 em tecido tumoral de 22 pacientes. Os pacientes foram classificados como sensíveis ou resistentes aos AD de acordo com sua resposta clínica e laboratorial aos AD e a expressão gênica foi comparada a esta classificação / As the mechanisms involved in the resistance of prolactinomas to dopamine agonist (DA) are not fully understood, the aim of this study was to get new insights in molecular differences between prolactinomas responsive and resistant to DA. We evaluated the expression of 7 genes by Real Time Polimerase Chain Reaction: dopamine receptor type 2, nerve growth factor beta and its receptor, estrogen receptor alfa and beta, pituitary tumor transforming gene and methalotionein 3 in tumor tissue of 22 patients. Patients were classified as responsive or resistant to DA accordingly to their clinical and laboratorial response and gene expression was compared to this classification...