Aripiprazole-Associated Hypoprolactinemia in the Clinical Setting

Isolated hypoprolactinemia: The rarest of the rare?

Isolated hypoprolactinemia (IHP) can be defined as the presence of consistently low serum levels of prolactin in the absence of other anterior pituitary hormone abnormalities. It is an extremely rare condition, and consequently incompletely understood and unrecognized. A recent study has reported the first cases of IHP caused by mutation in the PRL gene. There are also cases where the pathogenesis of IHP is likely secondary to an autoimmune response against the PRL-secreting cells. But most published cases are acquired and idiopathic. The best characterized function of PRL is to facilitate milk production in the puerperium. Analysis of the GTEX data repository, however, shows that PRL is the most abundantly expressed gene in the human pituitary, independently of gender and age, suggesting the presence of additional roles for PRL. Newer studies have indeed revealed a much larger spectrum of PRL functions and will likely uncover novel clinical phenotypes associated with severe PRL deficiency.

Could low prolactin levels after radiotherapy predict the onset of hypopituitarism?

Both local and external cranial radiotherapy (RT) can induce neurotoxicity and vascular damage of the hypothalamic-pituitary area, which can promote neuroendocrine alterations. While anterior pituitary insufficiency after RT has been extensively characterized, data on the effect of RT on prolactin (PRL) secretion are limited and heterogeneous, with different patterns of PRL behavior described in the literature. A progressive decline in PRL levels, reflecting a time-dependent, slowly evolving radiation-induced damage to the pituitary lactotroph cells has been reported. To date, the association between hypopituitarism and hypoprolactinemia in patients undergoing RT has not yet been fully investigated. The few available data suggest that lower PRL levels can predict an extent damage of the pituitary tissue and a higher degree of hypothalamic dysfunction. However, most studies on the effect of RT on pituitary function do not properly assess PRL secretion, as PRL deficiency is usually detected as part of hypopituitarism and not systematically investigated as an isolated disorder, which may lead to an underestimation of hypoprolactinemia after RT. In addition, the often-inadequate follow-up over a long period of time may contribute to the non-recognition of PRL deficiency after RT. Considering that hypoprolactinemia is associated with various metabolic complications, there is a need to define appropriate diagnostic and management criteria. Therefore, hypoprolactinemia should enter in the clinical investigation of patients at risk for hypopituitarism, mainly in those patients who underwent RT.

Cardiometabolic effects of hypoprolactinemia

The fall of PRL levels below the lower limit of the normal range configures the condition of hypoprolactinemia. Unlike PRL excess, whose clinical features and treatments are well established, hypoprolactinemia has been only recently described as a morbid entity requiring prompt identification and proper therapeutic approach. Particularly, hypoprolactinemia has been reported to be associated with the development of metabolic syndrome and impaired cardiometabolic health, as visceral obesity, insulin-resistance, diabetes mellitus, dyslipidaemia, chronic inflammation, and sexual dysfunction have been found more prevalent in patients with hypoprolactinemia as compared to those with normoprolactinemia. This evidence has been collected mainly in patients on chronic treatment with dopamine agonists for PRL excess due to a PRL-secreting pituitary tumour, and less frequently in those receiving the atypical antipsychotic aripiprazole. Nowadays, hypoprolactinemia appears to represent a novel and unexpected risk factor for cardiovascular diseases, as is the case for hyperprolactinemia. Nevertheless, current knowledge still lacks an accurate biochemical definition of hypoprolactinemia, since no clear PRL threshold has been established to rule in the diagnosis of PRL deficiency enabling early identification of those individual subjects with increased cardiovascular risk directly ascribable to the hormonal imbalance. The current review article focuses on the effects of hypoprolactinemia on the modulation of body weight, gluco-insulinemic and lipid profile, and provides latest knowledge about potential cardiovascular outcomes of hypoprolactinemia.

Relationship Between Plasma Aripiprazole and Dehydroaripiprazole Concentrations and Prolactin Levels in Chinese Children and Adolescents

Objective: To investigate the relationship between plasma aripiprazole (ARI) and its metabolite dehydroaripiprazole (DARI) concentrations and prolactin (PRL) levels in Chinese children and adolescents. Methods: This was a retrospective cross-sectional study and the data were collected at Beijing HuiLongGuan Hospital, a Beijing City owned psychiatric hospital, between January 1 and December 31, 2021. Fifty-two child and adolescent inpatients (17 males, 35 females) aged 13-18 years and received ARI regardless of diagnosis were included. The steady-state ARI and DARI plasma concentrations were measured using high-performance liquid chromatography-tandem mass spectrometry. The serum PRL levels were measured by chemiluminescence immunoassay. Results: The plasma concentrations of ARI, DARI, and the total of ARI and DARI were negatively correlated with serum PRL levels in female children and adolescents. Approximately 15% of child and adolescent inpatients treated with ARI exhibited subnormal PRL serum levels. Conclusions: The results suggest that in addition to regularly monitoring PRL levels, therapeutic drug monitoring for ARI and its main metabolite DARI can help to mitigate the adverse medical consequences associated with PRL reduction. Thus, clinicians should consider the ARI-induced reduction of PRL levels when prescribing ARI to child and adolescent patients, particularly among females.

A Meta-Analysis of Antipsychotic-Induced Hypo- and Hyperprolactinemia in Children and Adolescents

Objective: Antipsychotic-related prolactin changes may expose children and adolescents to severe adverse reactions (ARs) related to pubertal development and growth. We therefore aimed to assess the effects of antipsychotics on prolactin levels and associated somatic ARs in children and adolescents. Methods: We systematically searched PubMed and CENTRAL for placebo-controlled randomized trials of antipsychotics in children and adolescents aged ≤18 years, reporting prolactin levels and related ARs. We conducted a random-effect meta-analysis and assessed risk of bias version 2 (ROB2). Results: Thirty-two randomized controlled trials with an average trial duration of 6 weeks, covering 4643 participants with an average age of 13 years and a male majority of 65.3%. Risk of bias across domains was low or unclear. The following antipsychotic compounds: aripiprazole (n = 810), asenapine (n = 506), lurasidone (n = 314), olanzapine (n = 179), paliperidone (n = 149), quetiapine (n = 381), risperidone (n = 609), and ziprasidone (n = 16) were compared with placebo (n = 1658). Compared with placebo, statistically significant higher prolactin increase occurred with risperidone (mean difference [MD] = 28.24 ng/mL), paliperidone (20.98 ng/mL), and olanzapine (11.34 ng/mL). Aripiprazole significantly decreased prolactin (MD = -4.91 ng/mL), whereas quetiapine, lurasidone, and asenapine were not associated with significantly different prolactin levels than placebo. Our results on ziprasidone are based on a single study, making it insufficient to draw strong conclusions. On average, 20.8% of patients treated with antipsychotic developed levels of prolactin that were too high (hyperprolactinemia), whereas only 1.03% of patients reported prolactin-related ARs. Data were highly limited for long-term effects. Conclusions: In children and adolescents, risperidone, paliperidone, and olanzapine are associated with significant prolactin increase, whereas aripiprazole is associated with significant decrease. Despite the significant changes in prolactin level, few ARs were reported. Study protocol on PROSPERO: CRD42018116451.

Relationship of Prolactin Concentrations to Steady-State Plasma Concentrations of Aripiprazole in Patients With Schizophrenia

BACKGROUND

Aripiprazole is regarded as the first-line antipsychotic medication. Long-term aripiprazole therapy can cause hypoprolactinemia, which may result from its activity as a dopamine agonist. However, there is little information on hypoprolactinemia and steady-state aripiprazole concentrations.

METHODS

The subjects included 66 male and 177 female patients diagnosed with schizophrenia who were treated with aripiprazole. The plasma concentrations of aripiprazole and dehydroaripiprazole and the plasma concentration of prolactin were measured using high-performance liquid chromatography and enzyme immunoassay, respectively. A prolactin concentration of <5 ng/mL was defined as hypoprolactinemia.

RESULTS

Fifty-two of the 66 male patients (79%) and 58 of the 177 female patients (33%) had hypoprolactinemia. There were significant inverse correlations between plasma prolactin levels and plasma concentrations of aripiprazole (rs = -0.447, P < 0.001) and the active moiety (aripiprazole plus dehydroaripiprazole) (rs = -0.429, P < 0.001) in men. In women, significant inverse correlations were also found between plasma prolactin levels and plasma concentrations of aripiprazole (rs = -0.273, P < 0.01) and the active moiety (rs = -0.275, P < 0.01).

CONCLUSIONS

These findings suggest that lower prolactin levels are, to some extent, associated with higher plasma drug concentrations in male and female patients with schizophrenia treated with aripiprazole.

Hypoprolactinemia and hyperprolactinemia in male schizophrenia patients treated with aripiprazole and risperidone and their relationships with testosterone levels

Aim

Several reports have shown that risperidone increases prolactin concentrations, while aripiprazole decreases prolactin concentrations. The frequency of abnormal prolactin concentrations in patients with schizophrenia receiving these drugs is still unknown. Furthermore, although hyperprolactinemia leads to sexual dysfunction, the relationship between hyperprolactinemia and testosterone, which may be directly related to male sexual function, is not well understood.

Methods

The subjects were 94 male schizophrenia outpatients receiving risperidone or paliperidone (risperidone group) and 83 male schizophrenia outpatients receiving aripiprazole. We measured the serum prolactin and total and free testosterone concentrations. We compared the prolactin and testosterone levels in patients receiving risperidone or paliperidone and patients receiving aripiprazole.

Results

The average serum prolactin concentration was 27.5 ± 13.1 ng/mL for the risperidone group and 3.9 ± 3.5 ng/mL for the aripiprazole group, and the concentrations were significantly different (P < .001). Hypoprolactinemia was observed in 75% of the aripiprazole group and hyperprolactinemia in 65% of the risperidone group. A positive correlation between prolactin levels and the risperidone daily dose was found, whereas a negative correlation between prolactin levels and the aripiprazole daily dose was observed. In the risperidone group, total testosterone concentrations were correlated with age, while free testosterone concentrations were inversely correlated with age and prolactin levels.

Conclusion

We found very common hyperprolactinemia and hypoprolactinemia in the risperidone or paliperidone group and aripiprazole group, respectively. Testosterone concentrations were associated with elevated prolactin levels in patients receiving risperidone or paliperidone. Further studies are needed to determine the clinical relevance of abnormal prolactin concentrations in male and female patients with schizophrenia.

There were very common hyperprolactinemia and hypoprolactinemia in the risperidone group and aripiprazole group, respectively. Free testosterone concentrations were associated with elevated prolactin levels in patients receiving risperidone or paliperidone.

Efficacy and Safety of Adjunctive Aripiprazole, Metformin, and Paeoniae-Glycyrrhiza Decoction for Antipsychotic-Induced Hyperprolactinemia: A Network Meta-Analysis of Randomized Controlled Trials

Aripiprazole, metformin, and paeoniae-glycyrrhiza decoction (PGD) have been widely used as adjunctive treatments to reduce antipsychotic (AP)-induced hyperprolactinemia in patients with schizophrenia. However, the comparative efficacy and safety of these medications have not been previously studied. A network meta-analysis of randomized controlled trials (RCTs) was conducted to compare the efficacy and safety between aripiprazole, metformin, and PGD as adjunctive medications in reducing AP-induced hyperprolactinemia in schizophrenia. Both international (PubMed, PsycINFO, EMBASE, and Cochrane Library databases) and Chinese (WanFang, Chinese Biomedical, and Chinese National Knowledge infrastructure) databases were searched from their inception until January 3, 2019. Data were analyzed using the Bayesian Markov Chain Monte Carlo simulations with the WinBUGS software. A total of 62 RCTs with 5,550 participants were included in the meta-analysis. Of the nine groups of treatments included, adjunctive aripiprazole (<5 mg/day) was associated with the most significant reduction in prolactin levels compared to placebo (posterior MD = -65.52, 95% CI = -104.91, -24.08) and the other eight treatment groups. Moreover, adjunctive PGD (>1:1) was associated with the lowest rate of all-cause discontinuation compared to placebo (posterior odds ratio = 0.45, 95% CI = 0.10, 3.13) and adjunctive aripiprazole (>10 mg/day) was associated with fewer total adverse drug events than placebo (posterior OR = 0.93, 95% CI = 0.65, 1.77) and other eight treatment groups. In addition, when risperidone, amisulpride, and olanzapine were the primary AP medications, adjunctive paeoniae/glycyrrhiza = 1:1, aripiprazole <5 mg/day, and aripiprazole >10 mg/day were the most effective treatments in reducing the prolactin levels, respectively. Adjunctive aripiprazole, metformin, and PGD showed beneficial effects in reducing AP-induced hyperprolactinemia in schizophrenia, with aripiprazole (<5 mg/day) being the most effective one.

Abnormally low prolactin levels in schizophrenia patients after switching to aripiprazole in a randomized trial: a biomarker for rebound in psychotic symptoms?

BACKGROUND

Switching to aripiprazole from other antipsychotics can avoid antipsychotic-induced hyperprolactinemia but may result in an abnormally low prolactin level. This study aimed to assess whether the aripiprazole-induced abnormally low prolactin level was a biomarker for subsequent rebound of positive symptoms in schizophrenia patients.

METHODS

Participants were 63 patients in an 8-week trial of switching to aripiprazole, in which preswitching antipsychotics were maintained for the first 2 weeks and aripiprazole was fixed at 15 mg orally throughout the trial. A prolactin level of < 3.7 ng/ml was defined as abnormally low, and an increase of two or more points in the positive subscore of the Positive and Negative Syndrome Scale at two adjacent ratings was defined as a psychotic rebound.

RESULTS

Among 63 patients, 25 (39.7%) had an abnormally low prolactin level and 21 (33.3%) had a psychotic rebound after switching to aripiprazole. In patients with abnormally low prolactin levels, 48.0% of them had a rebound in psychotic symptoms, whereas in those without abnormally low prolactin levels 23.7% did so. Multivariable logistic regression analysis with adjustment for sex, early age at onset, and preswitching medications revealed that abnormally low prolactin levels were associated with psychotic rebound (adjusted odds ratio = 3.55, 95% confidence interval = 1.02, 12.5). Furthermore, there was concurrency between the trend of the cumulative proportion of patients having an abnormally low prolactin level and that of the cumulative proportion of patients having a rebound in psychotic symptoms.

CONCLUSIONS

An abnormally low prolactin level after switching to aripiprazole in schizophrenia patients was a potential warning sign of a psychotic rebound. Hence, monitoring of prolactin levels after switching to aripiprazole may help avoid such rebound in schizophrenia.

TRIAL REGISTRATION

NCT00545467 ; Date of registration: 17/10/2007.

Safety and Tolerability of Antipsychotic Drugs in Pediatric Patients: Data From a 1-Year Naturalistic Study

Background: Antipsychotic drugs (APs) are increasingly used to treat a variety of psychiatric disorders in children and adolescents. However, their safety and tolerability profiles, when used in a developmental age context, show different characteristics from the ones observed in adult patients. Treatment with APs in pediatric patients is often long-term. However, the tolerability data regarding these patients mostly derive from short-term studies. Methods: Starting from April 2017, for a 1-year period, patients between 4 and 18 years of age followed by five units of developmental age neuropsychiatry, who initiated a treatment with at least an AP (ATC class N05A) were included into the study. Patient-related data have been collected at baseline and regularly thereafter, as allowed by the clinical routine. Changes to continuous variables over time have been analyzed using a linear mixed model in subsamples of our population treated with risperidone or aripiprazole. Results: During the observation period, 158 patients were initially enrolled, but only 116 completed 12 months of therapy with an AP. Risperidone was the most used AP (n = 52) followed by aripiprazole (n = 44) and olanzapine (n = 7). For both the aripiprazole and risperidone groups, the mean body mass index (BMI) (P < 0.001 for both groups) and heart rate (P = 0.026 for aripiprazole group and P < 0.001 for the risperidone one) values significantly increased over time. The mean prolactin concentration value significantly increased over time only in the risperidone group (P = 0.04). Eighty-six patients experienced at least one adverse drug reaction (ADR), accounting for a total of 238 specific reactions, with the most frequent being weight gain (n = 34), increased serum prolactin levels (n = 21), hyperphagia (n = 20), and hypercholesterolemia (n = 14). Among these, only 24 ADRs were classifiable as serious. Conclusions: The results of this study confirm that risperidone and aripiprazole are relatively well-tolerated therapeutic options for the treatment of a variety of psychiatric disorders in pediatric patients. However, in findings such as statistically significant increments of BMI and heart rate mean values, the variations over time in prolactin levels observed with risperidone and the differences between the two drugs remark the necessity of systematic monitoring.

TSH and PRL, side-effect markers in aripiprazole treatment: adjunctive aripiprazole-induced thyrotropin oversuppression in a young man with schizophrenia

A 26-year-old Japanese man was admitted to our unit with exacerbated paranoid schizophrenia. Prior to his admission, daily administration of olanzapine had been sufficient to maintain a partial remission of his schizophrenia, but due to an exacerbation of his delusions, he had then also been prescribed aripiprazole, which had been followed by no improvement in symptoms and a gradual further exacerbation of auditory delusions. Physical examinations, brain MRI and neurophysiological assessment were unremarkable. Blood analysis, however, revealed extremely low thyroid-stimulating hormone (TSH) and prolactin-releasing hormone (PRL) concentration. Interestingly, after aripiprazole discontinuation, he returned to partial remission with an increase in plasma TSH and PRL concentration.

Serum prolactin levels and sexual dysfunction in patients with schizophrenia treated with antipsychotics: comparison between aripiprazole and other atypical antipsychotics

OBJECTIVES

Antipsychotics, even atypical ones, can induce hyperprolactinemia. Aripiprazole (APZ), a dopamine D2 partial agonist, has a unique pharmacological profile and few side effects. We investigated the incidence of hyperprolactinemia in patients with schizophrenia treated with APZ and other antipsychotics.

METHODS

Serum prolactin levels were measured by ELISA (enzyme-linked immunosorbent assay). A questionnaire survey was used to evaluate subjective sexual dysfunction.

RESULTS

Based on the results of the questionnaire, approximately half (48.1%) of the patients complained of sexual dysfunction. The serum prolactin levels were significantly higher in patients with sexual dysfunction than in those without. In patients treated with antipsychotic monotherapy, the serum prolactin levels were significantly lower in patients treated with APZ than with other antipsychotics. In patients receiving 2 or more antipsychotics, the serum prolactin levels were significantly lower in patients treated with APZ-containing regimens than in patients treated with APZ-free regimens.

CONCLUSIONS

Treatment with APZ did not influence the serum prolactin level, and adjunctive treatment with APZ may ameliorate the hyperprolactinemia that occurs during monotherapy with other antipsychotics.