Pharmacokinetics of the novel antipsychotic agent risperidone and the prolactin response in healthy subjects

The pharmacokinetics of a novel antipsychotic agent, risperidone, and the prolactin response were studied in 12 dextromethorphan-phenotyped healthy men after administration of 1 mg risperidone intravenously, intramuscularly, and orally. The formation of the equipotent major metabolite, 9-hydroxyrisperidone, exhibited CYP2D6-related polymorphism. The plasma area under the concentration-time curve from time zero to infinity ratio of 9-hydroxyrisperidone to risperidone averaged 3 (intravenous and intramuscular) and 6 (oral administration) in the extensive metabolizers and 0.2 in the poor metabolizers. Risperidone half-life was about 3 hours in extensive metabolizers and 22 hours in poor metabolizers. Risperidone absolute oral bioavailability was 66%. The pharmacokinetics of the active moiety (risperidone plus 9-hydroxyrisperidone) varied little among subjects (mean terminal half-life, 20 +/- 2 1/2 hours; absolute oral and intramuscular bioavailability, 100%). The prolactin response correlated best with the plasma active moiety, which showed little hysteresis. It is concluded that risperidone metabolic polymorphism on increased plasma prolactin is minimal and that the active moiety is clinically relevant.

Somatostatin receptor subtype specificity in human fetal pituitary cultures. Differential role of SSTR2 and SSTR5 for growth hormone, thyroid-stimulating hormone, and prolactin regulation

Somatostatin (SRIF), a hypothalamic inhibitor of pituitary growth hormone (GH) and thyroid-stimulating hormone (TSH) secretion, binds to five distinct receptor (SSTR) subtypes. We therefore tested SSTR subtype-specific SRIF analogs in primary human fetal pituitary cultures (23-25-wk gestation) to elucidate their role in regulating human pituitary function. Using reverse transcription-PCR, mRNA expression of SSTR2 and SSTR5 were detected in fetal pituitary by 25 wk. SRIF analog affinities were determined by membrane radioligand binding in cells stably expressing the human SSTR forms. GH secretion was suppressed equally (40-60%, P < 0.005) by analogs preferential for either SSTR2 (IC50 for receptor binding affinity, 0.19-0.42 nM) or SSTR5 (IC50, 0.37 nM), and compounds with enhanced affinity for SSTR2 were more potent (EC50 for GH suppression, 0.05-0.09 nM) than Lanreotide (EC50, 2.30 nM) and SRIF (EC50, 0.19 nM). Similarly, analogs with high affinity for SSTR2 or SSTR5 decreased TSH secretion (30-40%, P < 0.005). However, prolactin was effectively inhibited only by compounds preferentially bound to SSTR2 (20-30%, P < 0.05). Luteinizing hormone was modestly decreased (15-20%) by SSTR2- or SSTR5-specific analogs. An SSTR5-specific analog also exclusively inhibited GH in acromegalic tumor cells. Thus, SRIF regulation of GH and TSH in primary human fetal pituitary cells is mediated by both SSTR2 and SSTR5, both of which are abundantly expressed by 25 wk. In contrast, suppression of prolactin is mediated mainly by SSTR2. These results indicate that SSTR5 is critical for physiologic regulation of GH and TSH. SRIF analogs with selective affinity for this receptor may therefore be more effective in the treatment of hormone-secreting pituitary adenomas.

Spectrum of subclinical and overt hypothyroidism: effect on thyrotropin, prolactin, and thyroid reserve, and metabolic impact on peripheral target tissues

PURPOSE

Subclinical hypothyroidism is found in about 7.5% of females and in about 3% of males. It appears to be a risk factor for atherosclerosis and for coronary heart disease and can affect various other target organs. The morbidity and clinical significance of subclinical hypothyroidism are controversial. Therefore, we evaluated the metabolic impact of progressive thyroid failure in patients with various degrees of hypothyroidism compared with control subjects.

PATIENTS AND METHODS

We investigated 86 female patients with the whole spectrum of subclinical hypothyroidism (n = 69) and of overt hypothyroidism (n = 17) and 52 euthyroid women as controls. All subjects underwent full medical and endocrine evaluations (including measurements of thyrotropin [TSH], TSH beta- and alpha-subunits, and prolactin before and after oral administration of thyrotropin-releasing hormone [TRH]) as well as lipid profiles and different tests of peripheral thyroid hormone action. All hypothyroid patients were divided into five categories according to disease severity: grades I to III (subclinical hypothyroidism, with normal thyroxine [T4] levels) and grades IV and V (overt hypothyroidism, with diminished T4).

RESULTS

In grade I subclinical hypothyroidism (basal TSH below 6 mU/L), we found significant changes in the clinical index (p less than 0.05), apoprotein A-I level (p less than 0.05), and stimulated prolactin level after oral TRH (p less than 0.001). The findings were similar in grade II (TSH 6 to 12 mU/L). Further changes could be demonstrated in grade III (TSH above 12 mU/L) with a definite elevation of ankle reflex time (p less than 0.001), serum myoglobin level (p less than 0.01), and, to a lesser extent, creatine kinase (p greater than 0.1). The mean low-density lipoprotein cholesterol (LDL-C) level showed an increase of 18%, which was not significant because of marked individual variations (p = 0.15). The frequency of elevated LDL-C levels was definitely higher in patients with grade III disease compared with the controls (42.9% versus 11.4%, p less than 0.05) and with patients with grades I and II disease. Total cholesterol, triglycerides, apoprotein B, and the systolic time intervals (pre-ejection period, corrected for heart rate [PEPc]) were clearly elevated only in overt hypothyroidism (grades IV and V) (p less than 0.01).

CONCLUSION

Subclinical hypothyroidism has significant effects on some peripheral target organs at an early stage (grades I and II), but affects LDL-C, skeletal muscle, and myocardial contractility only at a later stage (grades III, IV, and V). Our data of elevated LDL-C in grade III subclinical hypothyroidism provide a likely pathophysiologic explanation for the reported association of coronary heart disease with this syndrome. The impact of increased prolactin secretion, observed in subclinical hypothyroidism, on gonadal function and infertility has yet to be clarified. Therapy with thyroxine should be recommended in at least some patients with subclinical hypothyroidism. Patients with high TSH levels (above 12 mU/L) will require treatment because of the metabolic effects on several target organs. Before treatment is advocated in all patients with subclinical hypothyroidism, the benefits and long-term side effects of thyroid hormone therapy should be clarified by prospective studies in larger groups of patients.

Progesterone-dependent decidualization of the human endometrium is mediated by cAMP

Progesterone is a key factor in regulating endometrial cell decidualization, but the signal transduction pathways involved in mediating the effects of progesterone are not known. A role of the cAMP pathway in decidualization has been suggested by in vitro studies demonstrating that cAMP agonists can stimulate decidualization, in the absence of sex steroids. In this article, we have used an in vitro culture model of progesterone-dependent decidualization of human endometrial stromal cells to examine whether progesterone-induced decidualization is associated with activation of the cAMP signal transduction pathway in which the prolactin gene expression is a marker of decidualization. Following a lag period of approx 3 d, progesterone induced prolactin secretion and elevated intracellular cAMP levels. By d 15, cAMP and prolactin levels were approx 10- and 60-fold greater, respectively, than those on d 3. Changes in cAMP levels showed a positive correlation with prolactin secretion. Prostaglandin E2 (PGE2), which enhances progesterone-dependent decidualization, also increased both prolactin secretion and cAMP levels approx two- to fourfold on d 15 compared with d 3, whereas PGE2 alone, which does not induce decidualization, did not stimulate prolactin secretion or intracellular cAMP accumulation. Conversely, all-trans retinoic acid, which attenuates progesterone-dependent decidualization, significantly (p < 0.05) decreased both prolactin secretion and cAMP levels. Furthermore, the protein kinase A (PKA) inhibitor, 8-bromoadenosine-3',5'-cyclic monophosphorothioate, significantly (p < 0.05) suppressed progesterone-dependent prolactin expression. Since activation of the PGE2 receptor subtype EP2 stimulates adenylate cyclase, reverse transcription-polymerase chain reaction (RT-PCR) analysis of endometrial cells was undertaken. Expression of EP2 mRNA was induced in cells treated with progesterone and estradiol alone or with PGE2, compared with untreated controls. The data suggest that the cAMP signal transduction cascade is activated during progesterone-dependent decidualization.

Mechanism of new antipsychotic medications: occupancy is not just antagonism

Antagonism of D2-like dopamine receptors is the putative mechanism underlying the antipsychotic efficacy of psychotropic drugs. Positron emission tomographic studies suggest that the antipsychotic effect of dopamine receptor antagonists occurs within a therapeutic window between 60% and 80% (striatal) D2 receptor occupancy. The incidence of extrapyramidal side effects increases above the 80% threshold. However, the novel atypical antipsychotic drug, aripiprazole, occupies up to 95% of striatal D2-like dopamine receptors at clinical doses, and the incidence of extrapyramidal side effects with aripiprazole is no higher than with placebo. The most likely explanation for this finding is aripiprazole's weak partial agonism at D2-like dopamine receptors. This particular pharmacologic feature characterizes a new class of atypical antipsychotics that does not match the original concept of a therapeutic occupancy window for antagonist antipsychotics. When not involving pure antagonists, it implies a need to adjust the expected receptor occupancy (measured using positron emission tomography) for the therapeutic window.

Impulsive aggression and central serotonergic system function in humans: an example of a dimensional brain-behavior relationship

A dimensional relationship between central serotonergic (5-HT) system function and indices of suicidal and impulsive aggressive behaviors has been suggested by more than a decade of research in patients with psychiatric disorders. This paper reviews a series of studies conducted in healthy male individuals and in male patients with major mood and/or personality disorder involving pharmacochallenge and neurochemical strategies designed to explore the role of central 5-HT system function in the regulation of suicidal and impulsive aggressive behavior in humans. The results of these studies suggest that reduced overall central 5-HT function in the limbic-hypothalamic system is associated with suicidal and/or impulsive aggressive behaviors in patients with major mood and/or personality disorders and that diminished 5-HT post-synaptic receptor function in this brain region may be an important biological correlate of these behaviors.

Risk of hip fracture in patients with a history of schizophrenia

BACKGROUND

There is evidence of an association between decreased bone mineral density, schizophrenia, and prolactin-raising antipsychotic medication. However, it is not known whether this is clinically significant.

AIMS

To investigate whether patients with a history of schizophrenia are at increased risk of hip fracture.

METHOD

In a case-control study, we compared cases of 'hip fracture' on the General Practice Research Database (n=16,341) with matched controls (n=29,889).

RESULTS

Hip fracture was associated with schizophrenia (OR=1.73; 95% CI 1.32-2.28), and prolactin-raising antipsychotics (OR=2.6; 95% CI 2.43-2.78), in the univariate analysis. In the multivariate analysis, prolactin-raising antipsychotics were independently associated with hip fracture but schizophrenia was not. A significant interaction between gender and antipsychotics was foundinthe association with hip fracture (P=0.042); OR=2.12 (95% CI1.73-2.59) for men, OR=1.93 (95% CI1.78-2.10) for women.

CONCLUSIONS

The association between prolactin-raising antipsychotic medication and hip fracture may have serious implications for public health. Mental health service patients may require preventive measures including dietary and lifestyle advice.

Atypical antipsychotics: are some more atypical than others?

On the heels of clozapine, we now have a number of newer agents (risperidone, olanzapine, quetiapine, sertindole, and ziprasidone). Are they all the same? What are the differences? How do we best understand them? In this article we review current clinical evidence to compare these issues on four measures of atypicality: EPS, prolactin elevation, superior efficacy in refractory/positive symptoms and efficacy against negative symptoms. All the newer agents are superior on EPS and, with the exception of risperidone, avoid prolactin elevation. Clozapine shows the most convincing efficacy in refractory schizophrenia, although comparative data concerning risperidone's benefit in this respect are also emerging. It is unclear, however, whether any of the agents produce a greater effect than conventional antipsychotics against positive symptoms in responsive patients. Both clozapine and olanzapine have demonstrated superior efficacy against negative symptoms, although it remains controversial whether this is an effect on primary or secondary symptoms. The precise pharmacologic mechanisms underlying "atypicality" remain unclear, but several conceptual frameworks are highlighted that characterize, and perhaps differentiate, these newer agents.

Neuropeptide Y promotes sleep and inhibits ACTH and cortisol release in young men

Anxiolytic and sedative effects of neuropeptide Y (NPY) are thought to involve inhibition of corticotropin-releasing hormone (CRH). Enhanced secretion of CRH plays a critical role in the pathophysiology of major depression, characterized by sleep disturbances, anxiety and loss of appetite. We examined for the first time in young men effects of intravenous injections of NPY (4x50 or 100 microg, n = 9 and 11, respectively, at 22.00, 23.00, 24. 00 and 01.00 compared to saline) on the sleep electroencephalogram (EEG; recorded from 23.00 to 07.00) and nocturnal secretion of adrenocorticotrophic hormone (ACTH), cortisol, growth hormone (GH), prolactin and leptin. Repeated measures MANOVA showed that ACTH secretion during the first half of the night was reduced by the lower dose of NPY only (F = 8.7, p<0.05), while cortisol secretion during the second half of the night was reduced regardless of the dose (F = 7.9, p<0.05). Regardless of the dose, NPY enhanced sleep period time and stage 2 sleep (F = 12.8 and 5.4, each p<0.05), and also reduced sleep latency and time awake (F = 4.9 and 4.4, each p<0.05) and modulated REM sleep. In summary, NPY promotes sleep and inhibits the hypothalamo-pituitary-adrenocortical (HPA) axis in humans, pointing to a possible role of NPY agonists for the development of novel treatment strategies for affective disorders.

Prolactin-mediated gene activation in mammary epithelial cells

Mammary epithelial cells grow and develop with the onset of sexual maturity. In addition, lobular alveolar structures are formed during pregnancy, and quiescent differentiated cells secrete high levels of milk proteins after parturition. These events are governed by multiple hormones and growth factors and involve the sequential and synergistic action of functionally distinct signal transduction pathways. Milk protein genes have been analyzed and composite response elements have been identified in the promoter sequences. Transcription factors, which relay the hormonal signals, bind to these sequences. The factor that confers prolactin simulation to milk protein gene transcription has recently been identified. MGF/Stat5 is a latent transcription factor that becomes activated by a tyrosine-specific protein kinase, Jak2, associated with the prolactin receptor. Tyrosine phosphorylation converts the latent factor into one with DNA-binding and transcriptional activation potential. The regulation of MGF/Stat5 in vitro and in vivo indicates that it is a central component of the lactogenic hormone signaling pathway. Involvement of MGF/Stat5 in the signaling by other cytokines indicates that the same factor might be involved in regulation of growth-promoting genes, primarily in hematopoietic cells.

Macroprolactin; high molecular mass forms of circulating prolactin

Two high molecular mass forms of prolactin (PRL) in serum have been identified by gel filtration chromatography (GFC): macroprolactin (big-big PRL, > 100 kDa) and big PRL (40-60 kDa). Macroprolactin has a variable composition and structure, but is most frequently a complex of PRL and IgG, with a molecular mass of 150-170 kDa. It is formed in the circulation following pituitary secretion of monomeric PRL but has a longer half-life, and the PRL in the complex remains reactive to a variable extent in immunoassays. In the majority of subjects little or no macroprolactin can be detected in serum, but in some individuals it may be the predominant immunoreactive component of circulating PRL and the cause of apparent hyperprolactinaemia. Owing to its high molecular mass, macroprolactin appears to be confined to the intravascular compartment and much evidence indicates that it has minimal bioactivity in vivo and is not of pathological significance. Nevertheless, hyperprolactinaemia due to macroprolactin can lead to diagnostic confusion and unnecessary further investigation and treatment if it is not recognized as such. Macroprolactin is a common cause of apparent hyperprolactinaemia with some assays and it is essential that laboratories introduce screening programmes to examine samples with elevated total immunoreactive PRL for the presence of macroprolactin and determine the monomeric PRL component which is known to be bioactive in vivo. A number of screening tests have been described; that based on the precipitation of macroprolactin with polyethylene glycol has been the most widely validated and applied. The reference technique of GFC should be available for confirmation and further investigation of samples, giving equivocal results in screening tests. In comparison with macroprolactin, little is known about big PRL. It is a more consistent component of total serum PRL but rarely, if ever, the cause of hyperprolactinaemia. Further research is required into the nature of macroprolactin and big PRL, the relationships between high molecular mass forms of PRL, and their clinical significance.

Cocaine's effects on neuroendocrine systems: clinical and preclinical studies

This review examines the effects of cocaine on the neuroendocrine system and summarizes findings from clinical studies of cocaine abusers and preclinical studies in rodents and rhesus monkeys. The effects of acute and chronic cocaine administration on anterior pituitary, gonadal, and adrenal hormones are described, and the functional consequences of chronic cocaine exposure are discussed. Many of cocaine's acute effects on the endocrine system are consistent with its actions as a monoamine reuptake inhibitor. Acute cocaine administration stimulates release of gonadotropins, ACTH, and cortisol or corticosterone and suppresses prolactin levels. It has been difficult to detect changes in basal levels of most hormones or alterations in hormone responsiveness to a challenge dose of cocaine or other agents after chronic cocaine treatment. Interpretation of clinical data is often complicated by polydrug abuse involving opiates and alcohol as well as cocaine. However, preclinical studies of the effects of chronic cocaine exposure on integrated neuroendocrine function have revealed disruptions of the estrous cycle in rats and the menstrual cycle in rhesus monkeys. Furthermore, the menstrual cycle disorders observed in rhesus monkeys parallel those reported in women who abuse cocaine. Much remains to be learned about cocaine's interactions with the endocrine system and the consequences of cocaine abuse for reproductive function.

Time for a New Perspective on Prolactin in Metabolism

The pituitary hormone prolactin (PRL) regulates a variety of functions beyond reproduction. The association between physiological (pregnancy) and pathological (prolactinoma) hyperprolactinemia and metabolic alterations led to the concept of this hormone being diabetogenic. However, large cohort clinical studies have recently shown that low circulating PRL levels are associated with metabolic disease and represent a risk factor for type 2 diabetes (T2D), whereas high PRL levels are beneficial. Moreover, PRL acts on the pancreas, liver, adipose tissue, and hypothalamus to maintain and promote metabolic homeostasis. By integrating basic and clinical evidence, we hypothesize that upregulation of PRL levels is a mechanism to maintain metabolic homeostasis and, thus, propose that the range of PRL levels considered physiological should be expanded to higher values.

Acute carbon dioxide exposure in healthy adults: evaluation of a novel means of investigating the stress response

Acute hypercapnia was studied to assess its potential as a noninvasive and simple test for evoking neuroendocrine, cardiovascular and psychological responses to stress in man. A single breath of four concentrations of carbon dioxide (CO(2)), 5%, 25%, 35% and 50%, was administered to nine healthy volunteers in a randomized, single-blind fashion. Although no adverse effects occurred, most subjects were unable to take a full inspired vital capacity breath of 50% CO(2). In response to the remaining exposures, subjective and somatic symptoms of anxiety increased in a dose-dependent manner. Unlike 5% and 25% CO(2), 35% CO(2) stimulated significant adrenocorticotropic hormone and noradrenaline release at 2 min and cortisol and prolactin release at 15 min following inhalation. This same dose also provoked a significant bradycardia that was followed by an acute pressor response. No significant habituation of psychological, hypothalamic-pituitary-adrenal (HPA) or cardiovascular responses following 35% CO(2) was seen when this dose was repeated after 1 week. A single breath of 35% CO(2) safely and reliably produced sympathetic and HPA axis activation and should prove a useful addition to currently available laboratory tests of the human stress response.

Pharmacodynamic hormonal effects of anamorelin, a novel oral ghrelin mimetic and growth hormone secretagogue in healthy volunteers

OBJECTIVE

Activation of ghrelin receptors stimulates GH secretion and appetite, increasing lean body mass and body weight. However, clinical use of ghrelin is limited because it has a short half-life and must be administered parenterally. Anamorelin is a novel, orally active, non-peptidic ghrelin mimetic and growth hormone secretagogue. Our objective was to evaluate its hormonal effects in healthy subjects.

DESIGN

A double-blind, randomized, placebo-controlled study evaluated the short-term effects of anamorelin on GH, insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), prolactin, ACTH, LH, FSH, TSH, cortisol, insulin and glucose. Normal healthy volunteers (n=32) recruited from the general population were administered escalating doses of anamorelin (25, 50, and 75 mg daily) vs. placebo.

RESULTS

Anamorelin significantly increased GH levels at all doses (p

CONCLUSIONS

Anamorelin increases GH, IGF-1, IGFBP-3 and body weight with good tolerability and selectivity, without affecting other anterior pituitary axes or fasting glucose levels.

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MESH Headings

• Administration, Oral
• Adolescent
• Adrenocorticotropic Hormone/drug effects
• Adrenocorticotropic Hormone/metabolism
• Adult
• Blood Glucose/drug effects
• Blood Glucose/metabolism
• Body Weight/drug effects
• Double-Blind Method
• Female
• Follicle Stimulating Hormone/metabolism
• Ghrelin/analogs & derivatives
• Ghrelin/pharmacology
• Hormones/metabolism
• Human Growth Hormone/metabolism
• Humans
• Hydrocortisone/metabolism
• Insulin/metabolism
• Insulin-Like Growth Factor Binding Protein 3
• Insulin-Like Growth Factor Binding Proteins/drug effects
• Insulin-Like Growth Factor Binding Proteins/metabolism
• Male
• Placebos
• Prolactin/drug effects
• Prolactin/metabolism
• Receptor, IGF Type 1/drug effects
• Receptor, IGF Type 1/metabolism
• Thyrotropin/drug effects
• Thyrotropin/metabolism
• Young Adult

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Risperidone, but not olanzapine, decreases bone mineral density in female premenopausal schizophrenia patients

BACKGROUND

The hyperprolactinemia induced by conventional antipsychotics often leads to osteoporosis. The commonly used atypical antipsychotics risperidone and olanzapine vary in their hyperprolactinemic properties. Therefore, we compared hormone profiles and bone properties in female premenopausal schizophrenia patients treated with either risperidone or olanzapine.

METHOD

In a cross-sectional study, consecutive premenopausal, female, DSM-IV schizophrenia patients who were treated with either risperidone (N = 12) or olanzapine (N = 14) for at least 2 years were included. Dual energy X-ray absorptiometry evaluated bone mineral density, and multisite quantitative ultrasound measured bone speed of sound. In addition, profiles of urinary excretion of deoxypyridinoline and circulating levels of hormones and lipids were assessed.

RESULTS

Serum prolactin levels were higher in the risperidone-treated group as compared with the olanzapine subjects (123 +/- 144 and 25.9 +/- 25.7, p <.05). Whereas bone mineral density was similar in the treatment groups, bone speed of sound was lower in the risperidone group as compared with the olanzapine-treated group. Expressed as age-adjusted Z score, bone speed of sound at the radius was -0.31 and 0.58, respectively, p <.05, and at the phalanx, -1.41 and 0.04, respectively, p <.05. The bone speed of sound in the risperidone-treated patients inversely correlated with urinary deoxypyridinoline excretion (r = 0.73, p <.05).

CONCLUSION

Risperidone treatment, as opposed to olanzapine, for female premenopausal schizophrenia results in hyperprolactinemia and clinically relevant decrease in bone mineral density. The calculated relative risk for fragility fracture of women treated with risperidone as compared to those treated with olanzapine is 1.78 when bone speed of sound was measured at the phalanx and 1.23 when measured at the radius.

Effects of a quick-release form of bromocriptine (Ergoset) on fasting and postprandial plasma glucose, insulin, lipid, and lipoprotein concentrations in obese nondiabetic hyperinsulinemic women

OBJECTIVE

To assess the effect on various aspects of carbohydrate and lipid metabolism of administering a quick-release formulation of bromocriptine (Ergoset) to obese, nondiabetic, hyperinsulinemic women.

RESEARCH DESIGN AND METHODS

Hourly concentrations of prolactin, glucose, insulin, free fatty acid (FFA), and triglyceride were measured for 24 h before and after approximately 8 weeks of treatment with Ergoset. In addition, fasting lipid and lipoprotein concentrations and the steady-state plasma glucose (SSPG) concentration in response to a continuous infusion of somatostatin, insulin, and glucose were determined before and after Ergoset administration.

RESULTS

Circulating prolactin concentrations were dramatically decreased (P < 0.001) following treatment, associated with a significant fall (P < 0.05) in 24-h-long plasma glucose, FFA, and triglyceride concentrations. Neither circulating plasma insulin concentrations nor the ability of insulin to mediate glucose disposal changed with treatment. Finally, fasting total cholesterol fell (P < 0.05) and the ratio of total to HDL cholesterol decreased (P = 0.06) in association with Ergoset treatment.

CONCLUSIONS

The fact that significant metabolic improvement was seen in the obese nondiabetic hyperinsulinemic women studied suggests that Ergoset could be of therapeutic benefit in clinical conditions of hyperglycemia and/or dyslipidemia.

Aripiprazole in pervasive developmental disorder not otherwise specified and Asperger's disorder: a 14-week, prospective, open-label study

OBJECTIVE

The aim of this study was to determine the effectiveness and tolerability of aripiprazole for irritability in pervasive developmental disorder not otherwise specified (PDD-NOS) and Asperger's disorder.

METHOD

This is a 14-week, prospective, open-label investigation of aripiprazole in 25 children and adolescents diagnosed with PDD-NOS or Asperger's disorder. Primary outcome measures included the Clinical Global Impressions-Improvement (CGI-I) scale and the Irritability subscale of the Aberrant Behavior Checklist (ABC-I).

RESULTS

Twenty-five subjects, ages 5-17 years (mean 8.6 years) received a mean final aripiprazole dosage of 7.8 mg/day (range 2.5-15 mg/day). Full-scale intelligence quotient (IQ) scores ranged from 48 to 122 (mean 84). Twenty-two (88%) of 25 subjects were responders in regard to interfering symptoms of irritability, including aggression, self-injury, and tantrums, with a final CGI-I of 1 or 2 (very much or much improved) and a 25% or greater improvement on the ABC-I. The final mean CGI-I was 1.6 (p

CONCLUSIONS

These preliminary data suggest that aripiprazole may be effective and well tolerated for severe irritability in pediatric patients with PDD-NOS or Asperger's disorder. Larger-scale placebo-controlled studies are needed to elucidate the efficacy and tolerability of aripiprazole in this understudied population.

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MESH Headings

• Adolescent
• Antipsychotic Agents/adverse effects
• Antipsychotic Agents/therapeutic use
• Aripiprazole
• Asperger Syndrome/drug therapy
• Asperger Syndrome/physiopathology
• Body Mass Index
• Child
• Child Development Disorders, Pervasive/drug therapy
• Child Development Disorders, Pervasive/physiopathology
• Child, Preschool
• Female
• Humans
• Irritable Mood/drug effects
• Male
• Pilot Projects
• Piperazines/adverse effects
• Piperazines/therapeutic use
• Prolactin/drug effects
• Prolactin/metabolism
• Prospective Studies
• Psychiatric Status Rating Scales
• Psychometrics
• Quinolones/adverse effects
• Quinolones/therapeutic use
• Severity of Illness Index

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Grants

• K23 MH68627 NIMH NIH HHS
• K23 MH068627 NIMH NIH HHS
• K12 UL1 RR025761 NCRR NIH HHS
• R01 MH072964 NIMH NIH HHS
• UL1 RR025761 NCRR NIH HHS

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Serotonin function in human subjects: intercorrelations among central 5-HT indices and aggressiveness

Three central indices of serotonin (5-HT) system activity in human subjects were examined to: (a) estimate intercorrelations among 5-HT indices and (b) compare correlations of these indices with a measure of assaultiveness (Buss-Durkee 'Assault') in personality-disordered individuals. Cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) concentration and prolactin responses to m-chlorophenylpiperazine (m-CPP) m-CPP (PRL[m-CPP]) and fenfluramine (PRL[FEN]), served as indices of pre-, post- and 'net'-synaptic central 5-HT activity, respectively. PRL[D,L-FEN] responses were inversely related to CSF 5-HIAA concentration and positively correlated with PRL[m-CPP] responses. Both PRL[D,L-FEN] and PRL[m-CPP] response data correlated equally, and inversely, with BD Buss-Durkee Assault when the same subjects were examined. Basal CSF 5-HIAA concentration did not correlate with Buss-Durkee 'Assault'. PRL responses to challenge probes which involve activation of 5-HT post-synaptic receptors may correlate better than a basal measure of pre-synaptic 5-HT function with a tendency to assaultive behavior in non-criminally aggressive personality-disordered individuals.

Serotonin transporter promoter polymorphism is associated with attenuated prolactin response to fenfluramine

Disturbances in central serotonin (5-HT) function may have a role in impulsive aggression in patients with a wide range of psychiatric diagnoses. The underlying mechanism, however, remains unknown. There are several naturally occurring mutations in the 5-HT signaling pathway that may underlie differences in 5-HT function and responsivity to drugs that affect 5-HT functioning. In the present study, we examined the relationship between polymorphisms in the promoter region of the gene coding for the neuronal 5-HT transporter, fenfluramine-induced prolactin release, and aggressive impulsivity (as measured by Barratt Impulsivity Scale, Buss-Durkee Hostility Inventory, and Brown-Goodwin Aggression Scale scores), in a group of abstinent alcoholic patients and healthy volunteers. We report here that possession of the short variant of the 5-HT transporter promoter polymorphism was associated with a blunting of overall central 5-HT function, as measured by fenfluramine-induced prolactin release. We found no relationship between aggressive, hostile, or impulsive traits and fenfluramine-induced prolactin release or between these traits and polymorphisms in the 5-HT transporter promoter. Thus, we have shown that a 5-HT transporter promoter genotype, which has previously been associated with anxiety-based behaviors, alters an in vivo measure of central 5-HT function (fenfluramine-induced prolactin release), providing an important mechanism for linkage between a gene, physiological function, and behavior. Published 2001 Wiley-Liss, Inc.

Serotonin transporter (5-HTT) promoter genotype may influence the prolactin response to clomipramine

RATIONALE

A 44-base-pair insertion/deletion polymorphism in the promoter region of the human serotonin (5-HT) transporter (5-HTT) gene gives rise to a bi-allelic polymorphism designated long (l) and short (s). The s variant is associated with a lower expression of 5-HTT sites and a reduced efficiency of 5-HT reuptake.

OBJECTIVE

The aim of the present study was to determine whether the increase in brain 5-HT function produced by acute 5-HT reuptake blockade is influenced by the 5-HTT promoter l/s polymorphism.

METHODS

We measured the increase in plasma prolactin that follows acute administration of the tricyclic antidepressant clomipramine as an index of 5-HT neurotransmission in 14 healthy female subjects (7 with ss genotype and 7 with ll genotype) using a placebo-controlled crossover design.

RESULTS

Clomipramine-induced prolactin release was significantly greater in subjects with the ll genotype.

CONCLUSION

Our findings suggest that acute 5-HT reuptake blockade produces a greater increase in 5-HT neurotransmission in subjects with the ll genotype than in those with an ss genotype. These results are consistent with clinical data indicating that subjects with an ss genotype may have a poorer therapeutic response to selective serotonin reuptake inhibitor (SSRI) monotherapy.

Effects of ritanserin on the behavioral, neuroendocrine, and cardiovascular responses to meta-chlorophenylpiperazine in healthy human subjects

Ten healthy male subjects were administered i.v. meta-chlorophenylpiperazine (MCPP) (0.1 mg/kg) after oral ritanserin (5-10 mg), a putative 5HT1c/5HT2 (serotonin) antagonist, or placebo. Behavioral responses, cardiovascular effects, and neuroendocrine responses (cortisol, growth hormone, and prolactin) were measured serially for 4 hours after MCPP infusion. Premedication with ritanserin attenuated the MCPP-induced increases in self-rated anxiety and prolactin, and completely antagonized MCPP cortisol elevations. In contrast, ritanserin did not significantly alter growth hormone response to MCPP. These findings suggest a role for 5-HT1c/5-HT2 receptors in the endocrine and behavioral responses to the mixed serotonin agonist MCPP in humans.

A randomized double-blind 12-week study of quetiapine, risperidone or fluphenazine on sexual functioning in people with schizophrenia

Sexual dysfunction is common in people suffering from schizophrenia and is reported by patients to be a significant reason for medication nonadherence. This report contains data for 27 people with schizophrenia who participated in a randomized double-blind 12-week trial of risperidone (4 mg/day), quetiapine (400 mg/day) or fluphenazine (12.5 mg/day). At baseline and endpoint, subjects were rated on the Changes in Sexual Function Questionnaire (CSFQ), the Prolactin-Related Adverse Event Questionnaire (PRAEQ) and had prolactin levels drawn. Endpoint prolactin levels were 50.6 +/- 40.4, 24.4 +/- 18.5, and 8.2 +/- 4.4 mg/dl for risperidone (N = 12), fluphenazine (N = 9) and quetiapine (N=6), respectively (F = 7.5,df = 2, p = 0.005, controlling for sex). Orgasm quality/ability improved significantly for quetiapine as compared to fluphenazine and risperidone (F = 4.41, df = 2, p = 0.033). Seventy-eight percent of patients on fluphenazine reported sexual dysfunction whereas did only 42 and 50% of those on risperidone and quetiapine. Forty percent of quetiapine patients reported they felt better about their sexuality as compared to previous treatment, as did 55% on risperidone. Conversely, only 13% of fluphenazine subjects reported any improvement. Hormonal problems (menstrual problems, gynecomastia, galactorrhea) were predominately observed in risperidone-treated subjects. Overall, quetiapine was associated with a normalization of prolactin levels and had the greatest benefits among these drugs regarding sexual functioning.

Effect of verapamil on pharmacokinetics and pharmacodynamics of risperidone: in vivo evidence of involvement of P-glycoprotein in risperidone disposition

OBJECTIVE

A recent in vitro study has shown that risperidone is a substrate of P-glycoprotein. The aim of this study was to confirm the effects of verapamil, a P-glycoprotein inhibitor, on the pharmacokinetics of risperidone.

METHODS

Two 6-day courses of either 240 mg verapamil daily, an inhibitor of P-glycoprotein, or placebo were administered in a randomized crossover fashion with at least a 4-week washout period. Twelve male volunteers took a single oral 1-mg dose of risperidone on day 6 of both courses. Plasma concentrations of risperidone, 9-hydroxyrisperidone, and prolactin were monitored up to 24 hours after dosing.

RESULTS

Compared with placebo, verapamil treatment significantly increased the peak plasma concentration of risperidone by 1.8-fold and the area under the plasma concentration-time curve (AUC) from 0 to 24 hours of risperidone by 2.0-fold but did not alter the elimination half-life. The AUC from 0 to 24 hours of 9-hydroxyrisperidone, but not other pharmacokinetic parameters, was significantly increased during verapamil treatment. However, the AUC from 0 to 4 hours and the AUC from 0 to 8 hours of prolactin concentrations were not increased by verapamil treatment despite the pharmacokinetic alterations.

CONCLUSION

This study demonstrated that the bioavailability of risperidone was increased by verapamil, suggesting in vivo involvement of P-glycoprotein in the pharmacokinetics of risperidone.

Biological role of pituitary estrogen receptors ERalpha and ERbeta on progesterone receptor expression and action and on gonadotropin and prolactin secretion in the rat

Estrogen (E) is a key regulator of the synthesis and secretion of pituitary reproductive hormones [luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (PRL)]. Until recently, it was thought that all biological actions of E at the pituitary were manifested through a single E receptor (R). The pituitary, like many other reproductive tissues, expresses two isoforms of ER, alpha and beta, both activated by E. The relative contribution of alpha and beta forms in E regulatory actions is largely unknown. To this end, 2-week-old ovariectomized (OVX) rats were injected over 3 days with 25 microg estradiol benzoate (EB), 1.5 mg of propylpyrazole triol (PPT), a selective ERalpha agonist, 1.5 mg of the selective ERbeta agonist diarylpropionitrile (DPN) or a combination of PPT and DPN. Controls were injected with 0.2 ml oil. At 10:00 h on the day after treatment, trunk blood was collected to determine serum concentration of LH, FSH and PRL, and pituitaries were processed for RT-PCR analysis of total (A+B) progesterone receptor (PR) mRNA, immunocytochemistry of PR and incubation. Pituitaries from each of the five groups were incubated in DMEM, with or without 20 nM of the antiprogestin at the receptor ZK299, for 3 h with: 10(-8)M 17beta-estradiol, 10(-6)M PPT, 10(-6)M DPN, PPT+DPN or medium alone, respectively, to determine LH, FSH and PRL secretion, and, when challenged with two pulses of 15 min 1 h apart of 10(-8)M gonadotropin-releasing hormone (GnRH) (GnRH self-priming). EB, PPT and PPT+DPN treatments increased PR mRNA and the number and intensity of nuclei immunoreactive (IR) for PR in gonadotropes, and reduced the number of gonadectomy cells. Like E, PPT alone or in combination with DPN stimulated PRL secretion, increased basal and GnRH-stimulated LH and FSH secretion and induced GnRH self-priming in the absence of ZK299 in the incubation medium. DPN alone had only a significant E-like effect on gonadectomy cells and IR-PR, but not on GnRH self-priming. In addition, while DPN lacked an agonistic action on peripheral tissue and serum pituitary reproductive hormones concentration, EB, PPT and PPT+DPN induced similar uterine ballooning and vaginal cornification, and increased and decreased, respectively, serum concentrations of PRL and gonadotropins. Overall, these results indicate that most of these E actions on the pituitary are exerted through the ERalpha isoform. The finding that activation of ERbeta with its selective DPN agonist had an estrogenic effect on IR-PR nuclei, but not on GnRH self-priming, a characteristic ERalpha-mediated effect of E, suggests that the biological action of E at the pituitary may involve both isoforms of ER.