Effectiveness of the selective D4 antagonist sonepiprazole in schizophrenia: a placebo-controlled trial

BACKGROUND

Selective localization of dopamine D(4) receptors in the prefrontal cortex and preferential affinity of clozapine for the dopamine D(4) receptor over the D(2) receptor led to the hypothesis that the superior efficacy of clozapine may be mediated via blockade of the D(4) receptor. This hypothesis was tested by evaluating sonepiprazole, a selective D(4) dopamine antagonist, in schizophrenia patients.

METHODS

We treated 467 hospitalized schizophrenia patients with scores of > or = 60 on the Positive and Negative Syndrome Scale (PANSS) with sonepiprazole, olanzapine, or placebo once daily for 6 weeks. The primary efficacy end point was the mean change from baseline in the PANSS total score at 6 weeks. Secondary efficacy end points were the mean change from baseline in the PANSS factor scores, the Brief Psychiatric Rating Scale score, the Clinical Global Impressions Severity of Illness score, and the Calgary Depression Scale score.

RESULTS

No statistically significant differences were observed between placebo and any sonepiprazole dose on the primary or any secondary end point after 6 weeks of treatment. Statistically significant differences, favoring olanzapine over placebo, were observed on all efficacy end points but the Calgary Depression Scale.

CONCLUSIONS

Sonepiprazole was ineffective for the treatment of patients with schizophrenia.

TSH circadian secretions in aged men and effect of phosphatidylserine treatment

In 20 euthyroid aged men (from 65 to 85 years of age) no significant circadian periodicity of thyrotropin (TSH) secretion has been shown by the population mean cosinor method. At the end of a period of 30 days of hospitalization the cosinor evaluation of TSH secretion showed a restored highly significant (p less than 0.001) circadian rhythmicity in phosphatidylserine (PS) (400 mg/daily) treated group (10 aged subjects). By contrast, hospitalization seems to further deteriorate the periodicity of the hormone secretion in 10 placebo-treated subjects.

Luteinizing hormone pulsatile secretion and pituitary response to gonadotropin releasing hormone and to thyrotropin releasing hormone in male epileptic subjects on chronic phenobarbital treatment

Endocrine changes have been reported in treated epileptic subjects, who often exhibit sexual dysfunctions, but the endocrine effects of single antiepileptic drugs have not been completely elucidated. In this study we have investigated the influence of phenobarbital (PB) on adenopituitary function and on peripheral sexual steroid pattern in 8 epileptic males. Chronic PB treatment does not modify luteinizing hormone (LH) pulsatile secretion. In the same subjects, LH and follicle stimulating hormone (FSH) response to Gonadotropin Releasing Hormone was blunted with respect to healthy controls both in terms of absolute values and of secretion areas. No difference was found in prolactin (PRL) response to Thyrotropin Releasing Hormone. In the epileptic group a significant increase in the levels of sex hormone binding globulin and a consequent decrease of the percent free testosterone have been observed. PB treatment also significantly lowers 17-beta-estradiol mean levels. These data suggest that PB independently affects both gonadotropin secretion and peripheral steroid pattern.

Prolactin secretion in epileptic subjects treated with phenobarbital: sex differences and circadian periodicity

Circulating basal prolactin (PRL) levels were evaluated in 126 subjects of both sexes with partial or generalized epilepsy, who were treated with phenobarbital (PB) alone or in combination with either phenytoin or benzodiazepines. A significant increase in PRL levels was observed in male, but not in female, patients compared with a sex- and age-matched healthy volunteer group. Circadian PRL secretion, studied in six male epileptic patients on PB monotherapy and in nine normal subjects, showed comparable 24-h PRL mean values and a preserved PRL surge during the night in both groups; however, a statistically significant additional peak was found in male epileptic subjects during the late afternoon. The cosinor analysis of the data, used to evaluate PRL rhythmicity, showed a disruption of the 24-h periodicity in epileptic subjects, while the 12-h periodicity was maintained. These results indicate that central and/or peripheral mechanisms involved in PRL secretion control are more sensitive to PB alone or in combination with other antiepileptic drugs in male than in female subjects. However, the changes of PRL secretion we found were small and unrelated to the different clinical conditions.

Changes in the dopaminergic control of prolactin secretion and in ovarian steroids in migraine

Prolactin (PRL) responses to dopamine (DA) blockers and to direct and indirect DA agonists have been studied in 23 healthy women, 17 women with catamenial migraine and 17 with non-catamenial migraine in both their follicular and luteal phases. PRL responses to the DA blockers were greater in the follicular phase of both migraine groups than in controls. The inhibitory effect of nomifensine on PRL secretion was dampened in the follicular phase of both migraine groups. These findings demonstrate an increased PRL reserve in migraine and suggest the existence of a dopaminergic supersensitivity of the lactotrophic postsynaptic DA receptors. The impaired inhibitory effect of nomifensine on PRL secretion hints at a decrease of the presynaptic DA content in tuberoinfundibular DA neurons. In migrainous women 17-beta-oestradiol levels are higher in both ovarian phases, whereas progesterone concentrations and the progesterone to oestradiol ratio are lower than in healthy subjects in the luteal phase. These data suggest the existence of a change in the oestrogen-dependent modulation of pituitary DA receptors.

Benserazide effects on growth hormone, prolactin, and thyrotropin in normal and acromegalic man

The effect of benserazide administration on the secretion of GH, PRL, and TSH has been considered as an index of dopamine regulatory actions. Nine acromegalic patients and nine normal subjects were given a single 125 mg oral dose of benserazide, and serum GH, PRL, and TSH were determined by RIA methods every 30 min for 4 h. Benserazide did not alter GH values either in normal subjects or in acromegalic patients. A significant increase of serum PRL was found in both groups, and the increase was similar in normoprolactinemic and in hyperprolactinemic acromegalic patients. A significant increase in TSH levels was found only in acromegalic patients. Thus, a decrease in dopamine outside the blood-brain barrier did not affect GH secretion, whereas PRL secretion was changed in the acromegalic as well as in the control group.

Effects of carbamazepine on prolactin secretion in normal subjects and in epileptic subjects

The effects of carbamazepine (CBZ) on spontaneous secretion of prolactin (PRL) and after stimulation with thyrotropin releasing hormone (TRH) were evaluated. Volunteer subjects after acute CBZ administration, and epileptic subjects with complex partial seizures chronically treated with CBZ, were examined. In an epileptic group, CBZ did not change TRH stimulatory effect on PRL secretion. No appreciable changes of PRL spontaneous secretion were observed, and only a small increase of sleep-entrained values with preservation of the normal secretory circadian rhythm was noted, both in normal subjects and in epileptic subjects. This result could be explained by a serotoninergic activity of PRL changes produced by CBZ in these various conditions agrees with the absence of published reports of CBZ side effects associated with hyperprolactinemia.

Effects of a single oral dose of phenobarbital on prolactin, growth hormone and luteinizing hormone in normal women

The effects of a single oral dose of phenobarbital (PB) on the 24 h secretion of prolactin, growth hormone and luteinizing hormone have been evaluated in normal women. An EEG record was taken and barbiturate levels assayed in serum. A statistically significant decrease of growth hormone 24 h mean levels was observed and growth hormone and prolactin values during sleep were diminished. No changes in luteinizing hormone concentrations were observed. After PB the EEG showed no important alterations in sleep pattern, but on the power analysis an increase above 16 Hz absolute power was detected during the waking period.