Clinical state, plasma levels of haloperidol and prolactin: a correlation study in chronic schizophrenia

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialized tools are used. Three tools have been proven useful to personalize drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 50 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimize treatment effects, minimize side effects and ultimately reduce the global burden of diseases, personalized drug treatment has not yet become the standard of care in psychiatry.

Possible biomarkers modulating haloperidol efficacy and/or tolerability

Haloperidol (HP) is widely used in the treatment of several forms of psychosis. Despite of its efficacy, HP use is a cause of concern for the elevated risk of adverse drug reactions. adverse drug reactions risk and HP efficacy greatly vary across subjects, indicating the involvement of several factors in HP mechanism of action. The use of biomarkers that could monitor or even predict HP treatment impact would be of extreme importance. We reviewed the elements that could potentially be used as peripheral biomarkers of HP effectiveness. Although a validated biomarker still does not exist, we underlined the several potential findings (e.g., about cytokines, HP metabolites and genotypic biomarkers) which could pave the way for future research on HP biomarkers.

Spanish consensus on the risks and detection of antipsychotic drug-related hyperprolactinaemia

INTRODUCTION

Iatrogenic hyperprolactinaemia (IHPRL) has been more frequently related to some antipsychotic drugs that provoke an intense blockade of dopamine D2 receptors. There is a wide variation in clinical practice, and perhaps some more awareness between clinicians is needed. Due to the high frequency of chronic treatment in severe mental patients, careful attention is recommended on the physical risk. IHPRL symptoms could be underestimated without routine examination.

METHODOLOGY

An intense scientific literature search was performed in order to draw up a multidisciplinary consensus, including different specialists of psychiatry, endocrinology, oncology and internal medicine, and looking for a consensus about clinical risk and detection of IHPRL following evidence-based medicine criteria levels (EBM I- IV).

RESULTS

Short-term symptoms include amenorrhea, galactorrhoea, and sexual dysfunction with decrease of libido and erectile difficulties related to hypogonadism. Medium and long-term symptoms related to oestrogens are observed, including a decrease bone mass density, hypogonadism, early menopause, some types of cancer risk increase (breast and endometrial), cardiovascular risk increase, immune system disorders, lipids, and cognitive dysfunction. Prolactin level, gonadal hormones and vitamin D should be checked in all patients receiving antipsychotics at baseline although early symptoms (amenorrhea-galactorrhoea) may not be observed due to the risk of underestimating other delayed symptoms that may appear in the medium term. Routine examination of sexual dysfunction is recommended due to possible poor patient tolerance and low compliance. Special care is required in children and adolescents, as well as patients with PRL levels >50ng/ml (moderate hyperprolactinaemia). A possible prolactinoma should be investigated in patients with PRL levels >150ng/ml, with special attention to patients with breast/endometrial cancer history. Densitometry should be prescribed for males >50 years old, amenorrhea>6 months, or early menopause to avoid fracture risk.

Prolactin, hyperprolactinaemia and antipsychotic treatment: a review and lessons for treatment of early psychosis

Hyperprolactinaemia is a common side effect of antipsychotics; markedly raised levels are less common. Higher levels of prolactin result from longer exposure to higher doses, especially with older antipsychotics or with risperidone, sulpiride or amisulpride. Galactorrhoea, gynaecomastia, menstrual abnormalities and sexual dysfunction including hypogonadism and fertility problems are consequences of raised prolactin, and in the longer-term bone demineralisation. Younger patients may be more susceptible to hyperprolactinaemia. Trial reports often fail to state the frequency of raised levels.

Hyperprolactinemia and schizophrenia: mechanisms and clinical aspects

The association between elevated prolactin levels and conventional antipsychotics is well-established. The novel antipsychotic, risperidone, has also been shown to elevate prolactin levels. Patients undergoing treatment with these medications are at high risk for developing hyperprolactinemia, which is associated with decreased bone mineral density, osteoporosis, menstrual disruptions and infertility, galactorrhea, breast cancer, cardiovascular disorders, and sexual impairment. Patients treated with conventional antipsychotics and risperidone should be routinely screened for hyperprolactinemia, and monitored for known sequelae. Optimally, patients with hyperprolactinemia secondary to antipsychotic drug treatment should be switched to a prolactin-sparing antipsychotic. This review will briefly highlight the regulation and function of prolactin secretion, discuss clinical effects of antipsychotic-induced hyperprolactinemia, and suggest a course of treatment.

The effects of antipsychotic-induced hyperprolactinaemia on the hypothalamic-pituitary-gonadal axis

Hyperprolactinaemia is commonly induced by antipsychotic medications that have dopamine-blockade as their main mechanism of action. The purpose of this study was to assess the effect of antipsychotic-induced hyperprolactinaemia on hypothalamic-pituitary-gonadal axis (HPG) function.HPG axis function was assessed in 67 consecutive outpatients who were diagnosed with schizophrenia and stabilized for a period of not less than 2 years on typical antipsychotic medication, by means of clinical history, relevant questionnaires and measurement of plasma prolactin, estradiol, progesterone, testosterone, LH, FSH, sex hormone binding globulin, and TSH levels. Normative laboratory data were used to assess whether hormone levels fell within the reference range for a normal population. There was a significant correlation between dose of medication and plasma prolactin levels for the total group (P<0.001). Prolactin levels were significantly negatively associated with sex hormone levels in females (P<0.05). Males taking antipsychotic medication had a mean prolactin level of 404.1m/IU and mean gonadotrophin and sex hormone levels that fell within normal limits. The results of this study indicate that neuroleptic-induced prolactin secretion is a dose-related side effect and, in females, the level of hyperprolactinaemia is correlated with the degree of suppression of the HPG axis. Women taking long-term prolactin-raising antipsychotic medications are likely to be hyperprolactinaemic and have an associated hypogonadal state. In males, prolactin levels remain within normal limits, but at the upper end, with no apparent disturbance of reproductive hormones.

Associations between side effects of nemonapride and plasma concentrations of the drug and prolactin

Associations between neuroleptic side effects and plasma concentrations of the drug and prolactin were investigated in 33 acutely exacerbated schizophrenic patients (16 males and 17 females) treated with a fixed dose of nemonapride (18 mg/day), a new substituted benzamide, for 3 weeks. The most frequently observed side effects during nemonapride treatment were extrapyramidal symptoms such as akathisia (69.7%), dystonia (48.5%), hypokinesia (45.5%), tremor (39.4%) and increased salivation (36.4%). There were positive correlations between prolactin response and extrapyramidal side effects (EPS) scores after 1 week (Spearman rank correlation rs=.651, P<.01), 2 weeks (rs=.567, P<.05) and 3 weeks (rs=.670, P<.01) in male patients although no significant correlations were found in female or total patients. No significant correlations were found between plasma concentrations of the drug and total or any subscale side effects scores. The present study thus suggests that the spectrum of nemonapride-induced side effects is characterized by predominant extrapyramidal symptoms, and that prolactin response as an index of dopamine blockade reflects severity of EPS at least in male patients treated with nemonapride.

Neuroendocrine response to antipsychotics: effects of drug type and gender

BACKGROUND

To study the influences of drug type and gender on the neuroendocrine response to neuroleptic treatment, we compared the endocrine actions of two neuroleptics with different receptor affinity profiles--a substituted benzamide, amisulpride, a selective D2-like dopamine antagonist; and a thioxanthene, flupenthixol, a mixed D1/D2-like antagonist also blocking serotonin, H1, and D1 receptors--on anterior pituitary hormone secretion in schizophrenic patients (DSM-III-R).

METHODS

Blood was withdrawn at 15-min intervals to assess basal secretion of prolactin, growth hormone (GH), and thyroid-stimulating hormone (TSH). Four hundred micrograms of thyrotropin-releasing hormone (TRH) was injected i.v. to investigate drug effects on TRH-stimulated secretion of prolactin, TSH, and GH.

RESULTS

Prolactin plasma levels were markedly elevated in both treatment groups. In female, but not in male patients, this elevation was significantly more pronounced under amisulpride than under flupenthixol. The prolactin response to TRH was significantly blunted by amisulpride only in male subjects. While basal TSH secretion was significantly increased by both compounds, TRH-stimulated TSH secretion was elevated only in patients treated with amisulpride. Low basal prolactin levels predicted improvement of negative symptoms in patients treated with amisulpride.

CONCLUSIONS

Amisulpride's more pronounced endocrine effects may be a reflection of its distinguished pharmacology and pharmacokinetics.

The relationship between serum concentration and therapeutic effect of haloperidol in patients with acute schizophrenia

Haloperidol is the most commonly used antipsychotic drug in the therapy of acute schizophrenia. Clinicians have been using therapeutic drug monitoring in an attempt to improve clinical application of this drug. The scale of interest in this area is emphasised by the large number of studies (about 50) concerning the serum concentration-therapeutic effect relationship (SCTER) of haloperidol, including 35 studies on patients with acute schizophrenia. However, conflicting results concerning the existence and position of a therapeutic window have emerged. This article aims to provide a comprehensive review of the study design of studies in patients with acute schizophrenia before the study data are used for decision-making. For this purpose, a reproducible system for the evaluation of studies in this special area, a so-called total study score (TSS), was developed on an empirical basis. Thus, insufficient study design was found to be a reason for negative results. On the other hand, in spite of a great variability, the majority of studies with good design provided evidence for a significant SCTER: a bisigmoidal dependence of clinical effect on haloperidol serum concentration. The therapeutic effects of haloperidol increase at low concentrations, and the concentration has a maximum effect at about 10 micrograms/L and again decreasing at higher concentrations. The data of 552 patients also fit to this model in a single scatter plot (pseudo-r2 = 0.076, p < 0.001). The position of the therapeutic window was determined at about 5.6 to 16.9 micrograms/L. Patients treated with serum concentrations within this optimal range had a significantly better response compared with outside this range (p < 0.001, Student t-test). Therefore, a quantitative synthesis of all available data by means of effect-size analysis provides a mean effect-size (g) = 0.499 +/- 0.182 (standard deviation) for the comparison of haloperidol-treatment with serum concentrations within versus outside the therapeutic window. Thus, because of this moderate positive effect, serum concentration assay of haloperidol is recommended for patients with acute schizophrenia in a therapeutic drug monitoring programme. The modalities of haloperidol therapeutic drug monitoring in clinical practice are discussed, e.g. patient selection, method and time for serum concentration measurement, influence of premedication and comedication, interpretation of results and dose adjustment. Clinical investigations into this subject should focus on covariates which are responsible for the variability of the SCTER. Serum concentration assay is advised for investigations of nonresponse to exclude patients with pseudo-drug resistance.

Prolactin monitoring of haloperidol and pimozide treatment in children with Tourette's syndrome

Neuroleptic therapy of children and adolescents with Tourette's syndrome (GTS) is associated with unpredictable outcome and adverse drug responses (i.e., extrapyramidal symptoms). Assessing the potential outcomes in GTS from a physiologic marker such as plasma prolactin concentration is important in limiting exposure and optimizing therapy. In a double-blind, placebo-controlled, double crossover comparison of pimozide and haloperidol therapy, prolactin, tic severity, and extrapyramidal symptoms were assessed at a 6-week end point. Twenty-six GTS patients (10.5 +/- 2.6 years), experienced clinical response rates of 69% on 3.4 +/- 1.6 mg pimozide and 65% on 3.5 +/- 2.2 mg/day haloperidol. Pimozide responders demonstrate elevated prolactin (26.1 +/- 11.8 ng/mL) versus pimozide nonresponders (10.5 +/- 3.8 ng/mL) (p = .05) and haloperidol treated patients (p = .05). Prolactin may be a marker for tic response to pimozide, and conversely, a potential marker for haloperidol-related incidence of extrapyramidal symptoms during haloperidol therapy.

Is there a relationship between antipsychotic blood levels and their clinical efficacy? An analysis of studies design and methodology

There are now more than 50 studies concerning neuroleptic blood levels and clinical outcome relationships. Haloperidol, the most studied, is the only antipsychotic permitting some conclusions. A number of authors suggest that the striking lack of agreement between different studies results from heterogeneity of their quality. Here, we have used a scoring system for assessing the quality of those studies. According to this system, none (0/14) of the studies having a score < 0.60 was able to show a therapeutic window, as compared to 53% (10/19) of those having a score > or = 0.60 (p = 0.002, Fisher exact test). Also, the studies able to identify the presence of a therapeutic window during haloperidol treatment were those having sample size > 20 (p = 0.06) and those whose patients were treated with fixed doses (p = 0.02). The diagnosis of schizophrenia in the studies seems not to be an exclusive condition, as compared with those also including schizophreniform and schizoaffective disorders (p = 0.12). Our qualitative analysis of haloperidol blood level publications seem to indicate that an upper limit may exist for haloperidol efficacy; values above this limit seem not to provide any supplementary clinical improvement and may even reduce therapeutic effect.

Prolactin responses to haloperidol in drug-free and treated schizophrenic patients

The prolactin response to 5 mg haloperidol i.m. was studied in 12 schizophrenic patients in a drug-free state and after a month treatment with haloperidol, as a possible index of dopamine receptor sensitivity and occupancy. Blood samples were taken at times 0, 60, 90 and 120 minutes. The increase in PRL observed in the drug-free state disappeared after drug treatment. The PRL plasma levels after treatment with 60 mg haloperidol per os were higher than the maximal PRL responses after 5 mg i.m. The increases in baseline PRL caused by the treatment correlated positively to the reduction in the BPRS score. The test was also performed in a group of 11 patients chronically treated with haloperidol during a daily dose of 60 mg, and 15 days after reduction of the dose to 30 mg. PRL increases after 5 mg haloperidol i.m. were observed only after reduction of the dose. It is suggested that the prolactin response to haloperidol is an index of the occupancy of receptors that are involved in the PRL releasing mechanisms, and could be used to verify their blockade by the neuroleptics, especially in patients that do not respond positively to drug treatment.

Relationship between extrapyramidal symptoms and serum anticholinergic levels in treated chronic schizophrenics

Serum anticholinergic levels were measured by radioreceptor assay (RRA) in schizophrenic patients treated for drug-induced Parkinsonism; 68 patients stabilized on a single neuroleptic and an anticholinergic antiparkinsonian agent (benzhexol, benztropine or procyclidine) were assessed using the extrapyramidal side effects (EPS) scale prior to each blood sampling. Serum anticholinergic levels showed a significant inverse correlation with EPS but did not appear to be dose-related in any of the three anticholinergic drug groups. Percentage binding to proteins was significantly less with benztropine than either benzhexol or procyclidine. Serum-free anticholinergic levels correlated significantly with total serum levels in the benzhexol and procyclidine groups but not in the benztropine group. At serum levels above 4.5 pmol/ml atropine equivalents, EPS was significantly less than at levels below that. We discuss the implications of this finding and suggest practical clinical applications of measurement of serum anticholinergic levels. Serum neuroleptic and serum prolactin levels did not correlate with either dose or serum level of anticholinergics.

Serum haloperidol levels and clinical response in chronic, treatment-resistant schizophrenic patients

Eleven chronic treatment-resistant schizophrenic in-patients were treated with haloperidol (HPL) or placebo with a fixed ascending dose schedule for 20 weeks. Seven patients relapsed and were withdrawn and five of these re-entered, single-blind, on known active treatment. Two weekly clinical ratings and weekly serum HPL levels were carried out throughout the study. More patients on placebo dropped out and at an earlier stage than those on active treatment but the difference was not statistically significant. Despite wide individual variations in both serum HPL levels and clinical response, these were positively correlated. HPL appeared to be of more value in the prevention of relapse than in symptom reduction. Overall, the clinical response was poor and a 'therapeutic window' could not be demonstrated either for the group as a whole or in any individual patient. There was no additional therapeutic benefit in exceeding serum HPL levels of 20 ng/ml in any of our patients. Since this serum level was achieved by daily doses of 10-40 mg HPL and the relationship between dose and serum level is linear, the use of serum HPL estimations is not likely to be of value in the routine clinical management of treatment-resistant patients.

Depot neuroleptic medication and serum levels by radioreceptor assay: prolactin concentration, electrocardiogram abnormalities and six-month outcome

Twenty-six chronic schizophrenic patients on well-established depot neuroleptic regimes with stable doses (16 on fluphenazine decanoate, 10 on flupenthixol decanoate) had serum neuroleptic levels measured by radioreceptor assay (RRA) and were followed for six months. The serum prolactin (PRL) concentration and resting electrocardiogram (ECG) were also taken at the beginning of the study period. Correlations had previously been noted between RRA measured neuroleptic levels and outcome in both acute and chronic patients on oral medication. However, in this study of depot medication no significant correlations were found between serum neuroleptic concentration, serum prolactin concentration and the clinical state or outcome. The prevalence (33%) and type of ECG abnormality observed was similar to that previously reported.

Determination of chlorpromazine in serum by radioreceptor assay and HPLC

A radioreceptor assay for chlorpromazine in serum, which is based on binding to dopamine receptors, is described. This method has been postulated to measure all active metabolites as well as the parent drug. We have compared this method with an HPLC method for chlorpromazine. Dopamine-blocking activity, measured in serum samples from schizophrenic patients receiving chlorpromazine, was 1.85-9.1 times higher than serum chlorpromazine level measured by HPLC. The correlation between the two methods was 0.75. Dopamine-blocking activity was related more closely to dose of drug and to serum prolactin level than was serum chlorpromazine level measured by HPLC.

Radio receptor assay of serum neuroleptic levels in psychiatric patients

The radioreceptor assay for the measurement of neuroleptic drugs in serum has been used to study the relationship between dose and serum level in schizophrenic patients receiving these drugs. The assay was found to be reproducible and capable of detecting neuroleptics in the sera of patients receiving a range of both oral and depot drugs, with the exception of trifluoperazine spansules. Linear correlations were obtained between daily dose and serum level for each drug both in individual patients on different doses and between patients on a stable dose. Extrapyramidal side effects were related to the serum neuroleptic level within, but not between, patients. The assay may be of use in clinical practice, including the assessment of compliance or poor response to neuroleptics.

Improved gas chromatographic-mass spectrometric assay for haloperidol utilizing ammonia chemical ionization and selected-ion monitoring

An improved method for the analysis of haloperidol in human serum, utilizing gas chromatography-ammonia chemical ionization mass spectrometry is described. A tetradeutero analogue of haloperidol is utilized as the internal standard, while a second drug, thioridazine, is added as a priming compound. The characteristic high sensitivity and selectivity of selected-ion monitoring combined with the added accuracy provided by incorporation of a labeled internal standard provide a reliable method for the quantitation of low levels of haloperidol.

Haloperidol plasma levels and clinical response in paranoid schizophrenics

The relationship between haloperidol plasma levels, plasma prolactin, and therapeutic efficacy was evaluated in 20 paranoïd schizophrenics in a fixed-dose study for 6 weeks. We found a significant intrapatient cross-correlation of therapeutic efficacy, as measured by decrease in MSS and BPRS rating scales and time-dependent haloperidol and prolactin changes, which were tested at weekly intervals. However, no significant curvilinear relationship was present between steady-state haloperidol plasma levels and MSS and BPRS improvement scores. Our data do not furnish clear-cut evidence in favor of the existence of a therapeutic window for haloperidol plasma levels in paranoïd schizophrenia.

The relationship of dopamine receptor blockade to clinical response in schizophrenic patients treated with pimozide or haloperidol

Pimozide and haloperidol were found to be equally effective in the treatment of acute schizophrenia in a double-blind clinical trial involving 22 patients. Drug plasma levels measured by radioimmunoassay (RIA) did not correlate with clinical response following either drug. Nor was there any correlation between clinical response and the dopamine receptor blocking activity of either drug as measured by radio receptor assay (RRA). Following pimozide plasma prolactin (PRL) levels correlated with clinical change, although the time courses of response of PRL and clinical response were dissimilar. There was no correlation between PRL and clinical response to haloperidol. RRA and RIA values correlated highly following pimozide but not haloperidol. Our findings lead us to conclude that the RRA technique reflects the plasma level of a drug rather than its central dopamine blocking activity. We also consider that the clinical response to antipsychotic drugs in schizophrenia may be less directly linked to dopamine receptor blockade than has previously been supposed.

Prolactin response to single and multiple doses of haloperidol in schizophrenic patients

Serum prolactin and blood levels of haloperidol were assessed in schizophrenic patients after single acute oral doses of haloperidol and during fixed dose treatment with this medication. Although significant intrapatient correlations between prolactin responses to different doses of haloperidol were found, no statistically significant interpatient relationship between haloperidol dose and prolactin response emerged. There were statistically significant relationships between steady-state plasma and red cell haloperidol levels (measured by radioreceptor or gas liquid chromatographic techniques) and serum prolactin response, but not between blood levels after the acute haloperidol dose and prolactin response.

The relationship between haloperidol blood levels and clinical responses

Haloperidol blood levels in patients were determined to elucidate the relationship between blood levels and clinical effects. Determinations of haloperidol serum were performed by radioimmunoassay and the clinical status was estimated using BPRS. The relationship between haloperidol serum levels and BPRS total score was studied in 20 chronic schizophrenics currently receiving haloperidol treatment. The results did not show positive relationship between these two. Another 11 schizophrenic patients were treated with daily doses of average 6 mg of haloperidol. The patients were classified into improved and unchanged group according to the changes of BPRS total score. All 7 cases classified into the improved group had short duration of the illness less than one year. In this group, the levels were lower initially but gradually rised in paralled with the increase of extent of recovery on BPRS. Furthermore, improvement of psychopathology by means of decrease of BPRS total score was still found after haloperidol serum levels reached a plateau. The results did not support the view that high blood concentration of haloperidol might contribute to the clinical effects, but still suggested utility of measuring blood levels in acute or subacute patients being treated with haloperidol medications.

Problem-oriented drug information: a clinical pharmacological service

The experience of a drug information centre run by clinical pharmacologists and pharmacists with expertise in literature retrieval and evaluation shows there is a need for specialised drug information services both within hospital and in outpatient care. Complex clinical situations demand judicious drug use beyond the scope of desk manual guidelines. Clinical pharmacologists can help by reviewing information from medical literature and data bases not readily available to community physicians. Clinical questions are personally answered by referenced reviews after a literature search. The answers are then kept for future use in a data bank ('Drugline').

Adverse effects of anticholinergic medication on positive schizophrenic symptoms

In a series of 36 patients with acute schizophrenia flupenthixol dosage was blindly adjusted to give a fixed level of sedation. Patients were than randomly allocated to procyclidine or placebo. The patients receiving procyclidine experienced more positive schizophrenic symptoms and less severe extrapyramidal features by comparison with placebo patients. Blood levels of prolactin and flupenthixol estimated by radioimmunoassay were not significantly changed by the addition of procyclidine. Flupenthixol dosage and levels and prolactin levels were significantly related. There was no significant association between clinical and laboratory measures, with the exception that a curvilinear (inverted U) relationship was demonstrated between flupenthixol levels and antipsychotic and extrapyramidal effects. This relationship may be due to the fact that, in a study of this design, patients resistant to the effects of neuroleptic medication are likely to be given the highest doses. The findings support earlier claims that anticholinergic medication has adverse effects on schizophrenic symptoms.

Serum prolactin response to chlorpromazine and psychopathology in schizophrenics: implications for the dopamine hypothesis

The prolactin (PRL) response to 12.5 and 25 mg of chlorpromazine (CPZ) was studied in unmedicated schizophrenic patients and normal control subjects. Both doses produced significant increases in serum PRL levels compared to saline, but the response to 25 mg CPZ was significantly greater than that to 12.5 mg. The PRL response to the 12.5 mg dose only was significantly correlated with baseline PRL levels for both males and females, suggesting that endogenous dopamine release from tuberoinfundibular neurons has a much greater effect upon the PRL response to the 12.5 mg dose of CPZ than to the 25 mg dose. Both doses of CPZ tended to show lower PRL responses in the schizophrenic females. The PRL response to the 25 mg dose was negatively correlated with ratings of severity of delusions at the time of study. The PRL response to 25 mg correlated highly with the morning serum PRL levels following treatment with CPZ 100 mg and 200 mg orally b.i.d. for 1 week at each dose. The PRL response to both doses did not predict clinical response at the end of 2 weeks of treatment with fixed dosages of CPZ. Serum PRL levels during treatment with CPZ 200 mg b.i.d. were significantly negatively correlated with ratings of hallucinations. The negative correlations between severity of delusions and hallucinations and various PRL measures suggest that increased dopaminergic activity in the tuberoinfundibular hypothalamic-pituitary axis may be associated with increased activity of subcortical and cortical dopaminergic systems.

Lateral ventricular size and drug-induced Parkinsonism

Computed Tomography (CT) was used to assess lateral ventricular size in 20 psychiatric inpatients who had participated in at least 5 weeks of a fixed dose chlorpromazine (CPZ) trial. During treatment with CPZ, eight patients had required antiparkinsonian medication for treatment of rigidity. The ventricular brain ratio (VBR) of these eight patients was greater than that of either the 12 patients who did not require antiparkinsonian medication or a similarly aged control group of neurological patients, scanned for tension or migraine headaches. On the basis of these findings it is suggested that large lateral ventricular size may be associated with increased vulnerability to develop drug-induced parkinsonism.

The relationship between prolactin levels and clinical ratings in manic patients treated with oral and intravenous test doses of haloperidol

Twelve manic patients were treated for 2 weeks with oral haloperidol; in 6 patients treatment commenced with intravenous haloperidol, and intravenous 'test' doses were given after 1, 3-5 and 14 days of oral medication. From 24 hours to 14 days baseline serum prolactin levels rose towards a plateau, as did the improvement in clinical ratings. After the first intravenous test doses of haloperidol, prolactin levels peaked at 1 hour; however, they fell to a low point at 24 hours, and no response to further test doses was seen for 3-5 days. The response tended to return at 14 days. The mechanisms underlying the changes in prolactin levels, and in clinical state, are discussed.

Flupenthixol in depression. A study of serum levels and prolactin response

The relationship between improvement in symptomatology and changes in prolactin and serum cis-flupenthixol levels has been evaluated in 16 patients with a clinical diagnosis of depression, who were treated with 1 or 2 mg of flupenthixol in a once daily morning dose. No significant differences in clinical response were noted between those on 1 and 2 mg, and side effects were few. The presentation of some side effects, in particular extrapyramidal symptoms, were related to higher serum levels and prolactin levels particularly in the early stages of the study. Improvements in depressive symptoms were unrelated to serum levels, but at day 56 of the trial were positively correlated to changes in prolactin levels. Improvements in anxiety symptoms were positively related to serum levels at day 3 but negatively related at day 56. These results are discussed in the light of possible influences of dopamine antagonism in relation to an antidepressant effect.

Prolactin increases the density of striatal dopamine receptors in normal and hypophysectomized male rats

Administration of prolactin to adult male rats, by S.C. injection, significantly increases the density of the striatal dopamine (DA) receptors, without altering the apparent affinity of the receptors for [3H]spiroperidol. Larger doses of prolactin are required to increase the density of the striatal DA receptors in hypophysectomized rats compared to normal rats. These results suggest that prolactin might be the common mediator of the increase in striatal DA receptor density produced by either estrogen or haloperidol administration. Monitoring and/or altering prolactin levels might be informative in neurologic or psychiatric disorders involving striatal DA neurotransmission.

Antiemetic effect of haloperidol in the dog as related to plasma level and dose

A positive and highly significant correlation was found between SC dose, plasma concentration, and antiemetic effect of haloperidol in the dog. To protect dogs from apomorphine-induced emesis, a concentration of 1 ng haloperidol/ml plasma was always sufficient, whereas protection from emesis was never obtained with plasma levels lower than 0.53 ng/ml. The elimination rate of haloperidol from plasma varied from 1.53 to 2.60 among different animals. Thus, the interindividual variability to haloperidol was surprisingly low. Antiemetic effect and plasma elimination of haloperidol were not related to body weight.