Metabolic consequences of atypical antipsychotic drugs

Atypical antipsychotic drugs have become the treatment of choice for psychotic disorders. However, these medications, though certainly superior in many respects to the more traditional medications, have been shown to have a number of untoward consequences. Understanding of the metabolic consequences of these medications is essential for the psychiatrist. The possible development of diabetes, weight gain, and hypertriglyceridemia in patients taking atypical antipsychotics makes it imperative that the prescribing physician regularly monitor patients on these agents. One possible monitoring scheme is outlined and recommendations for treatment are discussed.

Effect of loxapine on peripheral dopamine-like and serotonin receptors in patients with schizophrenia

OBJECTIVE

To investigate the effect of loxapine on peripheral dopamine D2-like and serotonin receptor binding and on psychotic symptoms.

PATIENTS

Patients (n = 24) meeting the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, for schizophrenia were selected from an outpatient clinic (age range 18-70 yr).

METHODS

Patients were given loxapine (dose determined by a physician) for a period of 12 weeks. There were clinic visits at before treatment began and at 6 weeks and 12 weeks of treatment. Scores on a variety of efficacy and safety scales were recorded at each visit, and blood was drawn for receptor assays.

RESULTS

Patients showed significant improvement on most psychiatric assessment scales after 6 and 12 weeks of treatment with loxapine, and both lymphocyte D2-like and 5-HTL2A platelet receptor binding were down-regulated after 6 and 12 weeks. The degree of receptor down-regulation was not significantly correlated with improvements in psychotic symptoms, however.

CONCLUSION

Loxapine down-regulated both lymphocyte D2-like and platelet 5-HT2A receptors to the same extent, suggesting that both receptors are involved in the mechanism of action of loxapine in patients with schizophrenia.

Classification and treatment of tardive syndromes

BACKGROUND

Tardive syndromes are a group of delayed-onset abnormal involuntary movement disorders induced by a dopamine receptor blocking agent. There are several phenomenologically distinct types of TS.

REVIEW SUMMARY

The term tardive dyskinesia has been used to refer to the TS that presents with rapid, repetitive, stereotypic movements mostly involving the oral, buccal, and lingual areas. Tardive dystonia can be focal, segmental, or generalized. It commonly affects the face and neck followed by the arms and trunk. It usually results in retrocollis when it involves the neck and trunk arching backwards when it involves the trunk. Tardive akathisia is characterized by a feeling of inner restlessness and jitteriness with an inability to sit or stand still. Other tardive syndromes include tardive tics, myoclonus, tremor, and withdrawal-emergent syndrome. It remains unclear whether tardive parkinsonism truly exists. The only way to prevent TS is to avoid its etiologic agents. Chronic use of dopamine receptor blocking agents should be limited as much as possible to patients with chronic psychoses. In general, for mild TS, reducing the neuroleptic dose, switching to an atypical agent, or discontinuing antipsychotic treatment altogether in the hope of facilitating remission is recommended. For moderate to severe TS, tetrabenazine or reserpine may be the most effective agent. Neuroleptics should be resumed to treat TD in the absence of active psychosis only as a last resort for persistent, disabling, and treatment-resistant TD.

CONCLUSIONS

The severity of the TS and the absolute need for antipsychotic therapy often dictate the treatment approach for this disorder.

Erythromycin accelerates gastric emptying in a dose-response manner in healthy subjects

STUDY OBJECTIVES

To evaluate whether a dose-response curve exists for erythromycin, determine the lowest effective dose of erythromycin needed to improve gastric motility, and compare erythromycin's effectiveness with that of metoclopramide in improving gastric emptying.

DESIGN

Randomized, crossover, multiintervention trial.

SETTING

Inpatient clinical research center.

SUBJECTS

Ten healthy volunteers (four men, six women) from the general population.

INTERVENTION

On each study day, the subjects were infused with erythromycin 0.75 mg/kg, 1.5 mg/kg, or 3.0 mg/kg; metoclopramide 10 mg; or placebo, in random order. Subjects then drank Ensure 200 ml mixed with acetaminophen 1.5 g. Gastric emptying was estimated by comparing the area under the curve after 60 minutes for acetaminophen absorption using four timed blood draws.

MEASUREMENTS AND MAIN RESULTS

Erythromycin increased gastric emptying in a dose-response manner. Erythromycin 3.0 mg/kg and metoclopramide 10 mg were associated with statistically significant increases in liquid gastric emptying compared with placebo. During infusion, nausea and stomach cramping were associated with the 3.0-mg/kg dose of erythromycin; drowsiness was associated with metoclopramide.

CONCLUSION

In patients requiring intravenous erythromycin for gastric motility, the 3.0-mg/kg dose seems the most effective, with a reasonable side effect profile.

Antipsychotic drugs and QT interval prolongation

The QTc prolongation by antipsychotic drugs is of major concern, especially in light of the data indicating an increased risk of sudden death in psychiatric patients taking these drugs. Sudden death in psychiatric patients could be partially attributed to drug-induced torsades de pointes and for this reason careful evaluation of QTc prolonging properties of antipsychotic drugs is needed. Antipsychotic drugs prolong QT interval usually by blocking the potassium IKr current. Improved understanding of ion channel structure and kinetics and its role in repolarization has tremendous impact on understanding of the mechanisms of drug-induced QT prolongation and torsades de pointes. Proarrhythmia caused by a QT-prolonging drug occurs infrequently, and usually multiple factors need to operate to precipitate such an event including a combination of two or more drugs affecting the same pathway, hypokalemia, and possibly genetic predisposition. Currently prescribed antipsychotics might cause QT prolongation ranging from 4-6 ms for haloperidol and olanzapine to 35 ms for thioridazine. The response of a patient to a drug is very individual and therefore an individualized system of drug administration and monitoring needs to be developed which takes into account baseline QTc duration and its changes after a drug was introduced. A systematic approach while stratifying psychiatric patients as those with short QTc (QTc < or = 0.41 sec), borderline QTc (QTC = 0.42-0.44 sec), and prolonged QTc (0.45 sec) is being proposed to improve the safety of administering antipsychotic drugs and to decrease the risk of drug-related sudden death in psychiatric patients.

Acute massive pulmonary thromboembolism associated with risperidone and conventional phenothiazines

To assess the contribution of antipsychotic medication in Japanese patients suffering acute massive pulmonary thromboembolism, records of patients with idiopathic pulmonary thromboembolism associated with antipsychotic medication who were seen in a Japanese Emergency Center from January 1996 to December 2000 were reviewed. Age, gender, physical status, clinical presentation, antiphospholipid antibody, outcome, psychiatric profile, and antipsychotic medication use were examined. Seven patients had acute pulmonary thromboembolism associated with antipsychotic drug use, representing 44% of all patients with idiopathic pulmonary thromboembolism. The 7 patients developed symptoms in the early morning. More women than men were affected. In 5 cases, chlorpromazine and other phenothiazines had been prescribed, whereas in 2 cases, risperidone, a mixed serotonin 5HT(2A) and dopamine D(2) receptor antagonist, had been taken for 40 days and 6 days, respectively. In 4 cases, including the patients taking risperidone, antiphospholipid antibodies were not present. Although statistically significant conclusions can not be drawn from this study, the data suggest that patients receiving risperidone, as well as conventional phenothiazines, are at risk for acute pulmonary thromboembolism, even if otherwise healthy. Strong affinity for the 5HT(2A) receptor of the novel antipsychotic may increase coagulability and the risk of thromboembolism.

Neuroleptic malignant syndrome: uncommon postoperative diagnostic dilemma

Neuroleptic malignant syndrome occurred in a 71-year-old man on haloperidol therapy for mild depressive dementia. After coronary artery bypass grafting, he developed hyperthermia, elevated creatine kinase without a corresponding rise in the MB-isoenzyme, leukocytosis, raised liver enzymes, urea, and creatinine. His condition responded to bromocriptine therapy.

Dopamine antagonists and the development of breast cancer

BACKGROUND

Although animal studies have raised the possibility that prolactin-elevating dopamine antagonists used to treat psychotic disorders may initiate and promote breast cancers, epidemiologic studies in humans have been limited and inconsistent.

METHODS

A retrospective cohort study was conducted of 52 819 women exposed and 55 289 not exposed to dopamine antagonists between January 1, 1989, and June 30, 1995. All participants were 20 years or older, initially free of breast cancer, and enrolled in the Medicaid or the Pharmaceutical Assistance to the Aged and Disabled programs of New Jersey. Incident breast cancer cases were identified through the New Jersey Cancer Registry and definitive breast cancer surgeries. Adjusted hazard ratios of breast cancer were calculated from multivariable proportional hazards models.

RESULTS

Use of antipsychotic dopamine antagonists was associated with a 16% increase in the risk of breast cancer (adjusted hazard ratio, 1.16; 95% confidence interval, 1.07-1.26), with a dose-response relationship between larger cumulative dosages and greater risk. The increased risk was also seen in women who used prolactin-elevating antiemetic dopamine antagonists despite having different breast cancer risk profiles than antipsychotic dopamine antagonist users. Dopamine antagonist use was not associated with risk of colon cancer, a control condition not related to elevated prolactin levels. The increased risk of breast cancer among dopamine antagonist users was not explained by increased surveillance or protopathic bias.

CONCLUSIONS

Antipsychotic dopamine antagonist use may confer a small but significant risk of breast cancer. In light of the small hazards and the possibility of residual confounding, these findings should lead to follow-up investigations but not to changes in treatment strategies.

Dopamine D3 receptor antagonism inhibits cocaine-seeking and cocaine-enhanced brain reward in rats

dopamine D3 receptor is preferentially localized to the mesocorticolimbic dopaminergic system and has been hypothesized to play a role in cocaine addiction. To study the involvement of the D3 receptor in brain mechanisms and behaviors commonly assumed to be involved in the addicting properties of cocaine, the potent and selective D3 receptor antagonist trans-N-[4-[2-(6-cyano-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl] cyclohexyl]-4-quinolininecarboxamide (SB-277011-A) was administered to laboratory rats, and the following measures were assessed: (1) cocaine-enhanced electrical brain-stimulation reward, (2) cocaine-induced conditioned place preference, and (3) cocaine-triggered reinstatement of cocaine seeking behavior. Systemic injections of SB-277011-A were found to (1) block enhancement of electrical brain stimulation reward by cocaine, (2) dose-dependently attenuate cocaine-induced conditioned place preference, and (3) dose-dependently attenuate cocaine-triggered reinstatement of cocaine seeking behavior. Thus, D3 receptor blockade attenuates both the rewarding effects of cocaine and cocaine-induced drug-seeking behavior. These data suggest an important role for D3 receptors in mediating the addictive properties of cocaine and suggest that blockade of dopamine D3 receptors may constitute a new and useful target for prospective pharmacotherapies for cocaine addiction.

Efficacy and tolerability of prochlorperazine buccal tablets in treatment of acute migraine

OBJECTIVES

To study the efficacy and tolerability of prochlorperazine (PCZ) management of acute migraine.

DESIGN AND METHODS

A double blind comparative study was conducted to assess the efficacy of buccal PCZ 3 mg compared with oral ergotamine tartarate 1 mg plus caffeine 100 mg (ERG) or placebo (buccal or oral) for treatment of acute migraine. In all, 114 episodes of acute migraine were evaluated. Patients graded symptoms on a four-point scale before and up to 4 hours after treatment. The primary efficacy parameters included headache resolution within 2 hours (grade 3 or 2 to grade 0) and alleviation of other accompanying symptoms of migraine. The supplementary endpoints included improvement in quality of life (QOL).

RESULTS

The percentage of patients reporting resolution of headache (to grade 0) was 51.4% for buccal PCZ and 21.7% for buccal placebo, 23.1% for oral ERG and 28.6% for oral placebo, headache tended to recur in both the placebo and ERG groups after initial improvement. Buccal PCZ was well tolerated; no signs of local irritation were evident, and patients found the formulation easy to use. Mild but transient sedation and drowsiness were observed in 41%.

CONCLUSIONS

In the present study, PCZ 3 mg via the buccal route produced faster improvement and greater efficacy than placebo (oral as well as buccal) or oral ERG. The global QOL score 2 hours after treatment scores was higher in the PCZ group. Buccal PCZ may represent a particularly effective alternative for acute migraine treatment.

Comparing the side effect profile of the atypical antipsychotics

Typical antipsychotics exert their effect by blocking post-synaptic dopaminergic receptors; blockade of the mesolimbic and mesocortical pathways are therapeutic and help reduce positive psychotic symptoms but blockade of the nigro-striatal pathway produces extrapyramidal side effects (EPSE). Post clozapine, the Food and Drug Administration (FDA) has approved the use of four newer atypical antipsychotics; risperidone, olanzapine, quetiapine and ziprasidone for the treatment of schizophrenia. Because of their dual serotonin and dopamine receptor blocking abilities, atypical antipsychotics have greater efficacy (especially for negative symptoms) and fewer EPSE when compared to the typical antipsychotics. Given the lack of studies directly comparing these agents, we used the Physician Desk Reference (PDR) to calculate the treatment emergent placebo adjusted side effects for these atypical antipsychotics. The results are then presented in an easy to read table. To the best of our knowledge, this is the first comparison study involving these four newer antipsychotic agents.

Prediction and assessment of extrapyramidal side effects induced by risperidone based on dopamine D(2) receptor occupancy

In the present study, we attempted to predict the risk of extrapyramidal side effects of a selective monoaminergic antagonist, risperidone, by analyzing the correlation between the dopamine D(2) receptor occupancy and the degree of extrapyramidal side effects of the drug. The occupancies of D(2) and 5-HT(2) receptors at various doses of risperidone were calculated by means of a receptor occupancy theory. The extrapyramidal side effects after administration of risperidone were attempted to predict by theoretical analysis of the correlation between the calculated occupancies and the evidence of extrapyramidal symptoms using a ternary complex model. The pharmacokinetic/pharmacodynamic analysis utilized the data concerning the pharmacokinetics of risperidone and 9-hydroxyrisperidone (active metabolite), their binding affinities with D(2) and 5-HT(2) receptors, and the clinical evidence of extrapyramidal symptoms (Extrapyramidal Symptom Rating Scale: ESRS), gathered from the literature. The mean occupancy of 5-HT(2) receptors after the administration of regular doses of risperidone was suggested to be more than 90%, whereas the mean occupancy of D(2) receptors varied between 50-80%, depending on the dose. The correlation between the occupancy of D(2) receptors and the extrapyramidal symptoms could be successfully analyzed with a ternary complex model, showing the predictability of the model for the extrapyramidal side effects of risperidone. Since the estimated risk of the extrapyramidal side effects varied with the dose, the present method of predicting the extrapyramidal side effects of risperidone may provide a basis for developing a rational dosing regimen for the drug.

Comprehensive understanding of schizophrenia and its treatment

An overview of schizophrenia is presented, including diagnostic criteria, etiology, neurologic findings, pharmacotherapy options, quality-of-life issues, and the financial impact of the disease. Schizophrenia is a chronic disease characterized by positive symptoms, negative symptoms, mood symptoms, and cognitive deficits. Often comorbid substance abuse is present. Schizophrenia accounts for 20% of all hospital bed-days and over 50% of all psychiatric beds in the United States. There is a strong genetic component to schizophrenia, and other possible contributing factors are explored. The diagnostic workup should include a detailed longitudinal history, mental status exam, physical and neurologic exams, and laboratory tests. A magnetic resonance imaging scan can rule out structural causes of psychosis and should be considered at the time of diagnosis. Treatment is based on a biopsychosocial model including pharmacotherapy in combination with individual, group, and family therapies. Rather than classifying antipsychotics as typical or atypical, a new classification scheme has been proposed based on risk of causing extrapyramidal symptoms and tardive dyskinesia (TD), effect on prolactin level, and efficacy profile: first-generation or traditional agents (e.g., chlorpromazine and haloperidol); second-generation agents (e.g., risperidone and ziprasidone); and third-generation agents (e.g., clozapine, olanzapine, and quetiapine). The binding affinities of antipsychotics in the brain help explain the mechanisms by which different antipsychotics alleviate specific symptoms of schizophrenia, as well as cause specific adverse effects. Improved cognition, fewer depressive and mood symptoms, and decreased risk of TD associated with third-generation antipsychotics have improved the quality of life for patients with schizophrenia.

Differences in the effects of haloperidol and clozapine on brain serotonin and dopamine metabolism and on tests related to extrapyramidal functions in rats

BACKGROUND

An important goal of current neuroleptic research is to develop antipsychotic compounds with a low incidence of extrapyramidal side effects (EPS). Clozapine, the first of the atypical antipsychotics to be proven effective in treatment-resistant schizophrenia, is reported to produce less EPS than typical neuroleptics, such as haloperidol.

MATERIAL/METHODS

The present study compares the neurochemical profiles of clozapine and haloperidol in rats. Animals injected (i.p.) with haloperidol or clozapine were sacrificed 1h later to collect brain samples. Neurochemical estimations were carried out by HPLC-EC.

RESULTS

Administration of haloperidol at doses of 1.0, 2.5 and 5.0 mg/kg increased the concentration of homovanillic acid (HVA), a metabolite of dopamine (DA), in the striatum and rest of the brain. Clozapine-injected rats (2.5, 5.0 and 10.0 mg/kg) showed smaller increases in the striatum, but not in the rest of the brain. Dihydroxyphenylacetic acid (DOPAC), another DA metabolite not affected by haloperidol, increased in the striatum and decreased in the rest of the brain of clozapine-injected rats. 5-Hydroxyindoleacetic acid, the predominant metabolite of serotonin, increased with haloperidol and decreased with clozapine. A high dose of haloperidol (5.0 mg/kg) increased DA and 5-HT, while an equivalent does of clozapine (10.0 mg/kg) decreased levels in the rest of the brain. The effects of both drugs on the HVA/5-HIAA and DOPAC/5-HIAA ratios were also different.

CONCLUSIONS

The differing activities of the two drugs at DA and serotonin receptors implies an important role for serotonin in treatment-resistant schizophrenia and a lower incidence of EPS.

Cardiac arrest after intravenous metoclopramide - a case of five repeated injections of metoclopramide causing five episodes of cardiac arrest

We describe a patient where intravenous injection of metoclopramide was immediately followed by asystole repeatedly. The patient received metoclopramide 10 mg i.v. five times during 48 h. After interviewing the attending nurses and reviewing the written documentation, it is clear that every administration of metoclopramide was immediately (within s) followed by asystole. The asystole lasted 15-30 s on four occasions, on one occasion it lasted 2 min. The patient received atropine 0.5-1 mg and chest compressions, before sinus rhythm again took over. We interpret this as episodes of cardiac arrest caused by metoclopramide. The rapid injection via the central venous route and the concomitant tapering of dopamine infusion might have contributed in precipitating the adverse drug reaction.

Torsadegenic action of the antipsychotic drug sulpiride assessed using in vivo canine models

A patient had QT prolongation and syncope after starting sulpiride therapy. The present experiments were performed to clarify the causal link among the sulpiride administration, QT prolongation, and the onset of torsade de pointes. Two in vivo models were used: halothane-anesthetized dogs and chronic atrioventricular (AV) block dogs. In the halothane-anesthetized animals (n = 6), sulpiride (2 and 20 mg/kg intravenously) decreased total peripheral resistance and increased heart rate, cardiac output, and ventricular contractility concomitantly. A transient attenuation of these effects occurred soon after the high-dose administration. No significant change was detected in left ventricle preload and depolarization, but repolarization and effective refractory period were significantly prolonged after high-dose administration. The extent of changes was greater in repolarization than in refractoriness, indicating prolongation of the final repolarization phase (electrically vulnerable period). In the chronic AV block animals (n = 4), onset of torsades de pointes with marked QT prolongation was demonstrated after the administration of 60 and 120 mg/kg orally of sulpiride. These results suggest that the QT prolongation and the change in the final repolarization phase with increased sympathetic tone may be the mechanisms responsible for the arrhythmogenic effect of sulpiride. Thus, caution should be paid with the use of sulpiride in patients at risk for elevated plasma concentrations and having preexisting susceptibility to QT prolongation.

Metoclopramide for nausea and vomiting of pregnancy: a prospective multicenter international study

Nausea and vomiting are very common during pregnancy, mainly throughout the first trimester. Metoclopramide is a dopamine receptor blocking drug that is commonly used to treat nausea and vomiting. The aim of this prospective study was to investigate the effect on the fetus of intrauterine exposure to metoclopramide. One hundred and seventy-five women who received metoclopramide and consulted 6 teratogen information centers in Israel, Italy, Brazil, and Canada were studied. Women exposed to metoclopramide were paired for age, smoking and alcohol consumption habits with women exposed to nonteratogens. Women in the metoclopramide group had a significantly higher rate of premature births (8.1%) as compared with the control group (2.4%) ( p = 0.02, relative risk = 3.37, 95% confidence interval 1.12-10.12). Rates of major malformations in the metoclopramide group (4.4%) did not differ from controls (4.8%) ( p = 0.84, relative risk = 0.91, 95% confidence interval 0.34-2.45). According to our findings, metoclopramide use during the first trimester of pregnancy does not appear to be associated with an increased risk of malformations, spontaneous abortions, or decreased birth weight, however, larger studies are needed to confirm these observations.

Meige syndrome with apraxia of lid opening after the discontinuation of sulpiride treatment

We report a case of Meige syndrome with apraxia of lid opening that lasted for about seven months after discontinuation of sulpiride treatment. To our knowledge, this is the first report demonstrating that Meige syndrome with apraxia of lid opening is induced by sulpiride, and that the condition persists.

Pathogenesis of degenerative retinopathies induced by thioridazine and other antipsychotics: a dopamine hypothesis

Thioridazine and other antipsychotics (neuroleptics, dopaminergic antagonists) can cause degenerative retinopathies with histological, electrophysiological and symptomatological features similar to those of primary retinitis pigmentosa. It was formerly suggested that these retinopathies are due to drug absorption by melanin of the eye which damages the choriocapillaris first and subsequently the photoreceptors and the retinal pigment epithelium. An alternative explanation of the still unclear mechanisms involved in the pathogenesis of thioridazine and other phenothiazines retinopathies has underlined the role of the drug effects on the activity of some retinal enzymatic systems which can lead to retinal dystrophy. More recent data on the complex role of dopamine (DA) and of its receptor subtypes in the retina has provided evidence that the D2 family of DA receptors, in particular the D4 receptor, is involved in the control of the synthesis of melatonin, a factor that has been shown to regulate several aspects of retinal physiology and to increase photoreceptor susceptibility to be damaged by light. Based on this knowledge, as well as on clinical data and on pharmacological considerations concerning the differences recently shown to exist among the various antipsychotics as regards their affinity for the DA receptor subtypes, we hypothesize that neuroleptic induced blockade of retinal D2/D4 receptors is among the initial events of these drug-induced degenerative retinopathies. Clinicians should be aware of the retinotoxic effects not only of thioridazine and some others phenothiazines, but also of those possibly caused by other typical and atypical antipsychotics. By evaluating the retinal status and function before and during the treatment of psychiatric patients, it should be possible to choose more accurately the safest drugs, particularly when treating predisposed subjects.

Neuronal basis of neuroleptic-induced extrapyramidal side effects

The article reviews presently commonly accepted concepts of neuronal basis of neuroleptic-induced extrapyramidal side effects. The data obtained both, in humans and laboratory animals, point to the blockade of a large number of the striatal dopamine D2 receptors by neuroleptics as a primary cause of these disturbances. This phenomenon leads to the appearance of parkinsonian symptoms shortly after therapy commencement. On the other hand, chronic administration of neuroleptics evokes supersensitivity to dopamine connected with the increased number of D2 receptors and supersensitivity of D1 receptors, which can be significant for the development of tardive dyskinesia. Primary and secondary changes in the function of dopamine receptors lead to partially opposite, pathological changes in the activity of neuronal pathways connecting the basal ganglia. Besides functional changes, neuroleptic-induced lesions of the striatal neurons and genetic predispositions can also play a role in tardive dyskinesia.

Selective disruption of the recognition of facial expressions of anger

Appetitive aggression occurs in the context of resource/dominance disputes in a wide variety of species. Hence, the possibility arises that a specific neural system may have evolved to detect and coordinate responses to this specific form of challenge or threat. The dopamine system has been implicated in the processing of signals of aggression in social-agonistic encounters in several species. Here we report that dopaminergic antagonism in healthy male volunteers, following acute administration of the dopamine D2-class receptor antagonist sulpiride, leads to a selective disruption in the recognition of facial expressions of anger (signals of appetitive aggression in humans), but leaves intact recognition of other emotions and the matching of unfamiliar faces.

Evidence-based view of safety and effectiveness of pharmacologic therapy for nausea and vomiting of pregnancy (NVP)

OBJECTIVE

Our goal was to review the safety and effectiveness of available antiemetics for treatment of nausea and vomiting of pregnancy.

STUDY DESIGN

We performed a quantitative and qualitative overview of observational controlled studies for drug safety in pregnancy and randomized controlled trials for drug effectiveness for nausea and vomiting in pregnancy.

RESULTS

All of the following are safe and effective for treatment of varying degrees of nausea and vomiting in pregnancy: Bendectin/Diclectin (doxylamine, pyridoxine, dicyclomine), antihistamine (H(1)) blockers, and phenothiazines; however, the magnitude of effect, particularly for phenothiazines, is in question and may differ among individual agents. Pyridoxine and vitamin B(12)are safe and may be effective. Metoclopramide, droperidol, and ondansetron may be effective, but safety data are insufficient to recommend them as first-line agents. Corticosteroids may not be as beneficial as first thought, and there may be a small teratogenic risk. The relative effectiveness of various agents is largely unknown.

CONCLUSION

Many medications, particularly H(1)-antagonists and phenothiazines, are safe and effective for treatment of varying degrees of NVP.

The vacuous chewing movement (VCM) model of tardive dyskinesia revisited: is there a relationship to dopamine D(2) receptor occupancy?

Tardive dyskinesia (TD) is a late side effect of long-term antipsychotic use in humans, and the vacuous chewing movement (VCM) model has been used routinely to study this movement disorder in rats. Recent receptor occupancy studies in humans and rats have found that antipsychotics given in doses which lead to moderate levels of D(2) receptor blockade can achieve optimal clinical response while minimizing the emergence of acute motor side effects. This suggests that clinicians may have been using inappropriately high doses of antipsychotics. A review of the existing VCM literature indicates that most animal studies have similarly employed antipsychotic doses that are high, i.e. doses that lead to near complete D(2) receptor saturation. To verify whether the incidence or severity of VCMs would decrease with lower antipsychotic doses, we conducted initial experiments with different doses of haloperidol (HAL) given either as repeated daily injections or as depot injections over the course of several weeks. Our results demonstrate that (1) the incidence of VCMs is significantly related to HAL dose, and (2) significant levels of VCMs only emerge when haloperidol is continually present. These findings are consistent with the possibility that total D(2) occupancy, as well as 'transience' of receptor occupation, may be important in the development of late-onset antipsychotic-induced dyskinetic syndromes.

Rabbit syndrome secondary to risperidone

After taking risperidone for 4 months, a 38-year-old man with a major depressive disorder experienced rabbit syndrome. This uncommon extrapyramidal side effect is characterized by rhythmic movements of the mouth and may be caused by typical antipsychotics and risperidone secondary to blockade of dopamine D2 receptors. The syndrome, whose exact mechanism is unknown, responded to anticholinergic treatment in this patient. A literature review indicated that most recent cases have occurred as reactions to the atypical antipsychotic risperidone. Changing treatment to an atypical antipsychotic other than risperidone, such as olanzapine 10 mg/day, may lead to suppression or elimination of the syndrome.

Neuroleptic malignant syndrome presenting as pulmonary edema and severe bronchorrhea

Neuroleptic malignant syndrome is a rare (incidence, 0.02%-3.2%) but dangerous complication following the use of neuroleptic drugs. When not promptly recognized, this disease carries a high mortality (10%-20%) and morbidity rate. We report an unusual case of neuroleptic malignant syndrome that presented predominantly with autonomic instability in the form of recurrent episodes of respiratory distress. The respiratory distress was initially caused by pulmonary edema and later was caused by severe bronchorrhea. We propose that aspiration pneumonia resulting in respiratory failure, the leading cause of death in neuroleptic malignant syndrome, may be a result of a combination of altered mental status and bronchorrhea. This has therapeutic implications because early institution of bromocriptine/dantrolene can prevent aspiration pneumonia and, hence, mortality from respiratory failure.

Photochemical mutagenesis: examples and toxicological relevance

Induction of DNA damage as a consequence of exposure to UV light has been established as the major cause of skin cancer. DNA molecules absorb photon energy directly for wavelengths <320 nm, and lead to well-characterized mutagenic DNA damage. Alternatively, endogenous or exogenous chemicals (sensitizers) may absorb light with the potential of subsequent energy or electron transfer, and lead indirectly to DNA damage. A few light-absorbing pharmaceuticals have long been known to cause photo(geno)toxic effects. Notably, psoralen and chlorpromazine derivatives have been established as photomutagens and the reaction mechanisms have been identified; the fluoroquinolone antibiotics have more recently been recognized as being photomutagenic. The type of DNA damage and the modulation by antioxidants indicate the involvement of reactive oxygen species (ROS), but other mechanisms are also reported for, at least, some derivatives. In routine genotoxicity studies, we observed the photomutagenic activity of a compound (Ro 19-8022) under development as an anxiolytic agent in the Ames tester strain TA102 under normal laboratory illumination conditions. Further investigations showed strong photogenotoxic activity in tests for gene mutations and chromosomal aberrations in mammalian cells. The finding led to the termination of drug development. Another example of a pharmaceutical for which photogenotoxic properties were observed during development is Ro 47-7737, a bisquinoline derivative of the antimalaria compound chloroquine. Also in this case, the photochemical reactivity contributed to the termination of the development process. The risk/benefit assessment for the described compounds has to take into account the human exposure situation, for example, the ability to avoid light exposure during treatment. Consideration of photochemical mutagenesis is specifically important for sunscreen ingredients. The active components of sunscreen lotions are efficient UV absorbers. Consequently, they reduce the genotoxicity of UV light and thus may be considered antimutagens. However, photodegradation to reactive molecules or energy transfer to DNA is possible, in principle, as has been reported for para-aminobenzoic acid (PABA).

[Severe parkinsonism due to metoclopramide in a patient with polypharmacy]

A 73-year-old woman, with tuberculosis of the large intestine, developed nausea as a side effect of the antituberculosis drugs. The nausea was treated with metoclopramide. Subsequently she developed severe medication-induced parkinsonism. As her symptoms initially mimicked a depressive disorder, drug-induced parkinsonism was only considered at a later stage. Due to drug-induced impaired function of the liver and kidney the patient had received a toxic dose of metoclopramide. Treatment with biperiden and withdrawal of the metoclopramide resulted in a reduction of the complaints within 3 months, after which the anti-tuberculosis medication could be reintroduced. Adjusting the dose of metoclopramide could possibly have prevented this severe side effect.

Atropine reduces raclopride-induced muscle rigidity by acting in the ventral region of the striatum

Parkinson-like extrapyramidal motor side effects associated with the use of antipsychotic drugs, such as increased muscle rigidity, are thought to result from blockade of striatal dopamine D2 receptors. While anticholinergic medications (muscarinic receptor antagonists) ameliorate extrapyramidal side effects, the mechanisms underlying their effectiveness remain unclear. We investigated the site of action of atropine, a non-selective muscarinic receptor antagonist, in reducing increased muscle rigidity, assessed as increases in tonic electromyographic (EMG) activity, induced by the selective dopamine D2 receptor antagonist, raclopride. Atropine significantly reduced raclopride-induced EMG increases in rat hindlimb muscles, when injected into the ventral striatum, but not the dorsal striatum or the substantia nigra. Atropine's site of action was localised to a small area of muscarinic receptors within the ventral part of the striatum, using quantitative autoradiography. These findings provide new information about the regulation of motor control by muscarinic receptor antagonists and additional evidence about the functional heterogeneity of the striatum.

Serotonin syndrome caused by selective serotonin reuptake-inhibitors-metoclopramide interaction

OBJECTIVE

To report 2 cases of serotonin syndrome with serious extrapyramidal movement disorders occurring when metoclopramide was coadministered with sertraline or venlafaxine.

CASE SUMMARY

A 72-year-old white woman was treated with sertraline for depression for 18 months and was then admitted to the hospital with a fractured tibia. She was administered metoclopramide because of nausea and, within 2 hours, developed agitation, dysarthria, diaphoresis, and a movement disorder. These symptoms recurred following 2 subsequent administrations of metoclopramide. Treatment with diazepam led to resolution of symptoms within 6 hours, and there was no recurrence at 6 weeks' follow-up. A 32-year-old white woman with major depression was treated with venlafaxine for 3 years. She was admitted following a fall and, after being given metoclopramide, developed movement disorder and a period of unresponsiveness. After a second dose of metoclopramide, these symptoms recurred and were associated with confusion, agitation, fever, diaphoresis, tachypnea, tachycardia, and hypertension. She improved with administration of diazepam, but needed repetition of this treatment over the next 16 hours. Symptoms resolved within 2 days, and she continued venlafaxine with no further adverse effects.

DISCUSSION

Both cases met Stembach's criteria for serotonin syndrome and had serious extrapyramidal movement disorders. The possible pathophysiologic mechanisms for the adverse reactions include a single-drug effect, a pharmacodynamic interaction, and a pharmacokinetic interaction. We believe that a pharmacodynamic interaction is most likely.

CONCLUSIONS

Clinicians should be aware of a risk of serotonin syndrome with serious extrapyramidal reactions in patients receiving sertraline or venlafaxine when metoclopramide is coadministered even in a single, conventional dose.

Torsade de pointes induced by metoclopramide in an elderly woman with preexisting complete left bundle branch block

There is a growing list of drugs implicated in acquired long QT syndrome and torsade de pointes. However, the torsadogenic potential of metoclopramide, a commonly used antiemetic and prokinetic drug, has not been reported in the literature, despite its chemical similarity to procainamide. We report on a 92-year-old woman with preexisting complete left bundle branch block who developed torsade de pointes after intravenous and oral administration of metoclopramide. This patient also developed torsade de pointes when cisapride and erythromycin were given simultaneously. These two episodes were suppressed successfully after discontinuing the offending drugs and administering class IB drugs. This is the first documentation that metoclopramide provokes torsade de pointes clinically. Metoclopramide should be used cautiously in patients with a risk of torsade de pointes.

[Changes in the endocrine system in the course of sulpiride therapy]

The influence of sulpiride, a neuroleptic included into the group of benzamide derivatives, upon endocrine system has been discussed in the article. It is noted that sulpiride clearly increases the evolution of prolactin in both sexes. It gives a chain of various consequences. They are, among others, impairment of gonad activity in both sexes which causes emmeniopathy and galactorrhea in women and impotence in men. The influence of hyperprolactinemia, caused by sulpiride, upon the level of testosterone in plasma and also upon the evolution of progesterone has been also discussed. The knowledge of the influence of sulpiride upon endocrine system is necessary for physicians applying therapy by this medicine. In the article the analysis has been carried out how wider and wider used neuroleptic-sulpiride--influences upon endocrine system and particularly upon the evaluation of prolactin. In the article the main methods of action of the known neuroleptic-sulpiride have been discussed. This is an antiautistic, activizing, antipsychotic and antidepressive action. The other authors used sulpiride in therapy of depressive endogenic syndrome. They obtained a good therapeutic effect. The drug distribution in human organism was also taken into consideration. The mechanism of action of sulpiride and its extrapsychiatric application was also mentioned. The other authors often combines the drug with benzodiazepine derivatives which soothe the fear characteristic of depression.

Cardiopulmonary effects of three different anaesthesia protocols in cats

To develop an alternative anaesthetic regimen for cats with cardiomyopathy, the cardiopulmonary effects of three different premedication-induction protocols, followed by one hour maintenance with isoflurane in oxygen: air were evaluated in six cats. Group I: acepromazine (10 microg/kg) + buprenorphine (10 microg/kg) IM, etomidate (1-2 mg/kg) IV induction. Group II: midazolam (1 mg/kg) + ketamine (10 mg/kg) IM induction. Group III: medetomidine (1.5 mg/m2 body surface) IM, propofol (1-2 mg/kg) IV induction. Heart rate, arterial blood pressure, arterial blood gases, respiration rate, and temperature were recorded for the duration of the experiment. In group I the sedative effect after premedication was limited. In the other groups the level of sedation was sufficient. In all groups premedication resulted in a reduced blood pressure which decreased further immediately following induction. The reduction in mean arterial pressure (MAP) reached statistical significance in group I (142+/-22 to 81+/-14 mmHg) and group II (153+/-28 to 98+/-20 mmHg) but not in group III (165+/-24 to 134+/-29 mmHg). Despite the decrease in blood pressure, MAP was judged to have remained within an acceptable range in all groups. During maintenance of anaesthesia, heart rate decreased significantly in group III (from 165+/-24 to 125+/-10 b.p.m. at t=80 min). During anaesthesia the PCO2 and PO2 values increased significantly in all groups. On the basis of the results, the combination acepromazine-buprenorphine is preferred because heart rate, MAP, and respiration are acceptable, it has a limited sedative effect but recovery is smooth.

Aberrant behavioral effects of a dopamine D1 receptor antagonist and agonist in monkeys: evidence of uncharted dopamine D1 receptor actions

BACKGROUND

Basic research indicates a role for dopamine (DA) D1 antagonism in the treatment of schizophrenia. Clinical trials have not confirmed any role. Besides the defining second messenger (adenylyl cyclase [AC]), DA D1 receptors are linked to other effectors (e.g., phospholipase C [PLC]). Differing actions of DA D1 antagonists upon differing effectors could explain conflicting results between the lab/clinic.

METHODS

In a monkey model in which behavioral effects of DA D1 antagonists/agonists have been well characterized we examined: 1) SKF 83959, biochemically, a DA D1 antagonist, behaviorally a DA D1 agonist, and 2) SKF 83822, biochemically, a DA D1 agonist, which, unlike all previously tested DA D1 agonists, does not also stimulate PLC. SKF 83959 and SKF 83822 were given alone and combined with DA D1 and D2 agonists, antagonists, and dextroamphetamine (AMP).

RESULTS

SKF 83959 acted as a DA D1 agonist (induced oral dyskinesia given alone, counteracted DA D1 antagonist [NNC 756], induced dystonia, and did not inhibit AMP induced behaviors). SKF 83822, unlike previously studied DA D1 agonists, did not induce dyskinesia, but resulted in a state of extreme arousal and locomotor activation without stereotypy, effectively counteracted by NNC 756, but not by SKF 83959 nor raclopride (DA D2 antagonist).

CONCLUSIONS

It is hypothesized that: 1) dyskinesia is linked to PLC stimulation; 2) DA D1 agonism can play a role in the induction of psychosis, via a mechanism linked neither to AC nor PLC, and 3) DA D1 antagonists differ in antipsychotic potential, possibly via this unidentified mechanism.

Oral contraceptives increase the plasma concentrations of chlorpromazine

A 21-year-old female inpatient who was enrolled in a population pharmacokinetic study of chlorpromazine was given an oral chlorpromazine dose of 100 mg three times daily, and plasma concentrations of chlorpromazine were measured weekly. This dose was well tolerated during the first week of therapy. In the second week the patient took a combined oral contraceptive; this was followed by severe dyskinesias and tremor. Plasma chlorpromazine levels were found to be about sixfold higher than those in the first week, although the dose of chlorpromazine had not changed. This observation suggests that the oral contraceptive increased the plasma concentration of chlorpromazine.