Effects of adjunctive verapamil administration in chronic schizophrenic patients

Treatment of drug-resistant chronic schizophrenics with an association of neuroleptics and the calcium antagonist nimodipine

Nimodipine was administered at the daily dose of 90 mg po, for 30 days, to ten chronic undifferentiated schizophrenics, eight men and two women, aged 31-35 years, maintained on previously longlasting neuroleptic treatments. In five patients, a placebo period of 15 days preceded the administration of the drug. Monitoring of psychiatric symptomatology by the Brief Psychiatric Rating Scale (BPRS) revealed significant nimodipine-induced improvement. However, the Andreasen Rating Scale for Positive Symptoms (SAPS) showed favourable effects only in the five patients who had not received placebo, while in the others both SAPS and the Andreasen Rating Scale for Negative Symptoms (SANS) showed no significant effect of therapy. The Tardive Dyskinesia Scale revealed no improvements of neurological symptoms after either placebo or drug treatment. Measurement of plasma MHPG concentrations revealed no significant changes induced by either placebo or nimodipine, while HVA plasma levels showed a trend toward decrease, and prolactin a trend toward increase, after nimodipine.

From Gene to Behavior: L-Type Calcium Channel Mechanisms Underlying Neuropsychiatric Symptoms

The L-type calcium channels (LTCCs) Cav1.2 and Cav1.3, encoded by the CACNA1C and CACNA1D genes, respectively, are important regulators of calcium influx into cells and are critical for normal brain development and plasticity. In humans, CACNA1C has emerged as one of the most widely reproduced and prominent candidate risk genes for a range of neuropsychiatric disorders, including bipolar disorder (BD), schizophrenia (SCZ), major depressive disorder, autism spectrum disorder, and attention deficit hyperactivity disorder. Separately, CACNA1D has been found to be associated with BD and autism spectrum disorder, as well as cocaine dependence, a comorbid feature associated with psychiatric disorders. Despite growing evidence of a significant link between CACNA1C and CACNA1D and psychiatric disorders, our understanding of the biological mechanisms by which these LTCCs mediate neuropsychiatric-associated endophenotypes, many of which are shared across the different disorders, remains rudimentary. Clinical studies with LTCC blockers testing their efficacy to alleviate symptoms associated with BD, SCZ, and drug dependence have provided mixed results, underscoring the importance of further exploring the neurobiological consequences of dysregulated Cav1.2 and Cav1.3. Here, we provide a review of clinical studies that have evaluated LTCC blockers for BD, SCZ, and drug dependence-associated symptoms, as well as rodent studies that have identified Cav1.2- and Cav1.3-specific molecular and cellular cascades that underlie mood (anxiety, depression), social behavior, cognition, and addiction.

Clozapine-induced Supraventricular Tachycardia and its Treatment with Verapamil

Clozapine is known to be an effective antipsychotic for schizophrenia. Cardiovascular complications associated with initiation of clozapine include tachycardia, postural hypotension, and myocarditis. Factors associated with development of cardiovascular adverse events are not clearly known, and dose titration has been described to be one among the associated risk factors. We report a case of a 45-year-old man with treatment resistant schizophrenia who developed supraventricular tachycardia during initiation of clozapine and discuss the role of verapamil in its successful management.

NMDA receptor antagonist effects, cortical glutamatergic function, and schizophrenia: toward a paradigm shift in medication development

There is an urgent need to improve the pharmacotherapy of schizophrenia despite the introduction of important new medications. New treatment insights may come from appreciating the therapeutic implications of model psychoses. In particular, basic and clinical studies have employed the N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, ketamine, as a probe of NMDA receptor contributions to cognition and behavior. These studies illustrate a translational neuroscience approach for probing mechanistic hypotheses related to the neurobiology and treatment of schizophrenia and other disorders. Two particular pathophysiologic themes associated with schizophrenia, the disturbance of cortical connectivity and the disinhibition of glutamatergic activity may be modeled by the administration of NMDA receptor antagonists. The purpose of this review is to consider the possibility that agents that attenuate these two components of NMDA receptor antagonist response may play complementary roles in the treatment of schizophrenia.

Calcium channel blockers in psychiatric disorders: a review of the literature

OBJECTIVES

To review the published literature of the past 15 years regarding use of calcium channel blockers (CCBs) in psychiatric practice. These drugs, especially verapamil, have been recommended as possible treatments for mania and other disorders.

METHODS

The Cumulative Medical Index and other databases were searched and back-tracked to locate relevant articles. Sixty-one such articles were uncovered: 37 anecdotal reports, 7 partially controlled reports, and 17 controlled trials.

RESULTS

Most studies involved treatment of mania using verapamil. Although anecdotal reports were generally favourable, results from partially controlled reports or controlled clinical trials were mixed. Generally, verapamil was less effective than was lithium or placebo. Treatment of depression with CCBs was not very successful, regardless of the type of trial; the best trial was negative. The same was true for the treatment of schizophrenia, although the cases studied were extremely chronic and treatment-resistant. Evidence for efficacy in other illnesses, such as Alzheimer's disease or tardive dyskinesia was scanty but suggested that further trials might be in order.

CONCLUSIONS

CCBs do not at present have an established place in psychiatric treatment. Nonetheless, clinicians faced with a manic patient not responsive to other antimanic drugs, either alone or in combination, might consider adding verapamil as an adjunct. A study bearing on this specific issue is needed to determine whether or not such off-label use would really be justified.

Verapamil for severe hyperkinetic movement disorders

The use of verapamil in three cases of severe hyperkinetic movement disorders resulted in dramatic improvement in patients who had been refractory to many other treatments over a prolonged period. A videotape illustration of one of the patients is provided. The mechanism of action and evidence of efficacy of calcium-channel blockers for abnormal movements are discussed.

Nilvadipine is effective for chronic schizophrenia in a double-blind placebo-controlled study. off

We investigated the efficacy of nilvadipine, a calcium channel inhibitor, for psychiatric symptoms and tardive dyskinesia in 30 patients with chronic schizophrenia in a placebo-controlled double-blind crossover study. The total scores of the Brief Psychiatric Rating Scale decreased significantly when the patients were on nilvadipine compared with placebo. Improvement was particularly significant in emotional withdrawal and uncooperativeness. Nilvadipine was not effective, however, for tardive dyskinesia. No adverse effects, such as hypotension, occurred.

Effectiveness of nilvadipine in two cases of chronic schizophrenia

Nilvadipine is a calcium channel inhibitor used commonly for the treatment of cerebrovascular insufficiency. We observed two patients with schizophrenia whose psychiatric symptoms and tardive dyskinesia improved after the addition of nilvadipine to their antipsychotic drug regimen. The total score of the brief psychiatric rating scale (BPRS) in case 1 fell from 56 to 42 after 8 weeks on nilvadipine; while that of case 2 fell from 44 to 32. The total score of the abnormal involuntary movement scale (AIMS) in case 2 decreased from 12 to 7. No adverse effects occurred during treatment. Nilvadipine may thus offer a new approach to the adjunctive treatment of schizophrenia.

Effects of nimodipine and/or haloperidol on the expression of conditioned locomotion and sensitization to cocaine in rats

The development of classical conditioning of cocaine's locomotor effects can be dissociated from the development of sensitization to cocaine by co-administration of haloperidol, a dopamine D2-like receptor antagonist, and nimodipine, an L-type calcium channel antagonist. The effects of these agents on the expression of conditioning and sensitization are described in the present report. Rats were given injections of vehicle or cocaine (10 mg/kg, IP) for 10 days before placement in a specific context in which locomotor activity was recorded. Neither haloperidol (0.05 mg/kg, IP) nor nimodipine (10 mg/kg, SC) influenced the expression of classical conditioning of cocaine's locomotor effects to the situational context on a subsequent cocaine-free test. Combined treatment of rats with both drugs did block classical conditioning with cocaine. Nimodipine, but not haloperidol, blocked the expression of behavioural sensitization to cocaine after a cocaine challenge. It is concluded that the expression of cocaine-induced classical conditioning can be pharmacologically dissociated from the expression of behavioural sensitization to cocaine. Furthermore, the effects of nimodipine and haloperidol on the expression of conditioning and sensitization are different from their effects on the development of these phenomena.

Calcium channel blockade interacts with a neuroleptic to attenuate the conditioning of amphetamine's behavioral effects in the rat

Conditioned responses to drug-related cues appear to be related to the maintenance of stimulant addiction. These conditioned responses are not blocked by treatments that block the direct effects of stimulants and may contribute to the high rate of relapse of addicts. Rats administered (+)-amphetamine in a specific environment exhibit conditioned locomotion when subsequently placed in that environment without drugs. The neuroleptic haloperidol significantly attenuated amphetamine-induced locomotor activity but failed to reduce conditioned locomotion. Nimodipine, an L-type calcium channel antagonist, had no effect on amphetamine-induced unconditioned or conditioned locomotion. However, combined nimodipine and haloperidol treatment blocked the unconditioned and attenuated the conditioned locomotor response to amphetamine. Conjunctive therapy with nimodipine and haloperidol may provide an efficacious treatment for stimulant addiction. In addition, nimodipine may provide an important adjunctive therapy for schizophrenia, allowing the use of lower doses of neuroleptic to avoid extrapyramidal side effects.

Smithkline Beecham Prize for Young Psychopharmacologists: A review of the relationship between calcium channels and psychiatric disorders

The symptoms and etiology of most major psychiatric disorders probably represent an underlying disturbance of neurotransmitter function. Understanding the mechanisms which control neurotransmitter function, and in particular neurotransmitter release, is therefore of considerable importance in determining the appropriate pharmacological treatment for these disorders. Calcium entry into neurons triggers the release of a wide range of neurotransmitters and recently our understanding of the mechanisms which control neuronal calcium entry has increased considerably. Neuronal calcium entry occurs through either voltage-sensitive or receptor-operated calcium channels. This article reviews the different subtypes of calcium channel, with particular reference to their structure; drugs which act upon them; and the possible function of the subtypes identified to date. In addition, it reviews the potential role of calcium channel antagonists in the treatment of a wide range of psychiatric disorders, and concludes that these drugs may have an increasing therapeutic role particularly in the treatment of drug dependence, mood disorders and Alzheimer's disease.

Psychopharmacological properties of calcium channel inhibitors

The previous decade has witnessed a major expansion of knowledge of the role played by voltage-sensitive calcium channels in the function of the central nervous system. Significant progress in the field has been made possible with the broadening use of organic calcium channel inhibitors (CCIs, Ca2+ antagonists), until recently considered almost exclusively as peripherally active antianginal and antiarrhythmic drugs. CCIs, however, do penetrate the blood-brain barrier from the periphery. Autoradiographic studies have established a highly heterogeneous distribution of CCI recognition sites within the brain. The existing evidence suggests that CCIs have marked psychotropic properties. The profile of their central activity is unique and spans a wide range of effects. Nevertheless, question regarding potentially confounding potent peripheral effects of these drugs remain. This paper reviews the psychopharmacology of CCIs, concentrating on preclinical data, but including supportive clinical and biochemical evidence as well. It focuses on these drugs' antidepressant, antidopaminergic (neuroleptic-like), anxiolytic and anticonvulsant effects. CCIs may also modify the reinforcing properties of some addictive drugs.