Use of lamotrigine in a patient with a clozapine-related seizure

Effect of smoking habits and concomitant valproic acid use on relapse in patients with treatment-resistant schizophrenia receiving clozapine: A 1-year retrospective cohort study

INTRODUCTION

No study has investigated the impact of smoking habits and concomitant valproic acid (VPA) use on clinical outcomes in maintenance treatment with clozapine. Thus, we aimed to examine the effect of smoking habits and concomitant VPA use on relapse during the first year after discharge in patients with treatment-resistant schizophrenia (TRS) receiving clozapine.

METHODS

This retrospective cohort study included patients with TRS who were initiated on clozapine during hospitalization and discharged between April 2012 and January 2021 in two tertiary psychiatric hospitals in Japan. Relapse was defined as rehospitalization due to psychiatric exacerbation during the first year after discharge. A multivariable Cox proportional hazards regression analysis was performed to analyze the effect of smoking habits and concomitant VPA use on relapse. Subgroup analyses were also conducted to examine potential interactions between smoking habits and concomitant VPA use.

RESULTS

Among the included 192 patients, 69 (35.9%) met the criteria of relapse. While smoking habits (adjusted hazard ratio [aHR], 2.27; 95% confidence interval [CI], 1.28-4.01; p < 0.01) independently increased the risk of relapse, a significant interaction for relapse risk was found between smoking habits and concomitant VPA use (p-interaction = 0.015). Concomitant VPA use may be an effective modifier of the increased relapse risk associated with smoking habits. Among patients who smoked, those using VPA concomitantly exhibited a higher risk of relapse (aHR, 5.32; 95% CI, 1.68-16.9; p < 0.01) than those not using VPA (aHR, 1.41; 95% CI, 0.73-2.70; p = 0.30).

CONCLUSION

The findings suggest that the combination of smoking habits and concomitant VPA use may increase the risk of relapse after discharge. Future studies are required to elucidate the mechanisms underlying these findings, such as a decrease in clozapine blood levels.

Low-dose clozapine-related seizure: A case report and literature review

BACKGROUND

Treatment-resistant schizophrenia is a severe form of schizophrenia characterized by poor response to at least two antipsychotic drugs and is typically treated with clozapine. However, clozapine lowers the epileptic threshold, leading to seizures, which are severe side effects of antipsychotics that result in multiple complications. Clozapine-related seizures are generally considered to be dose-dependent and especially rare in the low-dose (150-300 mg/d) clozapine treated population. Due to clinical rarity, little is known about its clinical characteristics and treatment.

CASE SUMMARY

A 62-year-old Chinese man with a 40-year history of treatment-resistant schizophrenia presented to the Emergency Department with symptoms of myoclonus, consciousness disturbance and vomiting after taking 125 mg clozapine. Upon admission, the patient had a suddenly generalized tonic-clonic seizure lasting for about half a minute with persistent disturbance of consciousness, fever, cough and bloody sputum, which was considered to be low-dose clozapine-related seizure. After antiepileptic and multiple anti-infection treatments, the patient was discharged without epileptic or psychotic symptoms.

CONCLUSION

Our aim is to highlight the early prevention and optimal treatment of clozapine-related seizure through case analysis and literature review.

Meloxicam-desmopressin drug-drug interaction producing hyponatremia

BACKGROUND

People with schizophrenia and medical comorbidities are often on multiple medications to manage their symptoms. Herein we present a case of drug-drug interaction (meloxicam and desmopressin), in a patient also on clozapine, that ultimately resulted in hyponatremia and seizure.

METHODS

The patient provided consent to have his case published. We searched PubMed and after reviewing 321 articles, 11 were chosen for relevance.

RESULTS

Meloxicam enhanced the adverse effect (hyponatremia) of desmopressin and was the likely culprit.

CONCLUSIONS

In a patient with higher ADH levels, as in our patient taking desmopressin, the addition of an NSAID could further increase water retention and worsen hyponatremia; indeed, meloxicam was the only new medication added to the patient's regimen, and a drug interaction calculator supports the desmopressin-meloxicam drug-drug interaction as the culprit. We urge clinicians to avoid the use of desmopressin in patients with schizophrenia as this can lead to water intoxication. As meloxicam may worsen desmopressin-induced hyponatremia and could result in seizure, one should avoid using NSAIDs in patients with schizophrenia whom are also prescribed vasopressin/desmopressin. Serum sodium levels should be closely monitored in patients with schizophrenia whose regimen includes desmopressin.

Seizure associated with clozapine: incidence, etiology, and management

Seizures are a known adverse effect of clozapine therapy. The literature varies on incidence rates of seizures, secondary to varying time frames in which each seizure occurred. Tonic-clonic seizures comprise the majority of seizures experienced secondary to clozapine use, but it is imperative to recognize the potential variety of seizure presentation. The exact etiology of clozapine-induced seizure is unknown. Conflicting reports regarding total oral dose, serum concentration, dose titration, and concomitant medications make it difficult to identify a single cause contributing to seizure risk. Following seizure occurrence, it may be in the best interests of the patient to continue clozapine treatment. In this clinical situation, the use of an antiepileptic drug (AED) for seizure prophylaxis may be required. The AED of choice appears to be valproate, but several successful case reports also support the use of lamotrigine, gabapentin and topiramate. Well-designed clinical trials regarding clozapine seizure prophylaxis are lacking. Given clozapine's strong evidence for efficacy in the treatment of schizophrenia and schizoaffective disorder, every attempt to manage side effects, including seizure, should be implemented to allow for therapeutic continuation.

Optimizing clozapine treatment

OBJECTIVE

Clozapine treatment remains the gold standard for treatment-resistant schizophrenia, but treatment with clozapine is associated with several side-effects that complicate the use of the drug. This clinical overview aims to provide psychiatrists with knowledge about how to optimize clozapine treatment. Relevant strategies for reducing side-effects and increasing the likelihood of response are discussed.

METHOD

Studies of clozapine available in MEDLINE were reviewed.

RESULTS

A slow up-titration of clozapine is recommended in order to reach the optimal dosage of clozapine and diminish the risk of dose-dependent side-effects. Particularly, in case of partial response or non-response, the use of therapeutic drug monitoring of clozapine is recommended. Plasma levels above the therapeutic threshold of 350-420 ng/ml are necessary to determine non-response to clozapine. To ease the burden of dose-dependent side-effects, dose reduction of clozapine should be tried and combination with another antipsychotic drug may facilitate further dose reduction. For most side-effects, counteracting medication exists. Augmentation with lamotrigine, antipsychotics, or electroconvulsive therapy may be beneficial in case of partial response to clozapine.

CONCLUSION

Treatment with clozapine should be optimized in order to increase the rate of response and to minimize side-effects, thus diminishing the risk of discontinuation and psychotic relapse.

Clozapine-related EEG changes and seizures: dose and plasma-level relationships

Clozapine is a widely used atypical antipsychotic with a unique effectiveness in treatment-resistant schizophrenia. An important adverse effect is seizures, which have been observed at all stages of clozapine treatment. Valproate has traditionally been considered the drug of choice for the prophylaxis of clozapine seizures, however it may not be the most suitable choice for all patients. There is disagreement as to the best point to prescribe valproate or a suitable antiepileptic: as seizure prophylaxis at a certain clozapine dose or level, or only as remedial treatment. In this review, we examine the relevant literature with an aim to evaluate the following relationships: clozapine dose and electroencephalogram (EEG) abnormalities, plasma levels and EEG abnormalities, dose and occurrence of seizures and plasma levels and occurrence of seizures. Weighted linear regression models were fitted to investigate these relationships. There was a strong relationship between clozapine dose and plasma level and occurrence of clozapine-induced EEG abnormalities. However, a statistically significant relationship between dose and occurrence of seizures was not found. A relationship between clozapine plasma level and occurrence of seizures was not established because of the scarcity of useful data although our review found three case reports which suggested that there is a very substantial risk of seizures with clozapine plasma levels exceeding 1300 μg/l. Seizures are more common during the initiation phase of clozapine treatment, suggesting a slow titration to target plasma levels is desirable. An antiepileptic drug should be considered when the clozapine plasma level exceeds 500 μg/l, if the EEG shows clear epileptiform discharges, if seizures, myoclonic jerks or speech difficulties occur and when there is concurrent use of epileptogenic medication. The antiepileptics of choice for the treatment and prophylaxis of clozapine-induced seizures are valproate (particularly where there is mood disturbance) and lamotrigine (where there is resistance to clozapine).