Neuroleptic malignant syndrome with antidepressant/antipsychotic drug combination

Optimizing antidepressant and clozapine co-prescription in clinical practice: A systematic review and expert recommendations

OBJECTIVES

To synthesize the information relevant for clinical practice on clozapine-antidepressant co-prescription concerning pharmacokinetic drug-drug interactions (DDI), adverse drug reactions (ADRs) associated with the co-prescription, antidepressant add-on for clozapine-resistant symptoms and antidepressant add-on for clozapine-induced ADRs.

METHODS

Articles were identified with MEDLINE, Web of Sciences and PsycINFO search from inception through April 2023. Data were synthesized narratively.

RESULTS

ADRs are most often induced by the co-prescription of antidepressants that inhibit CYP enzymes (fluvoxamine, fluoxetine, paroxetine). Fluvoxamine add-on is hazardous because of its potent inhibition of clozapine metabolism and has few indications (lowering daily number of clozapine tablets, reducing norclozapine-induced metabolic disturbances and other dose-dependent clozapine-induced ADRs). ADR frequency may be reduced by therapeutic drug monitoring and knowledge of other factors impacting clozapine metabolism (pneumonia, inflammation, smoking, etc.). Improvement of negative symptoms is the most documented beneficial effect of antidepressant add-on for clozapine-resistant psychotic symptoms. The add-on antidepressant should be chosen according to its safety profile regarding DDI with clozapine: antidepressants inhibiting clozapine metabolism or increasing the anticholinergic load should be avoided. Other indications of antidepressant add-on (affective or obsessive compulsive symptoms, sialorrhea, and enuresis) are poorly documented.

CONCLUSION

Antidepressant add-on to clozapine is associated with potential benefits in clozapine users as this strategy may contribute to reduce the burden of clozapine-resistant symptoms or of clozapine-induced ADRs. Further studies are needed to determine whether antidepressant add-on can reduce the risk of clozapine discontinuation.

Association Between Selective Serotonin-Reuptake Inhibitors, Second-Generation Antipsychotics, and Neuroleptic Malignant Syndrome

Objective

To review the published reports of neuroleptic malignant syndrome (NMS) associated with the use of selective serotonin-reuptake inhibitors (SSRIs) and second-generation antipsychotics.

Data Source:

Information was selected from a MEDLINE search of English-language literature (1950–May 2008). Manual search of all published cases indexed in MEDLINE (English language only) of NMS associated with second-generation antipsychotics was also performed.

Study Selection And Data Extraction:

Pertinent information from all reports obtained was included, with specific emphasis on patient age, sex, second-generation antipsychotic involved, SSRI or other antidepressant involved, time of onset of NMS symptoms in relation to medication changes, treatment administered, and outcome of the reaction.

Data Synthesis:

NMS has been reported with every second-generation antipsychotic agent. It is unclear whether concomitant therapy with other agents may increase the risk of NMS development via pharmacodynamic or pharmacokinetic mechanisms or both, The suggested pharmacodynamic mechanism for increased risk of NMS with concomitant use of SSRIs is the effect of serotonin on dopamine release. Serotonin further inhibits dopamine release and thereby may worsen a hypodopaminergic state induced by antipsychotics. Pharmacokinetic factors may also play a role in some NMS cases involving an SSRI by increasing antipsychotic concentrations. An examination of case reports seems to indícale that at least in some casos, a temporal relationship exists with the addition of an SSRI to existing antipsychotic therapy.

Conclusions:

The use of SSRIs may be associated with an increased risk of NMS development in (hose receiving second-generation antipsychotics. Clinicians should closely monitor patients for the potential development of NMS.

Fatal neuroleptic malignant syndrome in a previously long-term user of clozapine following its reintroduction in combination with paroxetine

A 77-year-old patient with initial behavioral and psychological symptoms of dementia was treated with clozapine (50 mg/daily). Since no clinical benefit was apparent, clozapine was discontinued after six weeks and the patient started on paroxetine (20 mg/daily). After three weeks on paroxetine, he was given another trial of clozapine at a starting dosage of 25 mg/daily. While clozapine had previously been well tolerated, this time he rapidly developed fever, mental confusion, lethargy, muscle spasms and rigidity. The diagnosis of neuroleptic malignant syndrome was delayed, because there was no leukocytosis and serum creatine phosphokinase was initially not elevated. Subcutaneous apomorphine was then given but, after an initial improvement, the patient developed a multiple organ failure syndrome and died.

Neuroleptic malignant syndrome induced by atypical antipsychotics

A review of the English literature confirms that neuroleptic malignant syndrome (NMS) occurs with both traditional and atypical antipsychotic medications. Published reports of NMS induced by the traditional antipsychotics have given the practitioner valuable information on the prevention and treatment of this adverse effect. Case reports have also been published concerning NMS and clozapine, risperidone, olanzapine and quetiapine. By evaluating the case reports of atypical antipsychotic-induced NMS, valuable information may be obtained concerning similarities or differences from that induced by the traditional antipsychotics. The case reports of NMS with atypical antipsychotics were evaluated for diagnosis, age/sex of patient, risk factors, antipsychotic doses and duration of use, symptoms of NMS, and clinical course.