Neuroleptic Malignant Syndrome with Delayed Onset of Fever Following Risperidone Administration

Atypical Neuroleptic Malignant Syndrome: Case Reports and Diagnostic Challenges

Neuroleptic malignant syndrome caused by atypical antipsychotic drugs may present in an atypical manner without symptoms such as hyperthermia and/or muscle rigidity. A detailed description of atypical neuroleptic malignant syndrome induced by atypical antipsychotic drugs, practical information to distinguish neuroleptic malignant syndrome from other related conditions, and the diagnostic criteria that may be used to settle the diagnosis of atypical neuroleptic malignant syndrome are highlighted in this paper. This study was conducted searching PubMed and Science Direct, resulting in 525 articles. 26 case reports that met inclusion criteria were identified. Atypical neuroleptic malignant syndrome was found to develop mainly in male patients suffering from schizophrenia (14 cases) and bipolar disorder (2), and was induced by clozapine (6 cases), olanzapine (5 cases), aripiprazole and quetiapine (4 cases). Muscle rigidity did not develop in patients treated with clozapine and quetiapine, whereas a lack of hyperthermia was common with aripiprazole and clozapine treatment. Atypical neuroleptic malignant syndrome is a difficult matter, especially when symptoms of hyperthermia or muscle rigidity is lacking, but using Levenson's or Adityanjee and Aderibigbe's criteria may increase it detectability, can permit earlier intervention and prevent development of life-threatening typical neuroleptic malignant syndrome.

Functional SNPs in Genes Encoding the 5-HT2A Receptor Modify the Affinity and Potency of Several Atypical Antipsychotic Drugs

Atypical antipsychotic drugs (AADs) are the standard treatment for both the acute and long-term management of schizophrenia and an augmentation to mood stabilizers for bipolar disorder (BD). Yet many individuals who take AADs do not fully respond to them, while others experience side effects that include weight gain and metabolic disorder. This in vitro pharmacogenetic study examined whether allelic variants in the 5-hydroxytryptamine (HT)2A receptor alter the in vitro pharmacology of six AADs (clozapine, olanzapine, risperidone, quetiapine, ziprasidone, and aripiprazole). We selected 4 functional single-nucleotide polymorphisms (SNPs) for investigation (Thr25Asn, Ile197Val, Ala447Val, and His452Tyr), conducted site-directed mutagenesis studies to induce variants into human HEK-293 cell lines, and screened allelic variants for their effects on 5-HT 2A receptors in the cell lines. We conducted numerous binding assays and fluorescence-based assay system (FLEX station) experiments using the six AADs. Our results indicated that three polymorphic 5-HT2A receptors (Ile197Val, Ala447Val, and His452Tyr) exhibited statistically significant, though modest, changes in atypical antipsychotic affinity. In addition, three polymorphic receptors (Thr25Asn, Ile197Val, and His452Try) altered AAD potency. Our findings support in vivo evidence that functional SNPs in genes encoding neuroreceptor drug targets could explain interindividual differences in AAD drug response and tolerability. We suggest that more in vivo pharmacogenetic studies of well-characterized patients who are prescribed AADs be indicated. Future pharmacogenetic studies of well-characterized patients will likely involve tagging SNPs and the use of haplotypes related to other genes encoding neuroreceptor drug targets.

Thalidomide- and Lenalidomide-Associated; Thromboembolism; NMS with Delayed Fever Associated with Risperidone Another Interesting Adverse Effect to Risperidone – Priapism; Hyperlactatemia due to Nevirapine; Recurrent Anaphylaxis with Gonadotropin-Releasing Hormone Analogs; Psychotropic Effects of Antiepileptic Drugs; Literacy and Misunderstanding of Prescription Drug Labels

The purpose of this feature is to heighten awareness of specific adverse drug reactions (ADRs), discuss methods of prevention, and promote reporting of ADRs to the FDA's medWatch program (800-FDA-1088). If you have reported an interesting preventable ADR to medWatch, please consider sharing the account with our readers. Write to Dr. Shuster at ISMP, 1800 Byberry Road, Suite 810, Huntingdon Valley, PA 19006 (call 215-947-7797; fax 215-914-1492; E-mail: joel.shuster@temple.edu ). Your report will be published anonymously unless otherwise requested. This feature is provided by the Institute for Safe Medication Practices in cooperation with the FDA's medWatch Program and Temple University School of Pharmacy. ISMP is an FDA medWatch partner.