A Case of Emergent Restless Legs Syndrome With Lurasidone Therapy

Microbial degradation products of lurasidone and their significance in postmortem toxicology

Recent research reported that lurasidone degrades in unpreserved ante-mortem human whole blood inoculated with microorganisms known to dominate postmortem blood specimens. In vitro degradation occurred at a similar rate to risperidone, known to degrade in authentic postmortem specimens until below analytical detection limits. To identify the lurasidone degradation products formed, an Agilent 6520 liquid chromatograph quadrupole-time-of-flight mass spectrometer (LC-QTOF-MS) operating in auto-MS/MS mode was used. Numerous degradation products not previously reported in prior in vitro or in vivo pharmacokinetic studies or forced degradation studies were detected. Accurate mass data, mass fragmentation data, acetylation experiments, and a proposed mechanism of degradation analogous to risperidone supports initial identification of the major degradation product as N-debenzisothiazole-lurasidone (calculated m/z [M + H]⁺  = 360.2646). A standard was unavailable to conclusively confirm this identification. Retrospective data analysis of postmortem cases involving lurasidone identified the presence of the major degradation product in four of six cases where lurasidone was also detected. This finding is significant for toxicology laboratories screening for this drug in postmortem casework. The major postmortem lurasidone degradation product has consequently been added to the LC-QTOF-MS drug screen at Forensic Science SA (FSSA) to indicate postmortem lurasidone degradation in authentic postmortem blood specimens and as a marker of lurasidone administration in the event lurasidone is degraded to concentrations below detection limits.

Risk Analysis of Lurasidone in Patients with Schizophrenia and Bipolar Depression

Lurasidone was approved by the United States Food and Drug Administration (FDA) for the treatment of schizophrenia, as well as for the treatment of bipolar depression. However, emerging reports have indicated various adverse drug reactions with the use of lurasidone. Thus, in this article, we have analyzed the risk profile of lurasidone in the established therapeutic indication. A total of 419 studies were published from October 2010-July 2019 regarding lurasidone. After the inclusion and exclusion criteria, 17 studies were selected for the analysis of risk. The adverse drug reactions (ADRs) of these studies were categorized as per the innovator summary of product characteristics (SmPC). Finally, the unlisted ADRs were analyzed by using the Naranjo probability algorithm. Telogen effluvium, thrombocytopenia, restless leg syndrome and hypersexuality were found with the use of lurasidone and fall under the unlisted category. The causality assessment has shown a probable correlation of lurasidone with hypersexuality, restless leg syndrome, thrombocytopenia and possible relation with telogen effluvium. In conclusion, lurasidone is a novel and efficacious pharmacological treatment for bipolar depression and schizophrenia. However, more data regarding the safety of this drug in a large population is needed.

Drug-Induced Restless Legs Syndrome

OBJECTIVE

To review the literature on drug-induced restless legs syndrome (DI-RLS).

DATA SOURCES

The review included a search for English-language literature from 1966 to December 2017 in the MEDLINE, PubMed, and Ovid databases using the following search terms: restless legs syndrome (RLS), periodic limb movement, adverse effects, and drug-induced. In addition, background articles on the pathophysiology, etiology, and epidemiology of RLS were retrieved. Bibliographies of relevant articles were reviewed for additional citations.

STUDY SELECTION AND DATA EXTRACTION

All case reports, case series, and review articles of DI-RLS were identified and analyzed. There were only a small number of controlled clinical trials, and most data were from case reports and case series.

RESULTS

Several drugs and drug classes have been implicated in DI-RLS, with antidepressants, antipsychotics, and antiepileptics having the most evidence. In addition, RLS may be linked with a number of disorders or underlying predisposing factors as well.

CONCLUSIONS

The prevalence of RLS is variable and ranges from 3% to 19% in the general population. There are many predisposing factors to RLS, but an emerging body of evidence suggests that there is an association between numerous drugs and RLS.