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Toxins in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Thioridazine is an antipsychotic agent. Use can result in decreased vision and dyschromatopsia. On clinical exam, macular pigmentary changes can develop into a “salt-and-pepper” pattern.
Folie à deux (et folie à plusiers)
Published in David Enoch, Basant K. Puri, Hadrian Ball, Uncommon Psychiatric Syndromes, 2020
David Enoch, Basant K. Puri, Hadrian Ball
Both patients were prescribed thioridazine and improved behaviourally. However, on discharge they did not attend for follow-up or visit their doctor for further prescriptions. Stanley began paying his bills until recently, when he again started to write bizarre letters, and the local police received a complaint about a clash with a neighbour.
Dopamine and Tumorigenesis in Reproductive Tissues
Published in Nira Ben-Jonathan, Dopamine, 2020
A more recent study reported that two human ovarian cancer cell lines, A2780 and SKOV3, express D2R, as determined by Western blotting analysis [73]. Cell incubation with thioridazine induced apoptosis and autophagy, which were attributed to increased reactive oxygen species (ROS) and the associated DNA damage. In addition, heme oxygenase 1, NAPDH quinone dehydrogenase 1, hypoxia inducible factor-1α, and phosphorylated (p)-protein kinase B expression all were significantly decreased, while the expression of MAP kinase increased. Moreover, treatment with thioridazine for 3 weeks in mice engrafted with SKOV3 xenografts caused a 50% reduction in tumor volume. The authors concluded that thioridazine may be used as a potential drug in ovarian cancer therapy.
Phenylalanine 4-monooxygenase: the “sulfoxidation polymorphism”
Published in Xenobiotica, 2020
Stephen C. Mitchell, Glyn B. Steventon
Although the numbers in these early studies were small, they served to provide an indication that individuals may vary in their ability to undertake xenobiotic sulfoxidation and that this could be associated with clinical consequences. Such phenothiazine sulfoxidation is now known to be undertaken by microsomal enzymes, notably the cytochromes P450 (Steventon, 1996; Ziegler, 1982). Indeed, a study of 24 patients receiving thioridazine highlighted one individual who had relatively low plasma levels of the oxidised metabolites, mesoridazine (thioridazine side-chain sulfoxide) and sulforidazine (thioridazine side-chain sulfone), and consequently suffered over-sedation on a conventional dosing regimen. This individual, unlike the majority, was shown to be a poor metaboliser of dextromethorphan and hence have a relative inefficiency in cytochrome P450 2D6 activity (Meyer et al., 1990). The cytochrome P450 superfamily is pursued in other articles in this special edition.
Focus on eye care in schizophrenia
Published in Clinical and Experimental Optometry, 2019
Another phenothiazine antipsychotic medication, thioridazine, is known to rarely result in photoreceptor toxicity that ultimately manifests as progressive atrophy of the retinal pigment epithelium (RPE) layer. Heralding visual symptoms of retinotoxicity include blurred vision, dyschromatopsia, scotomas, and nyctalopia which can present at any time point during treatment, up to two weeks after initiation of the drug.2018 Early clinical signs of thioridazine‐induced retina toxicity include RPE mottling or clumping with the potential for geographic chorioretinal atrophy involving the macula and posterior pole. Patients taking thioridazine should be monitored closely at the start of the treatments and periodically thereafter to detect any retinotoxic reaction that may develop, especially high‐risk daily dosages of more than 800 mg per day. Retinal monitoring should continue even after cessation of therapy since remote damage can occur.2018
Two cases of priapism associated with Quetiapine
Published in Psychiatry and Clinical Psychopharmacology, 2018
Özge Şahmelikoğlu Onur, Hatice Kızılkale, Hüseyin Yumrukçal, Meltem Gürü
Various drugs have been implicated in priapism. Antipsychotic medications have varying affinities for adrenergic receptors. Although being rare, priapism is a well-known side effect that occurs with first generation antipsychotics; a few cases have also been reported with second generation antipsychotics. Ziprasidone and risperidone have the highest affinity, followed by clozapine and quetiapine for adrenergic receptors [4]. Priapism is attributed to the blockade of alpha-1 adrenergic receptors in corpus cavernosum. This side effect was previously thought to be associated with the use of typical antipsychotics, notably, thioridazine. Atypical antipsychotics, due to their favourable side effect profiles, are being prescribed ever more often and are considered to cause priapism infrequently. However, this side effect has been reported in patients taking ziprasidone, risperidone, clozapine, quetiapine, aripiprazole and olanzapine. The affinity of these drugs to alpha-1 adrenergic receptors vary significantly; affinity of quetiapine, compared to other antipsychotics is intermediate [5].