Severe laryngeal dystonia in a patient receiving zuclopenthixol "Acuphase" and fluoxetine.
OBJECTIVE
Prescribers are warned to be vigilant for potential cytochrome P450 mediated drug interactions; guidelines separately highlight risks of toxicity associated with zuclopenthixol acuphase. We previously examined potential cytochrome P450 interactions with zuclopenthixol and here describe dangerous side effects in a patient receiving zuclopenthixol acuphase and the selective serotonin reuptake inhibitor fluoxetine at high dose.


METHODS
We present the case of a patient established on fluoxetine 80 mg/day who subsequently received injected zuclopenthixol acuphase 100 mg.


RESULTS
Following zuclopenthixol acuphase administration, dangerous extra-pyramidal side effects were observed, including severe laryngeal dystonia necessitating emergency medical treatment.


CONCLUSIONS
Our observations of symptoms of zuclopenthixol toxicity are consistent with a cytochrome P450 2D6/3A4 interaction with fluoxetine. Previous evidence demonstrating this interaction included only patients taking fluoxetine up to 60 mg/day. This case extends the evidence base. In patients taking high dose fluoxetine, we advise marked reductions in the prescribed dose of zuclopenthixol acuphase.
Hood
Sean
S
School of Psychiatry & Clinical Neurosciences (M521), University of Western Australia, QEII Medical Centre, Perth, WA, Australia. sean.hood@uwa.edu.au
Orr
Kenneth
K
Bennett
Lynette
L
Davies
Simon
S
D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects*; D003006:Clopenthixol / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D003865:Major Depressive Disorder / Q000188:drug therapy*; D004347:Drug Interactions; D004359:Drug Therapy, Combination / Q000009:adverse effects*; D004421:Dystonia / Q000139:chemically induced*; D005260:Female; D005473:Fluoxetine / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D007821:Laryngeal Muscles / Q000187:drug effects; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage / Q000009:adverse effects*
D014150:Antipsychotic Agents; D003006:Clopenthixol; D005473:Fluoxetine; D017367:Selective Serotonin Reuptake Inhibitors; C060342:clopenthixol acetate ester