Prise en charge ambulatoire des patients atteints de fibromyalgie par kétamine par voie sous-cutanée : que nous apprend la pratique ? Étude rétrospective observationnelle au CHU de Grenoble

Fibromyalgia (FM) pathophysiology remains largely unknown and its management therefore difficult. In this disorder, sub-cutaneous ketamine treatment in the patient's home is increasingly prescribed, as in-hospital pharmacies can directly deliver the drug to outpatients by way of derogation. This off-label use of ketamine raises some concerns. In order to evaluate local practices, a retrospective observational study was conducted at Grenoble teaching hospital among FM patients chronically (> 3 months) treated with ketamine on an outpatient basis. Fifty-nine patients were included; half were treated for more than 4-5 years with mean weekly dosage greater or equal to 100 mg/week for 55% of them. Overall subjective efficacy of treatment was satisfactory (in more than 80% of patients). Ketamine dose escalation had been necessary for 80% of patients (during the first 6 months in 53%). Lastly, 50% of patients had experienced side effects, mostly psychodysleptic symptoms. Four cases of withdrawal syndromes occurred even though treatment had been discontinued gradually. Our results suggest the following actions: validation of dosage determination that includes body weight, tracking of associated pain medication, implementation of validated tools to evaluate efficacy, monitoring and management of side effect, pharmacodynamic tolerance and drug dependency. The health professionals wish to structure and coordinate their actions and are currently working to develop and test a novel protocol of care for the management of FM outpatients treated by ketamine.