Nowadays, available drugs cannot always produce pain relief in patients with neuropathic pain disease. It is believed that drugs acting as antagonists of the N-methyl-D-aspartic acid (NMDA) receptor may have been efficient in the treatment of neuropathic pain disorders. Ketamine is the only NMDA receptor antagonist commercially available in France. Ketamine is usually administered intravenously for surgical anesthesia. The intravenous administration of ketamine will be difficult to manage in the treatment of chronic neuropathic pain. Some trials using oral ketamine for the treatment of neuropathic pain were conducted but results were heterogeneous. This may be explained by the different range of ketamine doses tested. The aim of this clinical trial is to identify a safe and an efficient dose of orally administrated ketamine for the treatment of peripheral neuropathic pain. The clinical trial will be conducted in Toulouse Hospital, France. This study is a randomized, double-blind, placebo-controlled trial. The study will be conducted using 4 parallel groups (three doses of ketamine versus placebo).
In previous studies, it was shown that when ketamine was administrated by the intravenous route, its analgesic action was rapid. In one study, when oral ketamine was administrated to patients suffering from neuropathic pain, in six out of nine patients, pain was relieved after 24 hours post-administration. In this study, ketamine will be administrated during seven days, which will allow us to evaluate ketamine efficiency and safety. The effect of ketamine on pain intensity will be mainly studied using a visual analogue scale (VAS) but also taking into account the score assigned by the patient to his pain. This score will be noted down by patients before, during and after ketamine treatment. Evaluation of benefit/risk for ketamine administration during this trial, shows that even if adverse events are not excluded, the benefit for the patients may be neuropathic pain relief. Because clinical current knowledge regarding oral administration of ketamine is limited, this trial intends to enlarge information about ketamine efficiency and safety, more particularly in neuropathic pain disorders.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
QUADRUPLE
Enrollment
22
Initial dosage: 250 mg/5 ml Three doses of ketamine will be tested: * 0.35 mg/kg * 0.7 mg/kg * 1.4 mg/kg Each patient will receive the indicated dose of oral ketamine or placebo once and if there are not adverse events, he will be able to continue the treatment three times a day, during 7 days (between visit 2 and 3). The oral ketamine will be administered in form of syrup.
Service de Neurochirurgie
Toulouse, France
Evaluation of pain intensity using a 10 cm visual analogue scale (VAS) (0 = no pain; 10 = worst possible pain) before and after 7 days of oral administration of one of the three doses of ketamine or placebo.
Time frame: V1 (14 days before ketamine treatment), at V2 (before oral administration of one of the three doses of ketamine or placebo), at V3 (after 7 days of oral administration), and at V4 (after 7 days of the end of treatment)
Pain intensity will be evaluated by measuring thermal sensibility. A thermode will be used to determine the heat and cold pain thresholds (thermotest) and by measuring hyperalgesia
Time frame: Thermotest and hyperalgesia will be assessed at T0 and T1 hour, at visit 2 and visit 3
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