Low-Dose Sublingual Ketamine Does Not Modulate Experimentally Induced Mechanical Hyperalgesia in Healthy Subjects
Pain Medicine, 08/10/2012
Slater H et al. – In comparison with placebo, a single low–dose sublingual pharmacological intervention targeting the processes of sensitization via antagonism of N–methyl–d–aspartate (NMDA) receptors did not modulate the effects of acute experimentally induced mechanical hyperalgesia, suggesting a higher dose or repeat doses may be required.Methods
- Two groups (N = 11/group) of age– and sex–matched healthy subjects performed eccentric exercise using the nondominant arm wrist extensors (time 0) to induce muscle soreness 24 hours later (time 1).
- Immediately prior to exercise, subjects were administered either a 25 mg ketamine lozenge or a placebo.
- At time 1, experimental muscle pain was augmented by injection of hypertonic saline into the extensor carpi radialis brevis (ECRB) muscle of the exercised arm.
- Pressure pain thresholds (PPTs), muscle soreness, muscle pain intensity (electronic visual analog scale [VAS]), and maximal wrist extension force were assessed at time 0 (pre– and postexercise) and at time 1 (pre–, during, and post saline–induced pain).
- Regardless of group, PPT was reduced at ECRB (P < 0.021) and at the common extensor origin (P < 0.034) at time 1 preinjection compared with time 0 pre–exercise.
- At time 1, elevated levels of muscle soreness and force attenuation were similar between groups compared with time 0 pre–exercise (P < 0.0001), and similar hypertonic saline–induced pain areas and pain intensity profiles were evident.