The effect of the GABA-agonist, progabide, on stretch and flexor reflexes and on voluntary power in spastic patients.
The action of the GABA-receptor agonist, progabide , was investigated in a double-blind study with cross-over to placebo. The stretch and flexor reflexes and voluntary power were measured in 16 patients with spasticity. 2-week treatment periods were used; the median daily oral dosage of progabide was 24.3 mg/kg. The Achilles tendon (T) reflex was significantly suppressed whereas the Hoffmann (H) reflex remained unchanged: the T/H ratio was thus reduced. Hmax /M (direct motor)max ratio and the vibration-induced suppression of the T- and H-reflexes were unchanged. These findings indicate an effect of progabide on the spindles or on the controlling fusimotor system (probably acting on spinal interneurons), whereas influence on presynaptic inhibition and alpha-motoneuron excitability is unlikely. The flexor reflex threshold was increased during progabide treatment and latency at threshold decreased towards normal latency. This indicates some influence of progabide on flexor reflex activity attributed to reinforcement of action of GABAergic interneurons at the spinal level. Isokinetic measurement of voluntary power of knee extension revealed particularly good progress for the fastest movements during progabide treatment, whereas isometric measurement of sustained handgrip remained unchanged, probably reflecting a reduction of spasticity without reduction of voluntary power in non-spastic muscles.
D000125:Achilles Tendon / Q000294:innervation; D000328:Adult; D002986:Clinical Trials as Topic; D004576:Electromyography; D005260:Female; D006181:H-Reflex / Q000187:drug effects*; D006225:Hand / Q000294:innervation; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects*; D007866:Leg / Q000294:innervation; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects*; D009128:Muscle Spasticity / Q000188:drug therapy* / Q000503:physiopathology; D009132:Muscles / Q000294:innervation; D010919:Placebos; D012023:Reflex, Monosynaptic / Q000187:drug effects*; D012026:Reflex, Stretch / Q000187:drug effects*; D013979:Tibial Nerve / Q000503:physiopathology; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use
D010919:Placebos; C017985:progabide; D005680:gamma-Aminobutyric Acid