Study: NCT01676246

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: 100 mg flupirtine per os
Description: Administration of 100 mg flupirtine per os (1 capsule Kadadolon®)

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: 400 mg flupirtine per os
Description: Administration of 400 mg flupirtine (1 Kadadolon® S long retard tablet)

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: induce delayed onset of muscle soreness (DOMS)
Description: The DOMS exercise protocol consists of two sets of 50 concentric/eccentric contractions of the calf muscles of one leg with a rest of 5 min in-between. The exercise is performed 22-26 h prior to medication. For pain measurements, muscle pain is stimulated by standing on tiptoes of one leg for 30 s, which requires a constriction of the affected calf muscles. The other leg is lifted and the subjects are allowed to hold on to a table to keep their balance. The pain intensity during this stimulation is then rated by means of a 10 cm visual analogue scale (VAS). The VAS is extended from no pain to intolerable pain with a precision of 1 mm. The stimulation is repeated with the other leg. The sequence of the legs is chosen randomly.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: induce delayed onset of muscle soreness (DOMS)
Description: The DOMS exercise protocol consists of two sets of 50 concentric/eccentric contractions of the calf muscles of one leg with a rest of 5 min in-between. The exercise is performed 22-26 h prior to medication. For pain measurements, muscle pain is stimulated by standing on tiptoes of one leg for 30 s, which requires a constriction of the affected calf muscles. The other leg is lifted and the subjects are allowed to hold on to a table to keep their balance. The pain intensity during this stimulation is then rated by means of a 10 cm visual analogue scale (VAS). The VAS is extended from no pain to intolerable pain with a precision of 1 mm. The stimulation is repeated with the other leg. The sequence of the legs is chosen randomly.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: electric pain measurement
Description: The method has been described to be sensitive to quantify analgesic opioid effects. Painful 5 Hz sine waves electrical stimuli (increase of intensity 0.2 mA/s, from 0 to 20 mA), which predominantly activate C-fibres, will be applied via two gold electrodes placed on the medial and lateral side of the distal phalangeal joint (middle finger of the left hand as default-testing site).~During testing, subjects keep a button continuously pressed until they find the pain intolerably and interrupt the current by releasing the button. The electrical current at which this occurred is defined as pain tolerance, the target parameter of this pain model. Each value of pain tolerance is the median of five subsequent measurements obtained at an interval of 1 min.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: electric pain measurement
Description: The method has been described to be sensitive to quantify analgesic opioid effects. Painful 5 Hz sine waves electrical stimuli (increase of intensity 0.2 mA/s, from 0 to 20 mA), which predominantly activate C-fibres, will be applied via two gold electrodes placed on the medial and lateral side of the distal phalangeal joint (middle finger of the left hand as default-testing site).~During testing, subjects keep a button continuously pressed until they find the pain intolerably and interrupt the current by releasing the button. The electrical current at which this occurred is defined as pain tolerance, the target parameter of this pain model. Each value of pain tolerance is the median of five subsequent measurements obtained at an interval of 1 min.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: electric pain measurement
Description: The method has been described to be sensitive to quantify analgesic opioid effects. Painful 5 Hz sine waves electrical stimuli (increase of intensity 0.2 mA/s, from 0 to 20 mA), which predominantly activate C-fibres, will be applied via two gold electrodes placed on the medial and lateral side of the distal phalangeal joint (middle finger of the left hand as default-testing site).~During testing, subjects keep a button continuously pressed until they find the pain intolerably and interrupt the current by releasing the button. The electrical current at which this occurred is defined as pain tolerance, the target parameter of this pain model. Each value of pain tolerance is the median of five subsequent measurements obtained at an interval of 1 min.