Table 7.
Schematic overview of studies involving tramadol in human experimental pain models
| Reference | Dose | Model | Main findings | |
|---|---|---|---|---|
| Acute models | [117] (n= 15) | 50 mg orally. three times daily for 3 days | Ischaemic pain performance and PTT | No parameters were affected. |
| [111] (n= 27) | 100 mg iv | Nociceptive reflex to electrical sural nerve stimulation (single and repeated) PDT, PTT Cold pressor test peak pain, discomfort (VAS) | Extensive metabolizers: Nociceptive reflexes and pain thresholds ↔ Cold pressor test: discomfort ↓, peak pain ↔ Poor metabolizers: Single stimulation PTT (single electrical) ↓ Cold pressor test: discomfort ↓ | |
| [114] (n= 12) | 50 mg orally | Electrical tooth pulp stimulation sensation threshold, subjective pain rating, evoked brain potentials | No parameters were affected | |
| [113] (n= 20) | 100 and 200 mg sustained release orally | Stimulation of nasal mucosa by CO2 and dry air (tonic pain) VAS, evoked brain potentials (to CO2 stimulation) EEG (frequency analysis) | VAS to tonic pain ↓ VAS to CO2 stimulation ↔ Amplitudes of evoked potentials ↓ Latencies of evoked potentials ↔ EEG frequency spectrum was changed | |
| [121] (n= 27) | 2 mg kg−1 orally | Pressure algometry PDT, PTT (phalanx) Nocicpetive reflex to electrical sural nerve stimulation (single and repeated) stimulus response curve to electrical stimulation Cold pressor test AUCVAS peak pain, discomfort (VAS) | Extensive metabolizers: Pressure PDT and PTT ↑ Thresholds to nociceptive reflex ↑, stimulus response curve ↔ Cold pressor test: peak pain and AUCVAS↓, discomfort ↔ Poor metabolizers: Only significant effect on pressure PTT and single nociceptive reflex | |
| [112] (n= 16) | 150 mg orally | Stimulation of nasal mucosa by CO2VAS, evoked brain potentials (to CO2 stimulation), EEG (frequency analysis) | VAS and amplitudes of evoked potentials ↓ Latencies of evoked potentials ↔ EEG frequency spectrum ↔ | |
| [116] (n= 10) | 50 and 100 mg orally | Electrical tooth pulp stimulation sensation threshold, subjective pain rating, evoked brain potentials | All parameters were affected (dose-response manner) | |
| Models inducing hyperalgesia | [118] (n= 17) | 75 mg orally | Continuous electrical skin stimulation Ongoing pain (numeric rating scale) Area of secondary HA to pinprick (von Frey) | Ongoing pain ↓ Area of HA ↔ |
| [117] (n= 15) | 50 mg three times daily for 3 days | Delayed onset muscle sorenss Pressure algometry PDT (thigh, knee joint) | No parameters were affected |
In the column ‘model’ the method for pain assessment is normal font, and the method for pain induction is bolded. Abbreviations: pain detection threshold (PDT), pain tolerance threshold (PTT), area under curve (AUC), visual analogue scale score (VAS), hyperalgesia (HA).