Table 5.
Schematic overview of studies involving gabapentin in human experimental pain models
| Reference | Dose | Model | Main findings | |
|---|---|---|---|---|
| Acute models | [69] (n= 12) | 1800 mg p.o. | Repeated pinprick stimulation of the skin VAS, fMRI | VAS, fMRI was modulated |
| [68] (n= 25) | 1200 mg p.o. | Heat skin stimulation (1 °C s−1) PDT, pain intensity (VAS) after long-lasting heat stimulation | Heat PDT ↔ VAS after long-lasting heat stimulation ↔ | |
| [25] (n= 12) | 600 mg p.o. | Cold pressor test AUCVAS | AUCVAS↔ | |
| [71] (n= 16) | 1200 as single dose or 2600 as multiple doses mg p.o. | Intramuscular infusion of hypertonic saline peak pain (VAS), AUCVASPDT to repetitive pinprick stimulation | AUCVAS, peak VAS ↔ PDT ↔ | |
| [70] (n= 20) | 1200 mg p.o. | Single and repeated cutaneous and intramuscular electrical stimulation PDT, stimulus response curve Intramuscular injection of hypertonic saline AUCVAS, area of referred pain | Single and repeated electrical stimulation: –cutaneous PDT ↑ –muscle PDT ↔ Stimulus response curve ↔ Injection of hypertonic saline: AUCVAS and area of referred pain ↓ | |
| Models inducing hyperalgesia | [73] (n= 41) | 2400 mg p.o. daily (15 days of dosing) | Intradermal injection of capsaicin spontaneous pain rated (VAS) area of HA to pinprick, allodynia to brushing, intensity of pain to pinprick and brushing | Area of allodynia to brushing ↓ Spontaneous pain, area of HA to pinprick, brush and pinprick pain ↔ |
| [68] (n= 25) | 1200 mg p.o. | Heat-capsaicin sensitization In primary HA area: PDT to heat Area of secondary HA to pinprick and allodynia to brushing | Heat PDT ↑ Area of HA to pinprick and allodynia ↓ | |
| [69] (n= 12) | 1800 mg p.o. | Heat-capsaicin sensitization, spontaneous pain (VAS), fMRI, HA to repeated pinprick stimulation | Spontaneous pain ↔ fMRI: small decrease of pain/hyperalgesia induced deactivation of areas in the insula and somatosensory cortex | |
| [71] (n= 16) | 1200 as single dose or 2600 as multiple doses mg p.o. | Continuous intracutaneous electrical stimulation threshold of moderate pain, ongoing pain (VAS), area of secondary HA to pinprick, PDT to repetitive pinprick stimulation in HA area | Threshold to moderate pain↑, but only for 2600 mg Ongoing pain and PDT to repetitive pinprick ↔ (both doses) Area of HA to pinprick ↓ | |
| [74] (n= 16) | 600 mg p.o. | Burn injury (UVB) PDT and PTT to heat in the primary HA area and in control area, area of secondary HA to pinprick | Primary HA area: heat PDT ↔, PTT ↑ Control area: heat PDT and PTT ↔ Area of secondary HA to pinprick ↓ |
In the column ‘Model’ the method for pain assessment is normal font, and the method for pain induction is bold. PDT, pain detection threshold; PTT, pain tolerance threshold; AUC, area under curve; VAS, visual analogue scale; HA, hyperalgesia; fMRI, functional magnetic resonance imaging.