The Interaction Between Gabapentin and Amitriptyline in the Rat Formalin Test After Systemic Administration
Bibliographic record
Abstract
UNLABELLED: We examined the effects of systemically administered gabapentin on flinching and biting/licking behaviors produced by 2.5% formalin in the rat, compared these with those of amitriptyline, and determined the effects of combinations of gabapentin with amitriptyline. Gabapentin produced a dose-related inhibition of Phase 2, but not Phase 1, flinching and biting/licking behaviors. In contrast, amitriptyline produced an increase in Phase 2 flinching behaviors while simultaneously decreasing biting/licking behaviors. Fifty percent effective dose (ED50) values against biting/licking behaviors were 22.9 +/- 1.3 mg/kg and 8.5 +/- 1.3 mg/kg for gabapentin and amitriptyline, respectively. Combinations of increasing fractional increments of ED50 doses of gabapentin and amitriptyline produced an additive effect against biting/licking behaviors, as revealed by isobolographic analysis. These increments had no effect on flinching behaviors except at the ED25 + ED25 doses, at which flinching was increased, again revealing additivity between the two drugs. Flinching behaviors in rats do not reflect the analgesic properties of systemically administered amitriptyline observed in humans and may not be useful for predicting an effect of combinations of drugs with amitriptyline. Biting/licking behaviors do reflect analgesic properties for both drugs and may be more useful in this regard. IMPLICATIONS: By use of the rat formalin test, a model of persistent pain, we examined the effect of a combination of amitriptyline and gabapentin, which are used to treat chronic pain in humans. The drug combination produced additive analgesia against one outcome, but another outcome was more ambiguous.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".