Analgesic Effect of Gabapentin in Total Knee Arthroplasty (TKA)

Study Overview
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Brief Summary
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Pain is a major problem after TKA. Gabapentin may reduce acute postoperative pain. The investigators therefore investigate the effect of Gabapentin as a perioperative analgesic.

Detailed Description
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Pain is a major problem after TKA. Studies indicate that Gabapentin may reduce acute postoperative pain. However, the optimal dose is unknown and there is constant controversy on analgesic versus side-effects. The investigators therefore investigate the effect of Gabapentin as a perioperative analgesic in a dose-related manner and with a sample-size allowing evaluation of side-effects.

Official Title
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Analgesic Effect of Perioperative Gabapentin in Total Knee Arthroplasty: A Randomized, Double-blind, Placebo-controlled, Dose-response Study

Conditions
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Postoperative Pain, Postoperative Sedation

Intervention / Treatment
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* Drug: Gabapentin
* Drug: Gabapentin
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Primary, unilateral total knee arthroplasty (TKA) Age 50-85 years Ethnic Danes Exclusion Criteria: Treatment with gabapentins, systemic glucocorticoids, opioids, anxiolytic agents, antiepileptics or antidepressive agents (last 4 weeks) History of depression or mania History of alcohol or drug abuse History of malignancy History of epilepsia BMI > 40 Disease affecting central or peripheral nerve function History of dementia History of renal insufficiency Allergy to Gabapentin Women with menstruation (last 2 years)

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Gabapentin high<br>Tables with Gabapentin (1300 mg/day) for 7 days, starting on the day of surgery | Drug: Gabapentin<br>* Tables with Gabapentin (1300 mg/ day) for 7 days, starting on the day of surgery<br>|
| Active Comparator: Gabapentin intermediate<br>Tables with Gabapentin for 7 days (900 mg/day), starting on the day of surgery | Drug: Gabapentin<br>* Tables with Gabapentin (900 mg/day) for 7 days, starting on the day of surgery<br>|
| Placebo Comparator: Placebo<br>Placebo tablets for 7 days, starting on the day of surgery | Drug: Placebo<br>* Placebo tablets for 7 days, starting on the day of surgery<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain | Pain during walking at 24 hour after surgery, visuel analog scale (VAS, 0-100 mm) | At 24 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sedation | Sedation at 6 hours, numeric range scale (NRS, 0-10) | At 6 hours | 
| Pain | Pain at rest and during walking the first week after TKA, visuel analog scale (VAS, 0-100 mm) | 1 week | 
| Cumulated pain scores | Cumulated pain scores for pain the first week after TKA | 1 week | 
| Amount of rescue analgesic | Amount of rescue analgesic the first week after TKA, mg | 1 week | 
| Side effects | Side effects the first week after TKA | 1 week | 
| Cumulated side effects scores | Cumulated side effects scores the first week after TKA | 1 week | 
| Amount of ondansetron and sleeping medicine | Amount of ondansetron and sleeping medicine the first week after TKA, mg | 1 week | 
| Anxiety and depression | Anxiety and depression - questionnaire - the first week after TKA, Hospitality and Anxiety and Depression Scale | 1 week | 
| Gabapentin level in blood-sample | Gabapentin level in blood-sample at 12 am on the first day after surgery, serum-koncentration | 1 Day |