Effect of Gabapentin Enacarbil on Opioid Consumption and Pain Scores

Study Overview
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Brief Summary
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Opioids are effective analgesics, but cause side effects including sedation, respiratory depression, low blood pressure, nausea, and constipation. Gabapentin enacarbil, which is a FDA approved drug for post herpetic neuralgia (nerve pain related to shingles) and restless leg syndrome, may decrease your need for narcotics and thus decrease the risk of side effects. The investigator hopes this study will determine if gabapentin enacarbil decreases opioid consumption and pain after surgery. Patients having elective hip and knee surgery will be asked to participate in the study. Patients will be randomized to Gabapentin enacarbil 600mg twice per day for 5 days or Placebo twice per day for 5 days. One day prior to surgery the patient will take Gabapentin enacarbil 600mg or placebo 600mg twice a day with meals. On the day of surgery, the patient will take Gabapentin enacarbil 600mg or placebo 600mg two hours before the surgical procedure. Six hours after the completion of surgery, the patient will receive Gabapentin enacarbil 600mg or placebo 600mg. If the patient is sent home, the patient will be given 6 Gabapentin enacarbil 600mg or placebo 600mg pills to take home along with instructions. However, if the patient remains hospitalized, on the first day after the surgery, the patient will have pain assessed in the morning using a numerical rating score. The patient's quality of recovery will be evaluated using a questionnaire and the patient will receive Gabapentin enacarbil 600mg or placebo 600mg twice a day with meals. The second and third day the patient is in the hospital, the patient will have pain assessed in the morning using a numerical rating score and the patient will receive Gabapentin enacarbil 600mg or placebo 600mg twice a day with meals. Then, three months after surgery, the patient will receive a phone call to follow-up with possible pain or discomfort the patient may be feeling.

Official Title
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A Randomized Controlled Trial to Determine the Effect of Gabapentin Enacarbil on Opioid Consumption and Pain Scores in Patients Having Hip and Knee Arthroplasties With Spinal Anesthesia

Conditions
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Pain

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


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men or women 18-85 years of age. Scheduled for elective knee or hip arthroplasty with spinal anesthesia. Exclusion Criteria: Creatinine >1.50 mg/dl. History of clinically important current depression or currently on any prescribed anti-depressant medication. Previously enrolled in any Xenoport trial. Use of gabapentin or gabapentinoids (Lyrica, Horizant, Neurontin or Gralise) within one month. Allergy to gabapentin or gabapentinoids (Lyrica, Horizant, Neurontin or Gralise). Women who are pregnant or breastfeeding. History of seizure disorder within the last one-year or taking medications for seizures.

Ages Eligible for Study
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Minimum Age: 18 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 |
| --- | --- |
| Experimental: Gabapentin enacarbil<br>Patients going through elective hip or knee replacement surgery with spinal anesthesia will receive Gabapentin enacarbil for 5 days | Drug: Gabapentin enacarbil<br>* 600 mg BID 1 day pre-op and 2 hours before surgery, 6 hours after surgery, 600 mg BID 3 days post-operative<br>* Other names: Xenoport;|
| Placebo Comparator: Placebo<br>Patients going through elective hip or knee replacement surgery with spinal anesthesia will receive placebo for 5 days | Drug: Placebo<br>* 600 mg BID taken 1 day pre-op and 2 hours before surgery, 6 hours after surgery, 600 mg 3 days post-operative<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time weighted average pain score in numerical rating scores | Multiple pain measurements (numeric rating scale ranges from 0 to 10, where 0 - no pain and 10 - worse imaginable pain) over 72 hours after the surgery will be summarized by computing time weighted average pain score for each patient | 72 hours after surgery or till discharge, whatever comes first | 
| Cumulative postoperative opioid consumption | The total dose of opioid administered in the PACU and floor including the background analgesia (PCA) and boluses. All opioids will be converted into mg intravenous (IV) morphine equivalent to standardize opioid consumption . | 72 hours after surgery or till discharge, whatever comes first |