Safety and Efficacy of Gabapentin in Diabetic Peripheral Neuropathy
A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study of the Safety and Efficacy of Gabapentin Extended Release (G-ER) Tablets in the Treatment of Patients With Painful Diabetic Peripheral Neuropathy
The purpose of this study is to determine whether a new Gabapentin tablet, is safe and effective for the treatment of painful diabetic peripheral neuropathy.
Inclusion Criteria: Men or women 18 years or older with diagnosis of type 1 or type 2 diabetes who have reported symmetrical painful symptoms in distal extremities for 1-5 years prior to the study and whose symptoms are attributable to sensorimotor diabetic peripheral neuropathy (DPN). Patients of childbearing potential must have a negative urine pregnancy test at screening/randomization, and must use medically acceptable methods of birth control. Patient has pain score of at least 4 on the 11-point Likert numerical rating scale at screening. Potential patients should not be informed of the pain intensity eligibility criterion prior to screening or randomization. Patient has a mean baseline week pain intensity of at least 4 on the 11-point Likert scale at the end of a one-week pre-treatment period and has completed at least 4 days of diary entries during the baseline week. Patient is on stable regimen of antidiabetes medication at screening that can be maintained during the study. Patient has hemoglobin A1c (HbA1c) ≤11% at screening. Patient has FPG ≤310 mg/dL at screening. Patient must have a minimum washout of greater than 5 times the half-life of the drug of any of several medications Patients currently treated with gabapentin or pregabalin at screening may be eligible for the study, but must have tapering period wherein the dose of gabapentin is reduced gradually over a period of at least 7 days plus a 2-day or 3-day washout of gabapentin or pregabalin, respectively, prior to start of the Baseline Week. Patient must have adequate eyesight to complete questions on the DiaryPro and SitePro. If a patient is unable to do so (for reasons other than severe eye disease) but a caregiver is available to complete these tasks following instruction from the patient, the caregiver may be trained to accomplish these tasks Exclusion Criteria: Patients who have previously not responded to treatment for DPN with gabapentin at doses of ≥1200 mg/day or pregabalin at doses ≥300 mg/day. Patients who previously experienced dose-limiting adverse effects that prevented titration of gabapentin to an effective dose. Patient has hypersensitivity to gabapentin. Patient is a nursing mother. Patient has used injected anesthetics or steroids within 30 days of baseline. Patient has certain conditions that could confound evaluation of painful DPN, in particular, amputations other than toes, non-diabetic neurologic disorders (e.g. phantom limb pain), and skin conditions affecting sensation in painful limbs. Patient has skin conditions in the area affected by the neuropathy that could alter sensation. Patient is in an immunocompromised state. Patient has an estimated creatinine clearance of <60 ml/min calculated using the Cockroft Gault method (Appendix 3). Patient has had malignancy within past 2 years other than basal cell carcinoma. Patient has had gastric reduction surgery. Patient has severe chronic diarrhea, chronic constipation [unless attributed to drugs that will be washed out], uncontrolled irritable bowel syndrome (IBS) or unexplained weight loss. Patient has any abnormal chemistry or hematology results that are deemed by the investigator to be clinically significant. Patient has a history of substance abuse within the past year. Patient has had 1 or more visits to an emergency room or hospital within the previous 30 days due to hypoglycemia. Patient has a history of seizure (except for infantile febrile seizure) or is at risk of seizure due to head trauma. Patient has a history of pernicious anemia, untreated hypothyroidism, chronic hepatitis B or C, hepatitis within the past 3 months, or HIV infection. Patient has any other serious medical condition that, in the opinion of the Investigator would jeopardize the safety of the patient or affect the validity of the study results. Continuing use of any concomitant medication excluded by Inclusion Criterion 8. Patient has participated in a clinical trial of an investigational drug or device within 30 days of the screening visit