Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Phase 3 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 Postherpetic Neuralgia
Brief Summary: Gabapentin and pregabalin are treatments for some types of neuropathic pain, including postherpetic neuralgia (PHN). However, these treatments usually need to be taken 3 times a day for effective pain control. The purpose of this study is to determine whether a new gabapentin tablet, which only needs to be taken once or twice a day, is safe and effective for the treatment of postherpetic neuralgia.


Options:
A: Inclusion Criteria:

1. Men or women 18 years or older who have experienced pain for at least 3 months after the healing of a herpes zoster skin rash (typically about 4 months after the rash first appears).
2. Patient has pain intensity 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.
3. Patients of childbearing potential must have a negative urine pregnancy test at screening/randomization, and must use medically acceptable methods of birth control. Acceptable methods of birth control include oral or transdermal contraceptives, condom, spermicidal foam, intrauterine device (IUD), progestin implant or injection, abstinence, vaginal ring, or sterilization of partner. The reason for non-childbearing potential, such as bilateral tubal ligation, bilateral oophorectomy, hysterectomy, or postmenopausal for ≥ 1 year, must be specified in the patient's case report form (CRF).
4. Patient has a mean baseline week pain intensity score of at least 4 on the 11-point Likert scale at the end of a 1-week pre-treatment period and has completed at least 4 days of daily pain diary entries during the baseline week.
5. Patient must have a minimum washout period of greater than 5 times the half-life of the drug of any of the following medications: benzodiazepines, skeletal muscle relaxants, orally administered steroids, capsaicin, mexiletene, centrally acting analgesics (dextromethorphan, tramadol), opiates, topical lidocaine, anticonvulsants and serotonin and norepinephrine reuptake inhibitors (SNRIs). Anticonvulsants, SNRIs, opiates and benzodiazepines should be tapered appropriately, using product label instructions as a guide.
6. Patients currently treated with gabapentin or pregabalin at screening may be eligible for the study, but must have a tapering period wherein the dose of gabapentin or pregabalin 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.

Exclusion Criteria:

1. Patients who have previously not responded to treatment for PHN with gabapentin at doses of ≥ 1200 mg/day or pregabalin at doses ≥ 300 mg/day.
2. Patients who previously experienced dose-limiting adverse effects that prevented titration of gabapentin to an effective dose.
3. Patient is a nursing mother.
4. Patient has hypersensitivity to gabapentin.
5. Patient has had neurolytic or neurosurgical treatment for PHN.
6. Patient has severe pain from causes other than PHN.
7. Patient has used injected anesthetics or steroids within 30 days of baseline.
8. Patient has skin conditions in the area affected by the neuropathy that could alter sensation.
9. Patient is in an immunocompromised state.
10. Patient has an estimated creatinine clearance of \< 60 ml/min calculated using the Cockroft Gault method. If the patient fails this criterion, the Investigator may decide to conduct a 24-hour creatinine clearance test. The patient would be allowed to enroll in the study if the 24-hour test result is \< 60 ml/min.
11. Patient has had a malignancy within the past 2 years other than basal cell carcinoma.
12. Patient has had gastric reduction surgery.
13. 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.
14. Patient has any abnormal chemistry or hematology results that are deemed by the Investigator to be clinically significant.
15. Patient has a history of substance abuse within the past year.
16. Patient has a history of seizure (except for infantile febrile seizure) or is at risk of seizure due to head trauma.
17. Patient has a history of chronic hepatitis B or C, hepatitis within the past 3 months, or HIV infection.
B: 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
C: Inclusion criteria:

* 18 years or older
* Female subjects are eligible to enter if of non-childbearing potential or not lactating, has a negative pregnancy test and agrees to use a specified highly effective method for avoiding pregnancy
* Documented medical diagnosis of Type 1 or 2 diabetes including:
* Stable glycemic control for 3 months defined as \<25% change of routine insulin, \<50% change of routine oral anti-diabetic agent dose and HbA1c \< 8%. (HbA1c of 8 to 11% eligible if attempts to improve diabetic control failed)
* DPN defined by:
* Bilateral reduced or absent reflexes at the ankles, or
* Bilateral impaired vibration, pinprick, fine touch or temperature perception in the distal lower extremities And
* Persistent distal burning or dull pain in the feet, or
* Persistent proximal aching pain in the legs, or
* Paroxysmal electric, shooting, stabbing pain, or
* Dysasthesias, or
* Evoked pain And
* history of pain for at least six months and no greater than five years attributed to DPN (refers to duration of pain)
* Baseline 24-hour average daily pain intensity score \>4.0 as measured on an 11 point pain intensity numerical rating scale
* Provides written informed consent in accordance with all applicable regulatory requirements

Exclusion criteria:

* Other chronic pain conditions not associated with DPN. However, the subject will not be excluded if:
* The pain condition is located at a different region of the body, and
* The pain intensity of this condition is not greater than the pain intensity of the DPN, and
* The subject can assess their DPN independently of other pain condition.
* Other causes of neuropathy or lower extremity pain
* Is unable to discontinue prohibited medications or non-drug therapies or procedures throughout the duration of the study
* Hepatic impairment defined as ALT or AST \> 2x upper limit of normal (ULN) or alkaline phosphatase or bilirubin \> 1.5x ULN
* Chronic hepatitis B or C
* Impaired renal function defined as either creatinine clearance \< 60 mL/min or requiring hemodialysis
* Corrected QT (QTc) interval \>450 msec or QTc interval \>480 msec for patients with Bundle Branch Block
* Uncontrolled hypertension at screen (sitting systolic \>160 mmHg and/or sitting diastolic \>90 mmHg
* Current diagnosis of active epilepsy or any active seizure disorder requiring chronic therapy with antiepileptic drug(s)
* Medical condition or disorder that would interfere with the action, absorption, distribution, metabolism, or excretion of GEn or pregabalin, or, in the investigator's judgment:
* Is considered to be clinically significant and could pose a safety concern or,
* Could interfere with the accurate assessment of safety or efficacy, or,
* Could potentially affect a subject's safety or study outcome
* Meets criteria defined by the DSM-IV-TR for a major depressive episode or for active significant psychiatric disorders within last year
* Depression in remission, with or without antidepressant treatment, may participate, unless stable antidepressant regimen is a prohibited medication
* Antidepressant medication may not be changed or discontinued to met entry criteria and must be stable for at least 3 months prior to enrollment
* History of clinically significant drug or alcohol abuse (DSM-IV-TR). Benzodiazepines or atypical benzodiazepines as hypnotic sleep agents permitted
* Currently participating in another clinical study in which the subject is, or will be exposed to an investigational or non-investigational drug or device
* Has participated in a clinical study and was exposed to investigational or non-investigational drug or device:
* Within preceding month for studies unrelated to DPN, or
* Within six months for studies related to DPN
* Treated previously with GEn
* History of allergic or medically significant adverse reaction to investigational products (including gabapentin or pregabalin) or their excipients, acetaminophen or related compounds
D: Inclusion Criteria:

* You must have been diagnosed with Diabetic Neuropathic Pain
* Patient has an average daily pain score greater than or equal to 4 on an 11-point Likert scale, and patient or provider feel that a change from the current gabapentin therapy for pain management is warranted
* Patient is currently treated with gabapentin greater than or equal to 900 milligram/day, has been prescribed the current dose for at least 4 weeks, and has been at least 80% compliant with dosing, according to patient report
* Patient must agree not to change dose of gabapentin between Visits 1 and 2
* You must have stable glycemic control

Exclusion Criteria:

* Are judged prior to randomization to be at suicidal risk as defined by a score of 2 or greater on question 9 of the Beck Depression Inventory-II (BDI-II)
* Current diagnosis or history of hemangiosarcoma
* Patients with New York Heart Association Class III or IV symptoms of congestive heart failure
* Patients with uncontrolled narrow-angle glaucoma
* Presence of a current seizure disorder

Answer: A