Please select the eligibility criteria that correspond to the clinical trial below.
Title: Study PXN110527: The Investigation of the Efficacy and Pharmacokinetics of XP13512 in Subjects With Neuropathic Pain Associated With Post-herpetic Neuralgia (PHN) Who Have Had an Inadequate Response to Gabapentin Treatment.
Brief Summary: The purpose of this study is evaluate the difference between two doses of gabapentin enacarbil (XP13512/GSK1838262), hereafter referred to as GEn, on pain associated with post-herpetic 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:

* 18 years or older
* Documented medical diagnosis of PHN with pain present for at least 3 months from the healing of a herpes zoster rash
* Female subjects are eligible if of non-childbearing potential or not lactating, has a negative pregnancy, and agrees to use one a specified highly effective method for avoiding pregnancy.
* Currently on a stable dose of 1800 mg/day of gabapentin for ≥2 weeks with inadequate response OR
* Not currently treated with gabapentin, but previously treated with ≥1800 mg/day of gabapentin for 4 weeks or more with inadequate response.
* Baseline 24-hour average pain intensity score ≥ 4.0 based on an 11-point PI-NRS
* Provides written informed consent in accordance with all applicable regulatory requirements

Exclusion Criteria:

* Other chronic pain conditions not associated with PHN. However, the subject will not be excluded if:
* The pain is located at a different region of the body; and
* The pain intensity is not greater than the pain intensity of the PHN; and
* The subject can assess PHN pain independently of other 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 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 drugs
* Medical condition or disorder that would interfere with the action, absorption, distribution, metabolism, or excretion of GEn, or, in the investigator's judgment
* Is considered to be clinically significant and may 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
* Current or chronic history of liver disease (including acute viral hepatitis), or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones).
* 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 meet entry criteria and must be stable for at least three months prior to enrollment
* History of clinically significant drug or alcohol abuse (DSM-IV-TR) or is unable to refrain from substance abuse throughout the study. 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 PHN, or
* Within preceding six months for studies related to PHN
* Treated previously with GEn
* History of allergic or medically significant adverse reaction to investigational products (including gabapentin) or their excipients, acetaminophen or related compounds
C: Inclusion Criteria:

* Confirmed diagnosis of acute HZ
* Pain intensity \> 30 mm visual analog scale

Exclusion Criteria:

* Patients with insulin-dependent diabetes mellitus or other diseases influencing the peripheral sensibility (e.g., polyneuropathia, chronic pain syndromes, cutaneous irritations i.e. burns)
* Patients under age
* Uncompliance
* Pregnancy or lactation
* Surgery within the last 3 month
* Severe heart/lung/kidney disease
* Diseases influencing the quality of life
* Psychiatric diseases (e.g., depression, schizophrenia, dementia)
* Chronic intake of analgesics, neuroleptics, antidepressants, corticoids, alpha-agonists
* Acupuncture, transdermal electric neurostimulation or other Complementary and Alternative Medicine treatment within the last 4 weeks
* Contraindications according to the summary of product informations against analgesic treatment (i.e., metamizol, paracetamol, tramadol, morphine) or the investigational medicinal products (gabapentine, acupuncture needles)
D: Inclusion Criteria:

* Chronic pain below the neck present for a minimum of one year.
* Diagnosis of at least one of the following:

  * back pain with or without leg pain,
  * post-herpetic neuralgia,
  * complex regional pain syndrome (CRPS) 1 or 2,
  * diabetic neuropathy,
  * or a general neuropathic condition; medically stable and able to undergo surgery for implantation of the drug infusion system.

Answer: B