Efficacy and Safety Study of Z160 in Subjects With Postherpetic Neuralgia

A Phase 2, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study to Evaluate the Efficacy and Safety of Z160 in Subjects With Postherpetic Neuralgia

This study will compare Z160 and placebo in patients with Postherpetic Neuralgia for safety and efficacy for a period of 6 weeks.

Inclusion Criteria:

• Provide written informed consent.
• Either sex but must be aged >=18 years.
• Diagnosis of PHN as defined by the presence of pain in the area affected by herpes zoster >=6 months after the herpes zoster skin rash has healed.
• Pain score over the last week of >=3 and <=8 on the PI-NRS
• If female, the subject must be postmenopausal , surgically sterilized for >=3 months before the screening visit, or agree to use 2 reliable methods of contraception if of childbearing potential. If male, the subject must agree to use condoms.
• Willing and able to comply with all study procedures.

Exclusion Criteria:

• Severe pain caused by diseases other than PHN.
• Neurolytic or neurosurgical therapy for PHN within 6 months of screening (subjects who received a spinal cord stimulator implant at least 6 months before screening are eligible, but the settings need to remain stable during the double blind study period without use of a magnet).
• History of seizure, excluding pediatric febrile seizures, or currently has seizures.
• Stroke or transient ischemic attack (TIA) <=6 months before the screening visit.
• History of or a current diagnosis of schizophrenia or bipolar disorder.
• Major depressive disorder or generalized anxiety disorder <=6 months before the screening visit. Subjects who are on stable doses of selective serotonin uptake inhibitors (SSRIs) for depression (other than major depressive disorder) are eligible for the study.
• Clinically significant alcohol or substance dependency <=1 year before the screening visit
• Imminent risk of suicide (positive response to question 4 or 5 on the C-SSRS) or had a suicide attempt within 6 months before the screening visit.
• Clinically significant conditions that, in the investigator's opinion, may interfere with the study procedures or compromise the subject's safety.
• Malignancy (other than nonmetastatic basal or squamous cell carcinoma of the skin or carcinoma in situ of other organs that was surgically removed >1 year before screening and has not recurred).
• Condition that is known to interfere with the absorption, distribution, metabolism, or excretion of drugs.
• Illness within 30 days before screening.
• History of hypersensitivity to calcium channel blockers.
• Multiple drug allergies
• Opioids (at doses exceeding the equivalent of 15 mg of oral morphine) or a high-dose capsaicin patch (Qutenza) <=30 days before the screening visit.
• Moderate or strong cytochrome P450 inducer within 30 days before the screening visit.
• Digoxin or prohibited medications that cannot be discontinued before randomization.
• Other exclusions apply.