dose response study of ema401 in patients with post-herpetic neuralgia (phn)

Conditions: Post-herpetic Neuralgia

Summary: this study was designed to characterize dose response, and evaluate safety and efficacy of three different doses of ema401 compared to placebo in patients with post-herpetic neuralgia (phn).

this was an interventional, randomized, parallel, placebo-controlled, dose ranging, double-blind treatment study consisting of 3 periods i.e. screening, treatment, and treatment withdrawal. the study was planned in two cohorts. the initial cohort had three treatment arms i.e. placebo b.i.d., ema401 25 mg b.i.d., or ema401 100 mg b.i.d. following an unblinded safety review by an independent dmc, the second cohort was to have been initiated with an additional treatment arm i.e. ema401 300 mg b.i.d.. due to the premature study termination, the second cohort was not initiated. at the end of treatment period the 25mg bid and 100mg bid arms were re-randomized (1:1) to the same treatment or placebo. placebo arm stayed on placebo. the planned duration of treatment period was 12 weeks and 1 week of treatment withdrawal at the end of treatment period. the study was terminated early due to pre-clinical toxicity data that became available after start of trial. novartis implemented a urgent safety measure (usm) which instructed sites to discontinue study treatment immediately and to have all patients return for additional laboratory assessments (full hematology including coagulation and clinical chemistry panel). safety data from the usm was presented as a separate outcome measure table and not included in the adverse event section.

Eligibility criteria:
inclusion criteria: * at the time of screening, must have had documented diagnosis of phn (icd-10 code b02.29), defined as pain in the region of the rash persisting for more than 6 months after onset of herpes zoster rash. * assessed as suffering from moderate to severe neuropathic pain across the screening epoch (nrs ≥ 4). * patients must have had documented past and/or ongoing inadequate treatment response (having insufficient pain relief with treatment or inability to tolerate) to at least 2 different prescribed therapies commonly used to treat and considered effective by the investigator for the treatment of phn. * patient must have been willing to complete daily ediary exclusion criteria: * history or had current diagnosis of electrocardiogram (ecg) abnormalities indicating significant risk of safety for patients participating in the study * had a major depressive episode within 6 months prior to screening and/or a history of diagnosed recurrent major depressive disorder according to diagnostic and statistical manual of mental disorders, 5th edition (dsm-v) diagnostic criteria * women of child-bearing potential, defined as all women physiologically capable of becoming pregnant. * had evidence of significant renal insufficiency or pre-existing liver condition * had platelets ≤ 100 x 10\^9/l, or neutrophil count \< 1.2 x 10\^9/l (or equivalent), hemoglobin ≤ 100 g/l for women or hemoglobin ≤ 110 g/l for men. * patients who had a known diagnosis of diabetes and are stable on medication with a hemoglobin a1c \> 8%. those who did not have a known diagnosis of diabetes with a hemoglobin a1c \> 7%.

Keywords: post-herpetic neuralgia neuropathic pain angiotensin ii type 2 receptor antagonist dose ranging