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Updated: Jan 31, 2026
Subcutaneous Trigeminal Nerve Field Stimulation for Refractory Facial Pain
Published on: May 10, 2017
Challenges recruiting to a proof-of-concept pharmaceutical trial for a rare disease: the trigeminal neuralgia
Joanna M Zakrzewska1,2,3, Joanne Palmer4, Lars Bendtsen5
1Facial Pain Unit, Division of Diagnostic, Surgical and Medical Sciences, Eastman Dental Hospital, University College London Hospitals NHS Foundation Trust/University College London, London, UK. j.Zakrzewska@ucl.ac.uk.
Background:
This study aimed to describe recruitment challenges encountered during a phase IIa study of vixotrigine, a state and use-dependent Nav1.7 channel blocker, in individuals with trigeminal neuralgia.
Methods:
This was an international, multicenter, placebo-controlled, randomized withdrawal study that included a 7-day run-in period, a 21-day open-label phase, and a 28-day double-blind phase in which patients (planned n = 30) were randomized to vixotrigine or placebo. Before recruitment, all antiepileptic drugs had to be stopped, except for gabapentin or pregabalin. After the trial, patients returned to their original medications. Patient recruitment was expanded beyond the original five planned (core) centers in order to meet target enrollment (total recruiting sites N = 25). Core sites contributed data related to patient identification for study participation (prescreening data). Data related to screening failures and study withdrawal were also analyzed using descriptive statistics.
Results:
Approximately half (322/636; 50.6%) of the patients who were prescreened at core sites were considered eligible for the study and 56/322 (17.4%) were screened. Of those considered eligible, 26/322 (8.1%) enrolled in the study and 6/322 (1.9%) completed the study. In total, 125 patients were screened across all study sites and 67/125 (53.6%) were enrolled. At prescreening, reasons for noneligibility varied by site and were most commonly diagnosis change (78/314; 24.8%), age > 80 years (75/314; 23.9%), language/distance/mobility (61/314; 19.4%), and noncardiac medical problems (53/314; 16.9%). At screening, frequently cited reasons for noneligibility included failure based on electrocardiogram, insufficient pain, and diagnosis change.
Conclusions:
Factors contributing to recruitment challenges encountered in this study included diagnosis changes, anxiety over treatment changes, and issues relating to distance, language, and mobility. Wherever possible, future studies should be designed to address these challenges.
Trial Registration:
ClinicalTrials.gov, NCT01540630 . EudraCT, 2010-023963-16. 07 Aug 2015.
Insights
Recruiting for trigeminal neuralgia studies is challenging due to diagnosis changes and patient-related issues. Addressing these factors is crucial for future clinical trial success.
Area of Science:
- Neurology
- Clinical Pharmacology
Background:
- A phase IIa study investigated vixotrigine, a Nav1.7 channel blocker, for trigeminal neuralgia.
- Recruitment challenges were identified during this international, multicenter trial.
Purpose of the Study:
- To describe the recruitment challenges encountered during a phase IIa study of vixotrigine in trigeminal neuralgia patients.
- To analyze factors contributing to patient eligibility, screening, and enrollment.
Main Methods:
- International, multicenter, placebo-controlled, randomized withdrawal study design.
- Inclusion criteria required discontinuation of most antiepileptic drugs, allowing gabapentin or pregabalin.
- Descriptive statistics were used to analyze prescreening, screening, and withdrawal data.
Main Results:
- Over 50% of prescreened patients were eligible, but only 17.4% were screened and 8.1% enrolled at core sites.
- Across all sites, 125 patients were screened, with 53.6% enrolling.
- Key reasons for noneligibility included diagnosis changes, age, language/distance/mobility issues, and medical comorbidities.
Conclusions:
- Recruitment was hampered by diagnosis changes, patient anxiety regarding medication adjustments, and logistical barriers (distance, language, mobility).
- Future study designs should proactively address these identified recruitment challenges to improve enrollment and trial efficiency.
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