Effect of Pregabalin in Patients With Radiotherapy-related Neuropathic Pain

Effect of Pregabalin in Patients With Radiotherapy-Related Neuropathic Pain: a Randomized, Double-blind, Placebo-controlled Trial

Rationale: Pregabalin is effective on radiotherapy-related neuropathic pain. Purpose: This randomized, double-blind, placebo-controlled trial aims to investigate the effect and safety of pregabalin in treating radiotherapy-related neuropathic pain.

Radiotherapy for cancer is associated with peripheral neuropathies, especially with brachial plexus neuropathy and trigeminal neuralgia, which included painful sensation that are described as burning, aching, spasm, or tingling. Though there is some recommendation about neuropathic pain, there is no definite drug which is recommended for radiotherapy-related neuropathic pain.

Pregabalin, a central nervous system(CNS)-active compound, is an analog of the neurotransmitter gamma-aminobutyric acid. It has been proved an effective treatment for diabetic peripheral neuropathy and postherpetic neuralgia in previous clinical trials. This study plans to evaluate the efficacy of pregabalin versus placebo for relieving radiotherapy-related peripheral neuropathic pain, and assessed its safety.

Inclusion Criteria:

1. Patients must have received radiation therapy for histologically confirmed head and neck cancer.
2. Clinical evidence support the diagnosis of radiation-related neuropathic pain (confirmed by the Michigan Neuropathy Screening Instrument) and had a daily pain score of 4 or higher based on a numerical rating scale (0-10 points).
3. Neuropathic pain defined according to clinical history, symptoms, physical signs, and a score>= 12 in Chinese version of Leeds Assessment of Neuropathic Symptoms and Signs questionnaire by two neurology specialists.
4. The mean duration of pain is more than 4 weeks.
5. Fertile women who are willing to take contraception during the trial.
6. Routine laboratory studies with bilirubin </=2 * upper limits of normal (ULN), aspartate aminotransferase (AST or SGOT) < 2 * ULN, creatinine <1.0 * ULN, red-cell count >/= 4,000 per cubic millimeter; white-cell count >/=1500 per cubic millimeter, platelets >/= 75,000 per cubic millimeter; Hb >/=9.0.
7. Ability to understand and willingness to sign a written informed consent document.

Exclusion Criteria:

1. Current diagnosis of tumor recurrence or metastasis and evidence of tumor associated pain.
2. Evidence of secondary neuropathic pain other than radiation.
3. Treatment with carbamazepine, gabapentin or pregabalin within 30 days before study enrollment.
4. Ongoing treatment for neuropathic pain.
5. History of anaphylactic response to pregabalin.
6. Evidence of sever systematic diseases.