Extended-release Pregabalin for the Treatment of Neuropathic Pain in Patients With Diabetic Peripheral Neuropathy and Postherpetic Neuralgia
Participants of either sex, aged 18 to 75 years.
Be able to understand and agree to participate in the study, undergo the procedures, and attend the visits, as indicated by signing the informed consent form approved by the CEP/Conep System.
diabetes mellitus (type 1 or 2), with glycated hemoglobin (HbA1c) levels ≤ 11%, documented symptoms of peripheral diabetic neuropathy for at least 6 months, and use of medication for glycemic control at a stable dose for at least 30 days.
postherpetic neuralgia, with pain symptoms for at least 3 months following a skin rash due to an acute episode of herpes zoster.
The presence of pain unrelated to the primary diagnosis of diabetic peripheral neuropathy or postherpetic neuralgia that could interfere with the evaluation.
Any skin condition that potentially alters sensation in the affected dermatome or area of neuropathic involvement, which could interfere with the assessment.
Having undergone neurosurgical therapy for the treatment of neuropathy.
Current use, or use within the past 7 days, of nerve block therapy and/or medications commonly used to treat neuropathic pain (e.g., benzodiazepines, skeletal muscle relaxants, capsaicin, local anesthetics, opioids, memantine), antiepileptic drugs (e.g., carbamazepine, clonazepam, phenytoin, valproic acid, lamotrigine, topiramate, gabapentin), antidepressants (e.g., tricyclics, serotonin reuptake inhibitors, venlafaxine), and potential neurotoxins (e.g., hydroxychloroquine, deferoxamine, thioridazine, vigabatrin).
Parallel
Experimental: Pregabalin XR
DrugPregabalin XR: extended-release tablet, with an initial dose of 82.5 mg once daily. The dose may be adjusted every 7 days during the first 4 weeks of treatment, up to a maximum of 660 mg once daily. In addition, the experimental group will receive a placebo twice daily.
Comparator: Dorene Tabs
DrugPregabalin immediate-release tablets, at an initial dose of 75 mg twice daily. The dose may be adjusted every 7 days during the first 4 weeks of treatment, up to a maximum of 300 mg twice daily. In addition, the comparator group will receive a placebo once daily.
Comparator placebo
DrugComparator placebo
experimental placebo
Drugexperimental placebo
Difference in the mean pain intensity score 16 weeks after the start of treatment, compared to baseline
Difference in the mean pain intensity score 16 weeks after the start of treatment, compared to baseline, between the study drug and the comparator, as measured by the 11-point DPRS (Daily Pain Rating Scale) (ranging from 0 "no pain" to 10 "worst possible pain"). Participants completed the baseline scale at the research center and filled it out daily at home until visit V8, twice a day. The average number of scales will be calculated by dividing the number of scales completed by the number of days on which they were completed.
To assess improvement in neuropathic pain during treatment.
Difference in the mean pain intensity score at 1, 4, 8, and 12 weeks after the start of treatment, compared to baseline, between the experimental drug and the comparator, as measured by the 11-point DPRS scale.
To assess the proportion of participants who experienced significant improvement in neuropathic pain during and at the end of treatment.
Difference in the mean total pain score at 1, 4, 8, 12, and 16 weeks after the start of treatment, compared to baseline, between the experimental drug and the comparator, as measured by the SF-MPQ (Short Form - McGill Pain Questionnaire).
To assess improvements in the impact of neuropathic pain on sleep, quality of life, and symptoms of anxiety and depression during and at the end of treatment.
Proportion of participants with a ≥ 30% reduction in pain intensity at 1, 4, 8, 12, and 16 weeks after the start of treatment, compared to baseline, between the study drug and the comparator, as measured by the 11-point DPRS scale. Difference in the mean score for pain interference with sleep at 4, 8, 12, and 16 weeks after the start of treatment, relative to baseline, between the study drug and the comparator, as measured by the 11-point DSIS (Daily Sleep Interference Scale) (ranging from 0 "pain did not interfere with sleep" to 10 "pain completely interfered with sleep"). Difference in quality of life at 4, 8, 12, and 16 weeks after the start of treatment, compared to baseline, between the experimental drug and the comparator, as measured by the WHOQoL-BREF (World Health Organization Quality of Life Scale). Difference in anxiety and depression symptoms at 4, 8, 12, and 16 weeks after the start of treatment, compared to baseline, between the experimental drug and the comparator.
Assess the participant's overall perception of change at the end of treatment.
Proportion of participants who rated their clinical condition as "much better," "moderately better," "slightly better," "no change," "slightly worse," "moderately worse," and "much worse," using the PGIC (Patient Global Impression of Change) scale, when comparing the experimental drug to the comparator 16 weeks after the start of treatment.
Safety Outcome: To evaluate the safety of extended-release pregabalin tablets compared with immediate-release pregabalin tablets in participants with diabetic neuropathy or postherpetic neuralgia.
Incidence rate of serious and non-serious adverse events-both related and unrelated-by treatment group throughout the clinical trial, based on an analysis of data obtained from clinical and physical examinations and laboratory tests.
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