Phase IIIb confirmatory study of efficacy and safety, longitudinal, multicenter, randomized, double-blind study of the combination Pregabalin/Tramadol versus Pregabalin in the management of acute pain of neuropathic origin.

Study to evaluate the efficacy and safety of the fixed-dose combination of Pregabalin/Tramadol versus Pregabalin in the management of acute pain of neuropathic origin. Patients who meet the inclusion criteria of the protocol and start treatment with the combination Pregabalin / Tramadol (75 mg / 50 mg) or Pregabalin 75 mg will be included. To evaluate the proportion of subjects who reported a success rate in the reduction of pain by 50%, the percentage of change in the pain intensity reported through the Visual Analog Pain Scale (VAS) will be calculated. This percentage will be categorized and the proportion of patients per treatment group will quantify. Changes in pain intensity during the intervention will be evaluated with the fixed-dose combination of Pregabalin/Tramadol (75 mg / 50 mg) or Pregabalin 75 mg, comparing the average difference in pain reported through VAS at days 1, 3, 5, 7, 10, 13 and 15 with respect to their baseline measurement. The mean change in reported neuropathic pain intensity across the DN4 questionnaire will also be evaluated, comparing its measurement on day 3, 10 and 15 with respect to the baseline, in each treatment group.

At visit 1 (day 3) the need for dose escalation will be evaluated (Pregabalin/Tramadol (150 mg / 50 mg) or pregabalin (150 mg)) in both treatment groups, continuing with its follow-up in the evaluation of the intensity of pain reported by EVA and DN4. The proportion of subjects who started on the dose of Pregabalin / Tramadol (75 mg / 50 mg) or Pregabalin 75 mg, those that required adjustment of dose to treatment (Pregabalin / Tramadol (150 mg / 50 mg) or Pregabalin (75 mg)), as well as the proportion of patients who suspended the treatment.

The percentage of adherence to the intervention by treatment group will be reported.

The proportion of adverse events presented during the conduct of the study will be evaluated, regardless of the dose administered, to all the subjects who have received at least one dose of the investigational drug Which will be reported be reported through frequencies and percentages and classified according to frequency, gravity, severity (intensity) and the causality of the clinical manifestation.

Inclusion Criteria:

• Any gender.
• That the subject agrees to participate in the study and give its informed consent in writing.
• Age >18 years and ≤65 years of age at the start of the study.
• Neuropathic Pain Questionnaire (DN4) ≥ 4.
• Patients with proven tolerability (absence of moderate-serious adverse events) to pregabalin, defined by consumption of pregabalin 50 mg/day for 3 days.
• Women of childbearing age who have an acceptable method of contraception (eg barrier, oral hormonal, injectable, subdermal).

Exclusion Criteria:

• Contraindication and known hypersensitivity to the use of pregabalin and/or tramadol.
• The patient is participating in another clinical study involving an investigational treatment or participated in any in the previous 4 weeks.
• In the medical opinion, a disease that affects the prognosis and prevents outpatient management, for example, but not limited or restricted to: terminal cancer, heart failure, obstruction gastrointestinal including paralytic ileus, suspected surgical abdomen, respiratory failure with scheduled surgical or hospital procedures.
• Positive pregnancy test, women who are pregnant, nursing or planning a pregnancy during the conduct of the study.
• Patients with a diagnosis of respiratory diseases: status asthmaticus, asthma, chronic obstructive pulmonary disease (COPD), cor pulmonale, acute respiratory depression, hypercapnia.
• Patients who are receiving monoamine oxidase inhibitors (MAOIs) or who have received within the last 2 weeks.
• Patients with a history of seizure disorders, epileptic status, and grand mal seizures.
• Patients with a history of severe depression of the central nervous system due to consumption of opiates.
• History of acute intoxications with hypnotics, opioid analgesics and psychotropics.
• History of alcohol or drug abuse (including opiates) in the last year according to DSM-V.
• Patients with a history of severe head trauma and/or brain edema.
• History/presence of any disease or condition which, in the opinion of the Investigator, could pose a risk to the patient or confound the efficacy and safety results of the study.
• Patients with symptoms suggestive of active COVID-19 infection (i.e., fever, cough, dyspnea) and/or contact in the last 14 days with a suspected or positive patient for COVID-19.
• Patients whose participation in the study may be influenced (employment relationship with the center investigator or sponsor, inmates, etc.).