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NCT Number: NCT05944510

Dextromethorphan as an Augmentation Agent in Treatment-resistant Schizophrenia

Dextromethorphan acts as N-methyl-D-aspartate (NMDA) antagonist. In Treatment resistant schizophrenia(TRS) the efficacy of treatment response by clozapine is only around 40%. Numerous augmentation agent have been tried which includes antipsychotics, anticonvulsants, antidepressants and NMDA antagonist. The NMDA antagonist such as Riluzole and Memantine have shown good efficacy in TRS. Therefore we are evaluating NMDA antagonist, dextromethorphan in TRS. The dextromethorphan or placebo will be administered along with clozapine in TRS patients. The study is randomized double blind placebo controlled group sequential trial.

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Key information

Conditions

Treatment Resistant Schizophrenia Mental Disorders Schizophrenia Schizophrenia Spectrum and Other Psychotic Disorders Schizophrenia, Treatment-Resistant

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

All India Institute of Medical Sciences (AIIMS)

Bhubaneswar, Odisha, 751019, India

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Schizophrenia patients who are diagnosed as treatment-resistant schizophrenia (TRS) defined as having been tried and not responded to any two antipsychotic medication for a duration of 6 weeks with dose equivalent of 600 mg of chlorpromazine and initiated on clozapine for the treatment of the same.
  • The patients who are on stable dose of clozapine.
  • Patients of either sex with age >18 years.
  • Patients for whom legally authorized representative (LAR) are willing to give informed consent.

Exclusion criteria

  • Patients with significant medical comorbidity.
  • Patients with significant psychiatric comorbidity.
  • Patients having active substance abuse history during the time of screening.
  • Female patients who are pregnant or in reproductive age not using contraception.
  • Female patients who are breast feeding

Treatment and study plan

dextromethorphan

Drug

Dextromethorphan 30mg will be administered along with Clozapine (standard of care) in treatment resistant schizophrenia.

Placebo

Drug

Matched placebo will be administered along with Clozapine (standard of care) in treatment resistant schizophrenia.

Primary outcomes

  1. Positive and negative symptom scale score

    Time frame: Baseline and 12 weeks

    The change in symptom scoring of schizophrenia at 12 weeks from baseline using Positive and negative symptom scale in the study groups. On this scale, total minimum score= 30, maximum score= 210. Higher score denotes a worse outcome.

Secondary outcomes

  1. Responder rate

    Time frame: 12 weeks

    To analyze and compare responder rate between study groups. The responder rate is defined as ≥ 20% reduction in PANSS score at 12 weeks from baseline.

  2. Incidence of clozapine resistance

    Time frame: 12 weeks

    To evaluate the proportion of patients developing clozapine resistance after 12 weeks of therapy.

  3. Requirement of clozapine dose modification

    Time frame: 12 weeks

    To evaluate the proportion of patients requiring clozapine dose increments or decrements over 12 weeks

  4. Clinical global impression scoring

    Time frame: 12 weeks

    To evaluate for clinical status according to the clinical global impression scale. Clinical global impression is presented in a scale of 1-7. High score denotes a worse outcome.

  5. Mini-mental state score

    Time frame: Baseline and 12 weeks

    The change in cognition as assessed by mini-mental state examination on a 30-point questionnaire at 12 weeks from baseline. Minimum and maximum score on this scale is 0 and 30. Lower score denotes worse outcome.

  6. Serum clozapine level

    Time frame: Baseline and 12 weeks

    To evaluate serum clozapine levels (trough level) at baseline and follow-up at 12 weeks.

  7. Incidence of treatment-emergent adverse events

    Time frame: 12 weeks

    To evaluate and compare the incidence of treatment-emergent adverse events in both groups.

Sponsors and collaborators

Lead sponsor

All India Institute of Medical Sciences, Bhubaneswar

Other

Registry information

Official study title

Dextromethorphan as an Augmentation Agent in Treatment-resistant Schizophrenia: A Randomized, Group Sequential Adaptive Design, Controlled Clinical Trial

Important dates

Study start
2023
Primary completion
2024
Study completion
2025
First posted
Jul 13, 2023
Registry last updated
May 9, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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