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Dextromethorphan as an Augmentation Agent in Treatment-resistant Schizophrenia

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

Status
Completed
Phases
Phase 4
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05944510
Enrollment
40
Registered
2023-07-13
Start date
2023-08-31
Completion date
2025-04-30
Last updated
2025-05-09

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Treatment Resistant Schizophrenia

Brief summary

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.

Interventions

DRUGDextromethorphan

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

DRUGPlacebo

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

Sponsors

All India Institute of Medical Sciences, Bhubaneswar
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

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

Design outcomes

Primary

MeasureTime frameDescription
Positive and negative symptom scale scoreBaseline and 12 weeksThe 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

MeasureTime frameDescription
Incidence of clozapine resistance12 weeksTo evaluate the proportion of patients developing clozapine resistance after 12 weeks of therapy.
Requirement of clozapine dose modification12 weeksTo evaluate the proportion of patients requiring clozapine dose increments or decrements over 12 weeks
Clinical global impression scoring12 weeksTo 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.
Responder rate12 weeksTo analyze and compare responder rate between study groups. The responder rate is defined as ≥ 20% reduction in PANSS score at 12 weeks from baseline.
Serum clozapine levelBaseline and 12 weeksTo evaluate serum clozapine levels (trough level) at baseline and follow-up at 12 weeks.
Incidence of treatment-emergent adverse events12 weeksTo evaluate and compare the incidence of treatment-emergent adverse events in both groups.
Mini-mental state scoreBaseline and 12 weeksThe 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.

Countries

India

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026