Background
Following earlier positive Selank trials in generalized anxiety disorder, this study examined Selank’s performance in a broader mixed anxiety-depressive disorder population — a more common clinical presentation in primary and psychiatric care settings. The comparator was medazepam, a milder daytime benzodiazepine used internationally.
The study also introduced a more rigorous cognitive assessment battery to quantify the cognitive tolerability advantage observed in prior work.
Methods
50 patients with ICD-10 mixed anxiety-depressive disorder randomized to:
- Selank 400 µg intranasal twice daily for 4 weeks
- Medazepam 10–20 mg/day orally for 4 weeks
Assessments at baseline, week 2, week 4:
- Hamilton Anxiety Scale (HAM-A) — primary
- Hamilton Depression Rating Scale (HAM-D) — secondary
- Hospital Anxiety and Depression Scale (HADS)
- Neuropsychological battery: attention, working memory, executive function
- Safety: CIWA (withdrawal), adverse event monitoring
Key Findings
Efficacy:
| Outcome | Selank | Medazepam | p (difference) |
|---|---|---|---|
| HAM-A reduction (wk 4) | −10.2 pts | −10.6 pts | ns (non-inferior) |
| HAM-D reduction (wk 4) | −6.1 pts | −5.8 pts | ns |
| HADS anxiety | Significant improvement | Significant improvement | ns |
| Response rate | 68% | 70% | ns |
Cognitive Outcomes:
- Selank: Stable or improved performance across all neuropsychological measures at week 4
- Medazepam: Significant impairments in attention (digit span), working memory, and processing speed
- The cognitive profile difference was statistically significant (p < 0.01) across measures
Tolerability:
- No withdrawal symptoms in Selank group at discontinuation
- 4 medazepam patients required dose reduction due to excessive sedation
- No serious adverse events in either group
Clinical Significance
This study strengthened the evidence base that Selank can match benzodiazepine anxiolytic efficacy while preserving — and possibly enhancing — cognitive function. This is clinically significant because:
- Working adults: Cognitive impairment from benzodiazepines significantly impacts occupational function; Selank allows treatment without work interference
- Elderly patients: Benzodiazepines are high-risk in elderly (falls, delirium); Selank’s cognitive safety makes it a candidate for this vulnerable group
- Mixed anxiety-depression: The modest antidepressant signal (HAM-D improvement) suggests broader utility than pure anxiolytics
Limitations
- Russian single-center study; external validity to international populations is uncertain
- No placebo arm — cannot determine absolute efficacy
- 4-week endpoint; longer-term efficacy data are absent
- Intranasal dose standardization and bioavailability consistency are not confirmed across patients
- Study not yet replicated in a Western regulatory context (FDA/EMA)