If you've been researching natural or novel approaches to anxiety treatment, you've probably come across Selank. Unlike traditional anti-anxiety medications, Selank is a synthetic peptide that has attracted interest because it may reduce anxiety without many of the sedating side effects associated with benzodiazepines.

One of the most frequently cited clinical studies examining Selank was published in 2008 in the S.S. Korsakov Journal of Neurology and Psychiatry. The researchers investigated whether Selank could effectively treat generalized anxiety disorder (GAD) and neurasthenia, while also exploring how it might work biologically.

What is Selank?

Selank is a synthetic peptide developed as an analog of tuftsin, a naturally occurring immune-regulating peptide. Previous laboratory research had suggested that Selank may reduce anxiety by inhibiting enzymes that break down enkephalins—naturally occurring opioid peptides involved in regulating stress, mood, and emotional responses.

The 2008 study aimed to determine whether these biological effects translated into meaningful improvements in people experiencing anxiety disorders.

The Clinical Trial

The study included 62 adults between the ages of 18 and 55.

Participants were diagnosed with either:

• Generalized Anxiety Disorder (GAD)
• Neurasthenia (a condition characterized by persistent fatigue, weakness, irritability, and anxiety-related symptoms)

Researchers compared Selank with medazepam, a benzodiazepine anxiolytic commonly used at the time.

• 42 participants received Selank
• 20 participants received medazepam

Throughout treatment, anxiety symptoms were measured using several well-established clinical rating scales, including:

• Hamilton Anxiety Rating Scale (HAM-A)
• Zung Self-Rating Anxiety Scale
• Clinical Global Impression (CGI)

In addition to clinical outcomes, researchers measured serum enkephalinase activity, which reflects how quickly the body breaks down Leu-enkephalin, one of the body's naturally occurring opioid peptides.

• Drug: Selank (0.15% nasal drops)
• Route: intranasal
• Daily dose: 2700 µg (2.7 mg) per day, split into 3 doses
• Drop math used in those materials: 1 drop ≈ 75 µg, so 2700 µg/day ≈ 36 drops/day
• Course: 14 days
• Comparator: medazepam 30 mg/day
• Sample: 62 patients (30 Selank, 32 medazepam) with GAD or neurasthenia

What Did the Study Find?

Anxiety improved similarly to a benzodiazepine

The researchers found that Selank reduced anxiety to a similar degree as medazepam. Across multiple clinical rating scales, there were no significant differences in overall anxiolytic effectiveness between the two treatments.

Two Patterns of Responses

The investigators described two patterns of response:

• Approximately 40% of patients experienced very rapid improvement, sometimes within the first one to two days.
• The remaining 60% improved more gradually, with symptoms beginning to decrease around the third day of treatment.

Among those who improved, reductions were seen in:

• Excessive worrying
• Internal tension
• Sleep disturbances
• Headaches related to anxiety
• Emotional distress

Selank appeared to improve fatigue and energy

One finding that distinguished Selank from medazepam was its apparent effect on asthenia, or fatigue.

Participants taking Selank experienced improvements in:

• Fatigue
• Daytime sleepiness
• Energy
• Physical endurance
• Mental work capacity

The authors described these as anti-asthenic and psychostimulant effects, which are quite different from the sedating effects often associated with benzodiazepines.

Fewer side effects were reported with Selank 

The tolerability findings were also notable.

Only three patients experienced side effects that investigators believed were likely related to Selank, and these were described as mild and short-lived.

The researchers also reported:

• no evidence of withdrawal symptoms
• no signs of drug dependence after treatment

By comparison, approximately 65% of participants taking medazepam experienced side effects, including:

• Drowsiness
• Dizziness
• Nausea
• Muscle weakness
• Dry mouth

Many of these side effects became more noticeable over the course of treatment.

The Bottom Line

Based on this 2008 clinical study, Selank may be an extremely promising therapy for anxiety, with less side effects than benzodiazepines.

The trial found that Selank:

• Reduced anxiety to a degree comparable with the benzodiazepine medazepam.
• Produced fewer sedating side effects.
• Appeared to improve fatigue and daytime functioning.
• May work by slowing the breakdown of naturally occurring opioid peptides known as enkephalins.

References

[Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia] [Article in Russian]Zozulia, A. A., Neznamov, G. G., Siuniakov, T. S., Kost, N. V., Gabaeva, M. V., Sokolov, O. I.u, Serebriakova, E. V., Siranchieva, O. A., Andriushenko, A. V., Telesheva, E. S., Siuniakov, S. A., Smulevich, A. B., Miasoedov, N. F., & Seredenin, S. B. (2008). Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova, 108(4), 38–48.