Selank: Dosing Protocols

Research Dosing Disclaimer#

The dosing information below is derived from research studies and is provided for educational purposes only. Selank is not approved for human use, and no official dosing guidelines exist.

Dose-Response Data#

We synthesized animal dose–response data for Selank (Thr–Lys–Pro–Arg–Pro–Gly–Pro), focusing on body‑weight–normalized doses, routes, schedules, and observed outcomes across species.

• Rats, intranasal, single dose: 250 and 500 μg/kg increased hippocampal Bdnf mRNA at 3 h and BDNF protein at 24 h versus vehicle, indicating molecular efficacy in the low hundreds of μg/kg range after one administration.

• Rats, intranasal, 200 μg/kg: a single 200 μg/kg dose altered mRNA levels of 36 hippocampal genes; a “curative” course of 200 μg/kg once daily for 5 days altered 20 genes, with overlapping but also divergent responders (e.g., Cx3cr1 decreased after a single dose but increased nearly threefold after the 5‑day course; Slc8a3 increased ~4.2× after the 5‑day course), demonstrating schedule‑dependent transcriptional responses at a fixed body‑weight–normalized dose.

• Rats, intraperitoneal (IP), single dose 300 μg/kg, antenatal hypoxia model: Selank improved learning performance (about 1.5× faster acquisition) and normalized indices of exploratory behavior; neurochemically, it increased noradrenaline and dopamine across neocortex, hypothalamus, and brainstem, while altering serotonin (e.g., neocortex decrease), supporting functional effects at 300 μg/kg IP.

• Mice, strain dependence and dose range: In BALB/c mice, Selank showed anxiolytic/activating effects in open‑field testing after 300 μg/kg IP (significant increases in peripheral and central movement vs controls), whereas C57BL/6 mice did not respond under comparable conditions. Broader reports indicate anxiolytic efficacy in BALB/c across ~200–3000 μg/kg, highlighting a strain‑specific dose–response window.

• Mice, dopaminergic hyperactivity model: IP Selank over a wide range (10–10,000 μg/kg) reduced apomorphine‑induced hyperactivity and interacted with naloxone, indicating activity across several orders of magnitude in dose for this endpoint.

• Rats, antidepressant‑like effects at higher repeated doses: Repeated IP administration at 1000–2000 μg/kg reduced or eliminated depressive‑like behaviors without affecting general locomotion, suggesting that higher daily doses are required for antidepressant‑like outcomes relative to anxiolysis/learning effects.

• Primates, systemic dosing: Reports in primates describe dose‑dependent recovery dynamics, where a higher dose (300 μg/kg) produced a longer duration of recovery than lower doses (30–50 μg/kg), suggesting a positive dose–duration relationship within this range.

• Rats, chronic social stress model, IP 100 μg/kg/day ×20: Chronic administration normalized anxiety/depression‑like behaviors in open field and restored immune parameters (e.g., DTH reaction, phagocytic activity, leukocyte formula), indicating efficacy at 100 μg/kg/day over weeks in a stress‑induced model.

Key patterns and practical notes

• Effective CNS‑relevant doses in rodents commonly cluster at 200–500 μg/kg for intranasal single administrations (molecular readouts such as BDNF) and around 300 μg/kg for single IP behavioral/monoamine effects; chronic stress/immunomodulation studies used 100 μg/kg/day IP for 2–3 weeks.
• Behavioral anxiolysis shows marked strain dependence in mice, with BALB/c responsive across 200–3000 μg/kg IP, while C57BL/6 are comparatively insensitive under similar testing, emphasizing that apparent dose–response can be genotype‑contingent.
• Antidepressant‑like effects in rats appear to require higher repeated dosing (≥1000 μg/kg/day IP), distinct from the lower doses effective for anxiolysis or learning enhancement.
• Very broad IP ranges (10–10,000 μg/kg) can modulate specific pharmacological challenges (apomorphine hyperactivity), but such breadth likely reflects model sensitivity and does not imply equipotency across endpoints.

Summary table of doses, routes, and outcomes

Limitations

• Some reports are summarized from a comprehensive review, and for several entries routes/schedules are implied rather than explicitly repeated in each experiment; nevertheless, the body‑weight–normalized doses and outcomes are consistently reported in the cited texts.

Administration Routes#

Objective. To compare pharmacokinetics and bioavailability of Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) by administration route—subcutaneous (SC), oral, intramuscular (IM), and topical/transdermal—using available primary evidence; to identify gaps and constraints.

Summary of available evidence. Direct route-resolved pharmacokinetic data for Selank are sparse outside intranasal studies. Radiolabeled and mechanistic work characterize rapid proteolytic degradation in plasma and early tissue distribution after intranasal (i.n.) and intraperitoneal (i.p.) dosing; comparative radiolabel experiments also included intragastric (i.g.) and intravenous (i.v.) administration, but did not report absolute bioavailability, Tmax, Cmax, or half-life for SC/IM/topical routes. In vitro assays show rapid plasma degradation dominated by dipeptidyl carboxypeptidases generating shorter fragments (e.g., TKPRP, TKP, RP, GP), which are detected in blood and brain following administration (various routes). A secondary source summarizing intranasal PK reports rapid appearance in plasma (~30 s) and brain (~2 min) and high apparent intranasal bioavailability, in contrast to i.p. where early brain uptake is lower; however, formal systemic PK parameters are not provided.

Route-by-route comparison. A structured synthesis of what is and is not known for each requested route is presented below.

Interpretation by route (narrative).

• Subcutaneous (SC): No direct Selank SC pharmacokinetic studies were identified. Given documented rapid plasma proteolysis of Selank and fragments observed after other parenteral routes, systemic persistence after SC injection is unknown and cannot be inferred from the available data. No SC bioavailability, Tmax, Cmax, or tissue-distribution datasets were found.

• Intramuscular (IM): No direct Selank IM pharmacokinetic studies were identified. As with SC, the only firm conclusion from the current evidence base is rapid enzymatic susceptibility once Selank reaches plasma; IM-specific absorption rate, bioavailability, and exposure metrics have not been reported.

• Oral (per os; intragastric in animals): Comparative radiolabel distribution work including intragastric administration demonstrates prominent gastric tissue radioactivity and does not provide intact-peptide systemic PK (no oral bioavailability, Tmax, or Cmax). Coupled with the demonstrated rapid proteolysis in plasma and the general susceptibility of Selank to peptidases, the available data are consistent with poor systemic availability of intact Selank after oral dosing unless protective formulations are used, but quantitative oral bioavailability has not been established.

• Topical/transdermal: No Selank-specific dermal or transdermal pharmacokinetic studies were retrieved. The extant Selank evidence documents rapid proteolysis in biological fluids but does not address skin permeation, enhancers, or systemic exposure from the skin; therefore, bioavailability and route-specific PK remain uncharacterized for topical/transdermal administration.

Context from intranasal and intraperitoneal data. Intranasal administration shows the most robust evidence for rapid CNS access and suggests higher apparent efficiency for brain delivery relative to i.p. at early time points (e.g., olfactory-bulb enrichment several-fold above blood at ~3 min in radiolabeled rats). A secondary report cites high intranasal bioavailability (~92.8%) and very rapid detection in plasma and brain, though formal intact-peptide AUC/Cmax and absolute bioavailability calculations are not presented. After i.p. administration, early brain radioactivity is lower than with i.n., and rapid distribution to abdominal organs is observed, consistent with first-pass tissue uptake and concurrent proteolysis of the peptide.

Mechanistic stability insights relevant across routes. In vitro and in vivo analyses consistently show that Selank is rapidly cleaved predominantly by dipeptidyl carboxypeptidases, yielding shorter fragments (e.g., TKPRP, TKP, RP, GP) detectable in blood and brain; aminopeptidases make a smaller contribution. The in vitro plasma half-life is on the order of minutes, underscoring that any systemic bioavailability estimates should distinguish intact peptide from metabolites and that route-specific absorption must be evaluated in studies capable of resolving intact Selank from its fragments.

Conclusions and evidence gaps. For the specific routes requested—SC, IM, oral, and topical—no direct Selank pharmacokinetic datasets quantifying bioavailability, Tmax, Cmax, or systemic half-life were located. Available primary evidence supports rapid proteolysis after entry into circulation and route-dependent early distribution for i.n. versus i.p.; it also highlights prominent gastric tissue radioactivity in comparative studies that included intragastric dosing. Definitive comparisons of bioavailability across SC/IM/oral/topical routes will require new, route-specific studies using intact-peptide–selective analytical methods and time-course sampling.

Human-Equivalent Dosing#

Objective. We examined how animal study doses of Selank have been scaled to human-equivalent doses (HED) and which allometric methods are used in the literature.

Findings about Selank studies. In accessible primary reports, Selank animal studies typically report doses without performing HED conversion. For example, intranasal Selank was administered to rats at 250–500 µg/kg as a single dose, with hippocampal BDNF endpoints; no interspecies scaling or HED calculation was provided. In mice, intraperitoneal Selank was tested at 0.01–10 mg/kg in behavioral assays, and other rodent regimens used 100–200 µg/kg; again, no HED or explicit allometric method was reported.

Allometric scaling methods used in the broader literature. When animal doses are translated to humans, biomedical studies commonly employ body-surface-area (BSA)–based allometry using Km factors. A methodological source explicitly states: HED (mg/kg) = Animal dose (mg/kg) × (Km_animal / Km_human), where Km reflects the body‑weight to surface‑area relationship; this approach is described as the recommended method over direct mg/kg extrapolation, and is attributed to FDA-style guidance. Translational papers frequently cite practical guides such as Nair & Jacob (2016) for applying these Km tables, even for peptide drugs; for example, GLP‑1/semaglutide translational work cites this guide for dose conversion principles. Some studies further refine HED by combining BSA normalization with adjustments for differences in oral bioavailability or exposure (AUC) between species; as an example, sorafenib dosing was converted by BSA and then adjusted for oral bioavailability, yielding concrete human‑equivalent regimens from mouse/monkey data. Reviews and translational reports also restate a heuristic derived from BSA scaling that human mg/kg doses are roughly an order of magnitude lower than mouse mg/kg doses (often approximated as ~12‑fold), though the exact factor depends on Km values.

Conclusion. In the Selank animal literature we located, authors reported species, routes, and dose levels but did not present HED calculations or specify allometric methods. In the broader translational literature, BSA/Km‑based allometric scaling is the predominant method, often guided by FDA‑style recommendations and practical tables; some studies incorporate bioavailability or PK adjustments when routes or absorption differ. Therefore, to scale Selank animal doses to HED in the absence of Selank‑specific guidance, the standard approach would be to apply BSA/Km‑based conversion and consider route‑ and bioavailability‑related adjustments if needed.

Evidence Gaps#

• No human dose-finding studies have been completed
• Allometric scaling from animal models has inherent limitations
• Route-specific bioavailability data in humans is absent
• Optimal treatment duration has not been established

Related Reading#

• Selank overview and research guide
• Selank side effects profile
• Selank research evidence