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Substance P11 residuesRPKPQQFFGLMEach bubble = one amino acid. Size = residue mass. Color = chemical class.Also known as: SP, Tachykinin Precursor 1 fragment, Neurokinin 1 ligand
Over 20,000 PubMed citations since 1931, yet zero human clinical trials for wound healing. Substance P is an endogenous 11-amino-acid neuropeptide (Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2) of the tachykinin family that signals through the neurokinin-1 receptor (NK1R). Its tissue half-life sits around 1 to 2 minutes. Neutral endopeptidase (NEP) chews through it almost immediately after release. Preclinical models show Substance P mobilizes bone marrow stem cells, accelerates wound closure, and drives angiogenesis. But the pharmacokinetics make subcutaneous self-administration largely impractical for systemic benefit. This is a laboratory research molecule, not a consumer peptide.
Eleven amino acids. One of the oldest known neuropeptides in biomedical science. Substance P (SP, also tachykinin precursor 1 fragment; CAS 33507-63-0) was first isolated from horse brain and intestine by Ulf von Euler and John Gaddum in 1931, making it one of the first neuropeptides ever described. SP binds the neurokinin-1 receptor (NK1R) on neurons, immune cells, keratinocytes, and endothelial cells. That single receptor mediates a paradox: the same signaling that amplifies pain also kicks off wound repair. Kim and colleagues confirmed this in a 2009 Nature Medicine study [1], showing that IV Substance P mobilized CD29+/CD45-/CD11b- stromal-like cells from bone marrow in mice, rats, and rabbits. Khalifa's group extended the picture in 2024 [2], demonstrating that SP restores asymmetric stem cell divisions in denervated skin wounds. The clinical reality is more complicated. NEP (neutral endopeptidase, also called CD10) degrades SP in tissue within 1 to 2 minutes. Subcutaneous bioavailability registers as "very low" because local enzymatic destruction outpaces systemic distribution. No self-administration community exists. No consumer peptide vendors stock it. Research-grade SP runs $50 to $150 per milligram from institutional suppliers like Sigma-Aldrich (catalog S6883). The most pharmacologically rational application, topical SP-fragment eye drops for corneal healing, has the closest thing to human evidence, but even that sits at case-series level.
Substance P binds with high affinity to the neurokinin-1 receptor (NK1R), a Gq/11-coupled GPCR expressed across neurons, immune cells, keratinocytes, and vascular endothelium. Receptor activation triggers phospholipase C, releasing inositol trisphosphate (IP3) and diacylglycerol (DAG). Intracellular calcium spikes. Protein kinase C (PKC) activates. In nociceptive C-fibers, that cascade amplifies pain signals transmitted from peripheral nerve terminals to the spinal dorsal horn. SP co-localizes with CGRP in sensory neurons; the two peptides are often released together during neurogenic inflammation. The immune arm of NK1R signaling is equally aggressive. Mast cells degranulate, dumping histamine and proteases. Macrophages and neutrophils get recruited via chemotaxis. T-cells proliferate. Cytokine output increases across IL-1, IL-6, and TNF-alpha. That inflammatory burst, while uncomfortable in the short term, is the opening phase of wound healing. The repair arm follows. SP stimulates fibroblast proliferation and collagen synthesis at the wound site. It upregulates vascular endothelial growth factor (VEGF), driving angiogenesis. The bone marrow mobilization pathway (Kim 2009)[1] recruits CD29+ stromal-like cells from marrow to peripheral injury sites. Khalifa's 2024 data [2] added that SP specifically restores asymmetric stem cell division in denervated tissue, a mechanism lost when sensory innervation is damaged.
Preclinical data (animal models, in vitro) consistently supports NK1R-mediated wound healing, bone marrow stem cell mobilization, and corneal epithelial repair. Zero human clinical trials exist for systemic wound healing use. SC route likely pharmacologically ineffective for systemic benefit due to ~1-2 min tissue half-life and very low SC bioavailability.
Kim et al. 2009, Nature Medicine (PMID 19270709): IV SP mobilizes CD29+/CD45−/CD11b− stromal-like cells from bone marrow in mice, rats, and rabbits; Khalifa et al. 2024, Stem Cells (PMID 38301639): SP restores asymmetric stem cell divisions in denervated skin wounds (2024)
All wound healing data is preclinical. No human RCTs for systemic SP wound healing. SC bioavailability is very low: rapid NEP-mediated extracellular degradation. Simultaneous pro-nociceptive and pro-inflammatory effects complicate therapeutic use. Plasma half-life (hours, ACE-mediated) differs from tissue half-life (~1-2 min, NEP-mediated).
No self-administration community exists. Substance P is not discussed or used in biohacker, peptide, or sports medicine communities. It is a laboratory research reagent with no consumer peptide market presence.
Substance P has no self-administration community. All available data is from preclinical research (animal models, in vitro studies). There is no community experience to align or diverge from the scientific literature. This is a laboratory research molecule only.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 50mcg | Single dose (local injection near wound site) |
| Moderate | 100mcg | Single dose (local injection near wound site) |
| Aggressive | 200mcg | Single dose (local injection near wound site) |
Start with two practical realities. First: Substance P is not sold by consumer peptide vendors. You need a research-grade source (Sigma-Aldrich S6883 or Tocris #1156), and most require institutional purchasing credentials. Second: the 1 to 2 minute tissue half-life means distant subcutaneous injection (abdomen for a knee wound, for example) is pharmacologically pointless. Inject directly at or immediately adjacent to the target tissue. Reconstitution math for a 2 mg vial: add 2 mL bacteriostatic water. Concentration equals 1 mg/mL, or 1 mcg per uL. A 50 mcg dose equals 50 uL, which is 5 units on a U-100 insulin syringe. A 100 mcg dose equals 10 units. A 200 mcg dose equals 20 units. For a 5 mg vial with 2 mL BAC water: concentration is 2.5 mg/mL, or 2.5 mcg per uL. A 50 mcg dose equals 20 uL (2 units). A 100 mcg dose equals 40 uL (4 units). Aliquot into single-use volumes immediately after reconstitution. SP is sensitive to oxidation and protease contamination. Do not store reconstituted solution beyond 7 days at 2 to 8 degrees Celsius. Avoid freeze-thaw cycles entirely.
Due to its pro-inflammatory nature, extended continuous use is not recommended. Short research cycles with equal off-periods are standard practice. Monitor inflammatory markers.
Substance P is inherently pro-inflammatory via NK1R activation. Extended continuous use risks chronic neurogenic inflammation, mast cell hyperactivation, progressive pain sensitization, and potentially exacerbation of pre-existing inflammatory conditions. Standard research practice uses short cycles (4 weeks max) with equal off-periods. No receptor desensitization data exists to inform a specific cycle length: the 4-on/4-off recommendation is precautionary based on pro-inflammatory pharmacology.
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Expected: Preclinical: accelerated wound closure, increased fibroblast/keratinocyte proliferation, angiogenesis markers at wound site. No human evidence. Systemic effects from SC are unlikely given rapid NEP-mediated local degradation.
Monitor: Monitor for neurogenic inflammation (erythema, edema, pain amplification) at injection site. Check CRP/ESR at week 2 if continuing. Contraindicated in asthma: monitor spirometry if respiratory history.
Verify the certificate of analysis shows at least 95% HPLC purity and correct molecular weight (1,347.63 Da). Research-grade only.
Add 2 mL bacteriostatic water to a 2 mg vial. Swirl gently. Do not shake or vortex. Final concentration: 1 mcg per uL.
For a 50 mcg beginner dose, draw to the 5-unit mark on a U-100 insulin syringe. For 100 mcg (moderate), draw to 10 units. For 200 mcg (aggressive), draw to 20 units.
Inject subcutaneously at or immediately adjacent to the target wound or tissue site. Use a 29 to 31 gauge, 1/2 inch insulin needle. Clean the site with alcohol first.
Erythema, warmth, and pain amplification at the injection site are normal NK1R pharmacology. These should resolve within hours.
Store the remaining reconstituted vial at 2 to 8 degrees Celsius. Use within 7 days. Aliquoting into single-use volumes at reconstitution time is strongly recommended.
Track wound site with dated photographs. Check CRP/ESR at week 2 if continuing past the first week. Stop if erythema persists beyond 24 hours, pain becomes disproportionate, or any respiratory symptoms develop.
5–250 nmol/kg continuous infusion (animal studies); 10 nM/kg single IV dose for stem cell mobilization (Kim 2009). Continuous infusion required due to 1-2 min tissue half-life.
IV is the only route achieving meaningful systemic exposure in published research. Used in the landmark Kim 2009 Nature Medicine CD29+ stem cell mobilization study. Requires clinical research setting with hemodynamic monitoring. Not a self-administration option. Potent vasodilation at higher doses: hypotension risk.
1 mM solution, 5 µL per drop, 4–6x daily; bypasses systemic enzymatic degradation by acting locally at corneal surface
SP-fragment (FGLM-amide) + IGF-1 combination drops used in Japanese ophthalmology case series for persistent corneal epithelial defects. 2024 AJP Cell Physiology study (Sugioka) confirms SP potentiates TGF-β-driven corneal collagen synthesis via NK1R/p38 MAPK. Biomolecules 2025 review (PMC12109903) covers dual pro-repair/pro-inflammatory SP role in cornea. Most pharmacologically rational SP application given the half-life constraints.
50–200 mcg near wound site (speculative; no validated human dose: see FLAG P0)
SC bioavailability is "very low" per site pkData. Injection directly at wound site maximizes local exposure before enzymatic degradation. Systemic benefit from distant SC injection is pharmacologically unsupported. All community dosing values (50/100/200 mcg) are unsourced extrapolations.
Directly block NK1R: will completely negate all SP effects. Pharmacological opposites. Note: tradipitant was FDA-approved December 2025 for motion sickness.
Do not combineACE is a primary SP degradation enzyme. ACE inhibition prolongs and potentiates SP activity unpredictably, intensifying both pro-inflammatory and pro-nociceptive effects. Also contributes to ACEi-associated dry cough mechanism (alongside bradykinin).
Neutral endopeptidase (NEP/neprilysin) is the primary tissue-degradation enzyme for SP. NEP inhibition (as in sacubitril, part of sacubitril/valsartan) could markedly prolong SP tissue exposure and amplify neurogenic inflammation.
NK1R activation is inherently pro-inflammatory and pro-nociceptive. Pain amplification at the injection site is expected pharmacology, not a side effect to push past. SP stimulates C-fiber nociceptors and sensitizes dorsal horn neurons. If you inject near a wound, local pain will increase before any healing benefit appears. Mast cell degranulation occurs within minutes. Histamine release causes vasodilation, edema, and erythema at the injection site. In most subjects this resolves within hours as NEP degrades the peptide. Persistent erythema or edema beyond 24 hours signals that tissue inflammatory load has exceeded the acute phase, and dosing should stop. Bronchoconstriction in susceptible individuals is the most dangerous acute risk. NK1R sits on airway smooth muscle. SP-mediated bronchoconstriction in anyone with asthma, COPD, or reactive airway disease could trigger a medical emergency. Spirometry screening before any use is mandatory. Any wheezing, chest tightness, or respiratory discomfort after injection means immediate discontinuation with no rechallenge. Nausea and flushing have been reported across SP infusion studies. These reflect systemic vasodilatory and emetic pathway activation through NK1R in the brainstem area postrema, the same receptor targeted by aprepitant (Emend) for chemotherapy-induced nausea. Neuropsychiatric exacerbation is a real concern. Substance P levels are raised in major depression, anxiety disorders, and PTSD (O'Connor et al., J Cell Physiol 2004)[4]. Exogenous administration could worsen these conditions. Screen for active psychiatric symptoms before any research use. Published human data on exogenous SP administration is extremely thin. Corneal SP-fragment eye drops represent the most tested human route, and even those are case-series level. Systemic IV infusion studies have included fewer than 50 total subjects across all publications. There is no long-term safety data for any route. Pregnancy and breastfeeding: no safety data exists. Absolute contraindication. Active malignancy: SP and NK1R signaling have been implicated in tumor growth and angiogenesis in preclinical models. Do not use with any active cancer diagnosis.
Verify Substance P dosing and safety with a second opinion
Substance P is a laboratory research reagent, not a consumer peptide vendor product. It is rarely if ever stocked by consumer peptide suppliers. Research-grade sources require institutional accounts (Sigma-Aldrich, Tocris). Fisher Scientific/Cayman Chemical distribution channel was reported discontinued as of early 2026 check. No compounding pharmacy access: SP is not on FDA 503A/503B bulk substance nominated lists. Any consumer source would require extraordinary purity verification.
| Test | When | Target |
|---|---|---|
| C-reactive protein (CRP) and/or erythrocyte sedimentation rate (ESR) | Baseline before starting; repeat at week 2 if continuing | CRP <10 mg/L; ESR within age/sex normal limits |
| Spirometry / Peak expiratory flow | Before starting: contraindicated if obstructive pattern (FEV1/FVC <0.7) or any reactive airway history | — |
| Local wound site assessment (photography + measurement) | At each injection session and weekly | — |
SP is pro-inflammatory via NK1R. Systemic inflammatory markers elevation signals excessive or unintended systemic inflammatory response.
SP induces bronchoconstriction via NK1R on airway smooth muscle. This is a hard contraindication in asthma/COPD.
Primary endpoint for any wound healing application. Distinguishes therapeutic wound healing response from pathological neurogenic inflammation. Documented photo record allows objective assessment of wound closure rate.
Rapid NK1 receptor activation. Immediate vasodilation and plasma extravasation at injection site. Mast cell degranulation and histamine release may occur. Effects are transient due to ~1-2 minute half-life.
Neurogenic inflammatory response peaks. Localized edema, erythema, and immune cell recruitment observed. Fibroblast and keratinocyte stimulation begins at the tissue level.
With repeated dosing, measurable increases in local immune cell infiltration and early wound healing markers. Bone marrow stem cell mobilization begins in animal models.
Accelerated wound closure and re-epithelialization observed in corneal and dermal wound models. Angiogenesis markers (VEGF) elevated. Collagen deposition increased at wound sites.
Maximal tissue repair effects in research models. Continued immune modulation. Evaluate inflammatory markers to ensure no chronic inflammation. Consider cycling off.
Minutes 0 to 30 post-injection: NK1R activates within seconds at the injection site. Mast cells degranulate, releasing histamine. Local vasodilation and plasma extravasation begin immediately. Pain amplification at the site is expected. These effects are transient because NEP degrades SP in tissue within 1 to 2 minutes. Systemic exposure from subcutaneous injection is minimal. Hours 1 to 6: Neurogenic inflammation peaks at the injection site. Neutrophils and macrophages begin arriving. Fibroblast and keratinocyte stimulation starts through downstream NK1R signaling. Local edema and erythema continue. Pain at the injection site persists. Days 1 to 3: With repeated daily dosing, local immune cell infiltration becomes measurable. Early wound healing markers begin to rise in animal models. Kim's 2009 data [1] showed bone marrow stem cell mobilization starting within this window in mice and rabbits. No human data confirms this timeline. Weeks 1 to 2: Preclinical wound models show accelerated wound closure and re-epithelialization. VEGF levels climb at wound sites. Collagen deposition increases. Khalifa's 2024 work [2] confirmed SP restores asymmetric stem cell divisions in denervated skin during this window. All of this is animal model data. Weeks 3 to 4: Maximum tissue repair effects observed in research models. Inflammatory marker monitoring becomes critical. CRP and ESR should be checked. Chronic neurogenic inflammation risk increases with continued use. Standard research practice calls for cycling off at week 4 with an equal 4-week off period before any rechallenge.
Rapid NK1R binding within seconds. Mast cell degranulation, histamine release, vasodilation, plasma extravasation at injection site. Effects are transient: tissue half-life is ~1-2 min (extracellular NEP-mediated). Plasma half-life is hours but systemic exposure from SC is minimal.
No community data: no self-administration reports exist.
Peak neurogenic inflammatory response at injection site. Neutrophil and macrophage recruitment begins. Fibroblast and keratinocyte stimulation initiates via NK1R and downstream signaling.
No community data.
With repeated dosing: measurable increases in local immune cell infiltration, early wound healing marker elevation. Bone marrow stem cell mobilization begins in animal models (Kim 2009 PMID 19270709).
No community data.
Accelerated wound closure and re-epithelialization in corneal and dermal animal wound models. Elevated VEGF, increased angiogenesis. Collagen deposition increased at wound sites. Khalifa 2024 (PMID 38301639): SP restores asymmetric stem cell divisions in denervated skin.
No community data.
Maximal tissue repair effects observed in animal models. Extended use risks chronic neurogenic inflammation. Inflammatory marker monitoring recommended. Cycling off standard practice in research protocols.
No community data.
Source: Substance P is rapidly degraded by neutral endopeptidase (NEP/CD10) and angiotensin-converting enzyme (ACE) with a plasma half-life of approximately 1-2 minutes (PMID 24286369)
Loading the interactive decay curve.
Substance P holds research-only regulatory status. It has no FDA approval for any therapeutic indication. No NDA or IND for systemic wound healing has been filed as of April 2026. SP is not listed on the FDA 503A or 503B bulk substance nominated lists, so compounding pharmacies cannot legally prepare it for patient use. It is not scheduled under the Controlled Substances Act. WADA does not currently list Substance P as a prohibited substance, though peptide hormones and growth factors as a class carry restrictions under section S2. Sourcing is limited to research chemical suppliers. Sigma-Aldrich (catalog S6883, acetate salt hydrate) and Tocris (catalog #1156) are the two most cited sources in published literature. Both typically require institutional purchasing accounts. Any consumer vendor claiming to stock Substance P warrants extreme skepticism regarding purity and identity. All content on this page is for educational and informational purposes only. Nothing here constitutes medical advice, diagnosis, or treatment recommendations. Consult a qualified healthcare provider before making any decisions about peptide use.
Peptide Schedule Research TeamReviewed Apr 20269 Citations
