⚠ Educational reference only — not medical advice.** This article is for research and educational reference. Always consult your own physician before considering any peptide protocol. See the full Disclaimer at the end of this article.

Introduction
P-21 is an IGF-1-derived peptide investigated in preclinical neuroscience, developed in the laboratory of Pedersen and colleagues. Structurally inspired by a portion of IGF-1 with modifications intended to retain neurogenic and cognitive-supportive activity while reducing the systemic anabolic and proliferative effects of full IGF-1. Strictly investigational; no approved clinical indication.

Mechanism of Action
Reported to enhance hippocampal neurogenesis, reduce neuroinflammatory markers, and improve performance on memory-dependent behavioral tasks in rodent models. Designed to lack the canonical IGF-1-receptor binding profile that drives the hypoglycemic and mitogenic effects of full IGF-1, though human receptor-level characterization is incomplete.

Research Indications
Preclinical: cognitive aging, Alzheimer’s-disease models, traumatic brain injury recovery. No human efficacy data of clinical-grade rigor.

Reconstitution
Typical 5 mg lyophilized vial: add **2.5 mL of bacteriostatic water**, swirl gently. Final concentration **2000 mcg/mL (2 mg/mL)** — each 0.05 mL (5 units on a U-100 insulin syringe) delivers 100 mcg.

Dosing Protocol (research literature)
Human dosing is not well characterized. Research protocols extrapolated from preclinical work typically use **100–250 mcg subcutaneously once daily** for **8–16 weeks** before reassessment. Some protocols cycle 5 days on / 2 days off.

Administration
Subcutaneous into abdominal fat, rotating sites. AM dosing aligns with cognitive-endpoint study designs.

Storage & Handling
Lyophilized: refrigerate (2–8°C). Reconstituted: refrigerate; stable approximately **14–21 days**. Protect from light.

Side Effects
Human safety data are limited. Theoretical concerns include any unintended IGF-1-receptor-mediated effects (hypoglycemia, mitogenic stimulation) and CNS effects not systematically characterized.

Contraindications
Pregnancy, lactation, active malignancy, poorly controlled diabetes.

Monitoring
Baseline cognitive instruments (MoCA or domain-specific tasks appropriate to the protocol), fasting glucose, HbA1c. Re-measure at 8 and 16 weeks.

Disclaimer
**This article is for informational and research-reference purposes only.** Nothing in this document constitutes medical advice, a prescription, or a recommendation from a physician. The reconstitution, dosing, and protocol information above reflects ranges commonly cited in published research and clinician-directed protocols — it is provided as reference material only, not as instructions, an endorsement of off-label use, or a substitute for individualized medical evaluation.

**Customers should do their own research and consult their own physician** before considering any peptide protocol. Whether a given compound is appropriate for an individual — and at what dose, for what duration, and alongside what monitoring — is a decision that only a licensed clinician with knowledge of that individual’s medical history, current medications, and conditions can make.