What Is Diaminopyrimidine Oxide?
Diaminopyrimidine Oxide, commonly known in the hair care industry as Kopexil (CAS 74638-76-9), is a synthetic compound from the pyrimidine family. It is widely used in hair care products as a conditioning and anti-hair loss active ingredient.
Structurally, it shares similarities with minoxidil - the well-known hair growth treatment agent - while being classified strictly as a cosmetic raw material rather than a pharmaceutical ingredient. This allows cosmetic formulators to develop effective anti-hair loss formulations following cosmetic regulatory standards, without the strict approval requirements for pharmaceutical drugs.
This ingredient is commonly incorporated into a wide range of hair products, including shampoos, conditioners, serums, tonics, and scalp lotions. It acts as both a hair conditioning and scalp care agent, maintaining scalp health while improving the internal causes of premature hair loss.
Mechanism of Action
Diaminopyrimidine Oxide supports hair growth and reduces hair loss through multiple biological pathways:
- 5α-Reductase Inhibition
It inhibits 5α-reductase, the enzyme that converts testosterone into dihydrotestosterone (DHT). Excess DHT is a main cause of hair follicle miniaturization in androgenetic alopecia. Regulating local DHT levels around follicles, it helps sustain normal hair growth.
- Potassium Channel Activation
Similar to minoxidil, this ingredient can activate potassium channels in hair follicle cells, promoting vasodilation and improving scalp microcirculation. Better blood flow delivers more oxygen and nutrients directly to hair roots.
- Anagen Phase Prolongation
It extends the anagen (active growth) stage of the hair cycle and delays entry into the telogen resting phase, helping maintain stable hair density long-term.
- Perifollicular Collagen Regulation
Excessive collagen stiffening around hair follicles may lead to follicle fibrosis and progressive thinning. This ingredient helps soften perifollicular collagen, protecting follicle structure and maintaining normal physiological function.
Key Benefits of Kopexil in Hair Care
1. Superior Hair Growth Potential vs Minoxidil
A 2024 peer-reviewed animal study indexed in PubMed compared the efficacy of a 5% hydro-alcoholic solution containing Diaminopyrimidine Oxide with minoxidil over 28 days [1].
Key findings [1]:
- The Diaminopyrimidine Oxide group showed significant improvements in hair weight, follicle count, anagen hair ratio and overall hair growth compared with the minoxidil group.
- Higher expression of hair growth-related factors such as VEGF and HGF was detected in the Diaminopyrimidine Oxide treatment group.
- Toxicity tests showed no obvious differences in organ weight or morphological changes across groups, confirming good biocompatibility and safety.
The study confirmed that a 5% formula with this ingredient works as an effective hair growth stimulant, showing better overall performance and usability for cosmetic anti-hair loss applications [1].
2. Proven Real-World Efficacy
A large-scale international observational study enrolled 527 participants with mild androgenetic alopecia, using a professional scalp formula containing Diaminopyrimidine Oxide, arginine, and piroctone olamine [2].
Results after 3 months of consistent use [2]:
| Metric | Result |
|---|---|
| Overall hair loss reduction | 89.0% |
| Hair loss reduction (female) | 92.5% |
| Hair loss reduction (male) | 83.8% |
| Average user satisfaction score | 7.9 ± 1.7 |
| Good / very good skin tolerance | 98.6% |
The research verified that formulations containing this active ingredient effectively improve mild androgenetic alopecia for both men and women, with a pleasant texture and high user tolerance [2].
3. Excellent Skin Permeation & Formulation Stability
A 2026 peer-reviewed study evaluated the physicochemical properties, storage stability, and skin permeation capacity of Diaminopyrimidine Oxide compared with minoxidil [3].
Using HPLC detection and Franz diffusion cell testing, the data confirmed its superior transdermal permeation performance, helping active ingredients reach the follicle area more efficiently [3].
Stability tests show its formulations achieve a t90 shelf-life of 39–50 months under conventional storage conditions, providing long-term stability for commercial hair care products.
4. High Safety & Clear Regulatory Compliance
The 2023 Cosmetic Ingredient Review (CIR) final assessment classifies Diaminopyrimidine Oxide as safe for use in hair conditioning and scalp care cosmetics [4].
Global regulatory limits [4][5]:
- EU: Limited to max 1.5% in leave-on hair products
- China: Classified as a restricted cosmetic ingredient, maximum 1.5% in hair care formulations
- US: Allowed for cosmetic use at appropriate concentrations, not approved as a pharmaceutical drug
Animal safety studies also confirmed no obvious organ toxicity at usable concentrations. Compared with minoxidil, it avoids systemic side effects such as blood pressure fluctuation, making it safer for long-term cosmetic application.
5. Versatile Formulation Compatibility
High-purity Diaminopyrimidine Oxide powder is highly compatible for various hair care systems:
- Leave-on: Hair serums, scalp tonics, scalp lotions (0.5–1.5%)
- Rinse-off: Shampoos, conditioners (0.5–1.0%)
- Styling products: Hair gels, scalp sprays
It blends well with common cosmetic actives including piroctone olamine, caffeine, biotin, and plant extracts. Water solubility allows easy addition into aqueous formula phases without complex solubilization.
Why Choose Diaminopyrimidine Oxide Powder for Your Hair Care Formulations?
High‑purity Diaminopyrimidine Oxide powder offers significant advantages for cosmetic formulators and brand owners:
| Feature | Advantage |
|---|---|
| Scientifically validated efficacy | 89% hair loss reduction in clinical observation; outperforms minoxidil in animal trials |
| Better skin penetration | Higher transdermal delivery efficiency for improved bioavailability |
| Reliable safety profile | CIR confirmed safe; no obvious organ toxicity in published studies |
| Global regulatory compliance | Permitted up to 1.5% in EU and China cosmetic formulas |
| Long-term formulation stability | Shelf-life t90 up to 39–50 months under standard storage |
| Wide application flexibility | Suitable for shampoo, conditioner, serum, and scalp treatment |
When sourcing raw material, choose suppliers providing full COA, HPLC purity test (≥98%), heavy metal, residual solvent and microbiology reports for each batch.
Formulation Reference Dosage
Recommended addition ratio for cosmetic development:
- Hair serums & leave-on tonics: 0.5–1.5%
- Leave-on conditioners: 0.5–1.5%
- Hair styling gels & sprays: 0.5–1.5%
- Rinse-off shampoos: 0.5–1.0%
- Professional scalp treatment: 0.5–1.5%
Soluble in water, suitable for adding in the aqueous phase; stable within pH 4.0–7.0 and conventional production temperatures.
Conclusion
Diaminopyrimidine Oxide (industry common name: Kopexil) is a science-backed multifunctional cosmetic active for anti-hair loss and scalp care. It regulates DHT activity, improves scalp microcirculation, prolongs the hair growth cycle, and protects perifollicular tissue.
Supported by abundant animal experiments and real-user clinical data, it shows better hair growth performance and skin permeation than minoxidil, with a milder safety profile and clear global cosmetic regulatory permission.
For cosmetic brands and formulators, high-purity Diaminopyrimidine Oxide Powder is an ideal raw material for developing high-efficiency, safe, and market-competitive anti-hair loss and scalp care product lines.