Zinc Undecylenate: Technical Specifications and Pharmaceutical Utility

1. Technical Overview

Zinc Undecylenate, chemically known as Zinc 10-undecenoate ($[CH_2=CH(CH_2)_8COO]_2Zn$), is the zinc salt of Undecylenic acid. It is a fine, white, creamy powder recognized globally for its potent antifungal and antibacterial properties. While Undecylenic acid provides the primary fungistatic action, the zinc salt form is preferred in topical formulations due to its non-irritating nature and ability to reduce skin inflammation. In the pharmaceutical industry, it is a key active ingredient in over-the-counter (OTC) treatments for dermatomycoses, providing a synergistic effect when used in combination with free Undecylenic acid.

2. Chemical Structure & Composition

The molecular structure of Zinc Undecylenate consists of a central zinc ion coordinated with two undecylenate chains, each featuring a reactive terminal double bond.

• Molecular Weight: 431.94 g/mol.

• Zinc Content: Typically 14.5% to 15.5%.

• Purity: Manufactured to meet USP/BP pharmacopeia standards.

The presence of the terminal double bonds maintains the unique chemical signature of castor-derived undecylenates, ensuring high efficacy against fungal pathogens.

3. Physical & Chemical Properties

• Appearance: Fine, white to off-white, bulky powder.

• Odor: Faint, characteristic fatty odor (significantly milder than the free acid).

• Solubility: Practically insoluble in water and alcohol; soluble in chloroform and ether.

• Melting Point: 115°C to 121°C.

• Bulk Density: Low, providing excellent “slip” and spreadability in powder formulations.

4. Reaction Chemistry

Zinc Undecylenate functions primarily through its ionic dissociation and surface activity:

1. Fungistatic Mechanism: Upon contact with skin moisture, it slowly releases undecylenate ions which inhibit the growth and germination of fungal spores by disrupting cell membrane permeability.

2. Astringent Action: The zinc component provides a mild astringent effect, helping to dry out the affected area and reduce skin irritation (pruritus).

3. Thermal Stability: It remains stable during the manufacturing of ointments and creams that require heating up to 80°C.

5. When to Use vs. When NOT to Use

Use Zinc Undecylenate when:

• Formulating antifungal dusting powders (e.g., for Athlete’s Foot).

• Manufacturing topical ointments, creams, or aerosols for ringworm and diaper rash.

• Seeking a stable, non-volatile antifungal agent for specialized cosmetic formulations.

Do NOT use Zinc Undecylenate when:

• The application requires a clear liquid solution (as it is an insoluble powder).

• Formulating for deep-seated systemic fungal infections (it is strictly for topical use).

• The patient has a known hypersensitivity to zinc salts.

6. Compatibility Profile

• With Active Ingredients: Highly synergistic with Undecylenic Acid, Salicylic Acid, and Menthol.

• With Bases: Compatible with petrolatum, lanolin, talc, and starch-based carriers.

• Avoid: Strong oxidizing agents which may react with the terminal double bonds.

7. Manufacturing Process (Product Focus)

Nova Industries utilizes a precision precipitation process:

1. Neutralization: High-purity Undecylenic acid is reacted with a sodium base to form sodium undecylenate.

2. Precipitation: A solution of a high-purity zinc salt (such as zinc sulfate) is added to the sodium undecylenate solution under controlled pH and temperature.

3. Filtration & Washing: The resulting precipitate is filtered and washed extensively with deionized water to remove trace inorganic salts.

4. Micronization: The dried product is micronized to achieve a consistent, fine particle size for optimal formulation performance.

8. Technical Specifications Table

Parameter	Specification (USP/BP Grade)
Appearance	Fine White Powder
Zinc Content	14.5% – 15.5%
Identification	Positive for Zinc & Undecylenate
Loss on Drying	1.2% Max
Alkali & Alkaline Earths	1.0% Max
Free Undecylenic Acid	1.0% Max
Melting Point	115°C – 121°C

9. Quality Grade Analysis

Nova Industries focuses on the Freeness of Undecylenic Acid. While trace amounts are necessary for synergy, excessive free acid can cause a strong odor and skin irritation. Our process ensures the free acid is strictly controlled to meet pharmaceutical standards, providing a “user-friendly” powder with minimal odor.

10. Impact of Impurities

• High Moisture: Can lead to “clumping” of the powder, making it difficult to achieve a uniform blend in dusting powders.

• Alkali Salts: Residual salts from the precipitation process can cause skin stinging or grit in smooth ointments.

11. Industry-Wise Application 1: Foot Care (Athlete’s Foot)

Zinc Undecylenate is the standard active ingredient in antifungal foot powders. Its ability to absorb moisture while simultaneously killing fungal spores makes it highly effective for treating Tinea pedis.

12. Industry-Wise Application 2: Pediatric Care (Diaper Rash)

Due to its mild nature, it is used in specialized creams to treat diaper rash complicated by Candida infections. It provides a protective barrier while addressing the underlying fungal cause.

13. Industry-Wise Application 3: General Dermatology

Used in sprays and lotions for the treatment of ringworm (Tinea corporis) and jock itch (Tinea cruris). It is often preferred over synthetic antifungals for its long history of safety.

14. Industry-Wise Application 4: Industrial Preservatives

In some specialized coatings and adhesives, Zinc Undecylenate acts as a non-volatile biocide to prevent the growth of mold and mildew on the surface of the finished product.

15. Formulation Guide

• Powders: Usually blended at 10% to 20% concentration with talc or kaolin.

• Ointments: Incorporated into the oil phase. Typical formulations use a combination of 20% Zinc Undecylenate and 2% to 5% Undecylenic Acid for maximum efficacy.

16. Sustainability Data

Zinc Undecylenate is a bio-based derivative. It provides a sustainable, plant-derived alternative to synthetic antifungal agents, aligning with the “Clean Label” trends in pharmaceutical and cosmetic industries.

17. Packaging & Logistics (Technical)

• Standard: 25kg Corrugated boxes with double PE liners or Fiber Drums.

• Logistics: Classified as non-hazardous. Should be stored in a cool, dry place to prevent moisture absorption.

18. Storage Science

Must be stored in a well-closed container. It is physically stable but can absorb atmospheric moisture if left exposed. It should be kept away from direct sunlight to prevent any potential UV-induced cross-linking of the double bonds.

19. Troubleshooting Guide

• Problem: Grittiness in the ointment. Solution: Ensure the powder is properly micronized or pre-disperse it in a small amount of mineral oil before adding to the main batch.

• Problem: Off-odor in the formulation. Solution: Check the level of free Undecylenic acid; ensure the Zinc Undecylenate lot meets the <1% free acid specification.

20. Regulatory Compliance

Our Zinc Undecylenate is REACH Compliant and manufactured in facilities following GMP-aware protocols. It meets the monograph requirements of the USP (United States Pharmacopeia) and BP (British Pharmacopeia).

21. Safety (SDS Summary)

• Handling: Use a dust mask and gloves. Avoid inhalation of the fine powder.

• Toxicity: Very low acute toxicity; considered safe for topical application at recommended levels.

• Environment: Do not dispose of large quantities into the aquatic environment.

22. Sample Validation Process

Verify the Zinc Content and Loss on Drying. For pharmaceutical use, a “Microbial Limit Test” and assay for free undecylenic acid are essential.

23. Commercial Efficiency

By sourcing micronized Zinc Undecylenate from Nova Industries, manufacturers can reduce their processing time (milling) and achieve a more homogenous mix in their final products, leading to fewer batch failures and higher consumer satisfaction.

24. Technical FAQs

1. Is Zinc Undecylenate better than the free acid? It is less irritating and more stable in powder forms, but they are often used together for the best results.

2. Is it 100% bio-based? The undecylenate part is 100% bio-based (from castor oil); the zinc is a mineral component.

3. Does it have a shelf life? It is stable for 3–5 years if stored correctly in a dry environment.

25. Contact CTA

For Technical Data Sheets (TDS), Pharmacopeia Compliance Certificates, or to request a sample, please contact our export division at: export@novaind.in