Formulation and Alcohol-Free Alternatives for Mouth Odor Spray
Question
I am looking for advice on a mouth odor spray formulation. I found the following formula and would like to know about its suitability, stability, and potential improvements:
Original Formulation:
Ethyl Alcohol (99.9%): 20%Propylene Glycol: 5%Poloxamer 407: 1%DeoMax™ Liquid: 1%Four-EO: 0.3%Zinc Citrate: 0.2%Cetylpyridinium chloride: 0.01%Water: balance to 100%
Specifically, I have the following questions:
- Is this formula effective and stable for an oral spray application?
- If I want to avoid using
Ethyl Alcoholto prevent a burning sensation or dryness, what alternative solvents or bases should I use? - How should I adjust the formula (e.g., solubilizers or preservatives) when removing the alcohol to maintain efficacy, stability, and safety?
Answer
Review of the Original Formula
The mouth spray formula you provided is fundamentally sound and uses effective ingredients for combating bad breath:
- Efficacy: The combination of Zinc Citrate (to neutralize volatile sulfur compounds) and Cetylpyridinium chloride (CPC) (an antiseptic) is excellent for a dual-action anti-odor effect. DeoMax™ Liquid and Four-EO™ provide immediate freshness and masking.
- Concentrations: The concentrations of the active ingredients are appropriate for an oral spray. The 0.01% CPC is safe and effective for this application.
- Stability Concern: The primary concern is the stability of the non-polar ingredients (DeoMax™ Liquid and Four-EO™) in the base. While Poloxamer 407 (1%) is the solubilizer, this concentration might be too low to fully dissolve 1.3% of non-polar ingredients (1% DeoMax + 0.3% Four-EO) in a 20% alcohol/water base. Recommendation: Always test the final product for clarity and stability. If cloudiness or separation occurs, increase the Poloxamer 407 concentration.
Alcohol-Free Alternative (Replacing Ethyl Alcohol)
To avoid the burning sensation and dryness associated with 20% Ethyl Alcohol, you can replace it with a combination of oral-safe glycols and adjust the solubilizer:
Solvent/Base Replacement: Replace the 20% Ethyl Alcohol with a blend of Glycerin (USP/Food Grade) and Propylene Glycol (USP). This maintains solvency, improves the mouthfeel, and adds a pleasant sweetness.
- Original Formula: 20% Ethyl Alcohol + 5% Propylene Glycol
- Revised Base: 10% Glycerin (USP/Food Grade) + 15% Propylene Glycol (USP) (Total 25% co-solvent, replacing 25% of the original base).
Solubilizer Adjustment: Since alcohol is a strong solvent, removing it requires increasing the primary solubilizer.
- Increase Poloxamer 407 from 1% to 2-3% to ensure the DeoMax™ Liquid and Four-EO™ remain fully dissolved and the spray is clear and stable.
Preservation: The 20% alcohol provided significant preservation. When removing it, a dedicated oral-safe preservative system is essential.
- Recommendation: Use a combination of Potassium Sorbate (0.1-0.2%) and Sodium Benzoate (0.1-0.2%), which are common and safe for oral care products, or another suitable broad-spectrum preservative.
Revised Alcohol-Free Formula
| Ingredient | Function | Suggested % |
|---|---|---|
| Water | Base | Balance (approx. 70%) |
| Glycerin (USP/Food Grade) | Co-solvent, Humectant, Sweetener | 10.0% |
| Propylene Glycol (USP) | Co-solvent, Humectant | 15.0% |
| Poloxamer 407 | Solubilizer | 2.0 - 3.0% |
| DeoMax™ Liquid | Odor Absorber | 1.0% |
| Four-EO™ | Flavor/Essential Oil | 0.3% |
| Zinc Citrate | Anti-Odor Active | 0.2% |
| Cetylpyridinium chloride (CPC) | Antiseptic | 0.01% |
| Preservative (e.g., Sorbate/Benzoate) | Preservation | 0.2 - 0.4% |
Note: Always check the pH of the final product. Zinc Citrate works best in a slightly acidic environment (pH 5.5-6.5). Adjust the pH if necessary.
Related Products Mentioned
Propylene Glycol (USP)
Glycerin (USP/Food Grade)
Four-EO™
Cetylpyridinium chloride (CPC)
