Here is a hypothetical Psoriasis Treatment Serum formulation:

Ingredients:

• Aqua (Water)
• Niacinamide (5%)
• Glycerin (5%)
• Propanediol (3%)
• Centella Asiatica Extract (3%)
• Aloe Vera Juice (2%)
• Sodium Ascorbyl Phosphate (Vitamin C, 2%)
• Tocopherol (Vitamin E, 1%)
• Zinc PCA (1%)
• Sodium Hyaluronate (1%)
• Xanthan Gum (1%)
• Phenoxyethanol (0.5%)

Instructions:

1. Begin by sterilizing all equipment and containers in accordance with good manufacturing practices.
2. Mix the niacinamide, glycerin, propanediol, and centella asiatica extract in a separate container until fully dissolved.
3. In another container, mix the aloe vera juice, sodium ascorbyl phosphate, tocopherol, and zinc PCA until fully dissolved.
4. Slowly add the water-soluble ingredients from step 2 to step 3, stirring constantly.
5. Stir in the sodium hyaluronate and xanthan gum.
6. Finally, add phenoxyethanol as a preservative and stir to fully incorporate.
7. Pour the mixture into a sterilized bottle and label it appropriately.

Note: This is a hypothetical formulation, and it is not intended for use or sale. The effectiveness and safety of this formulation have not been tested and it should not be used without proper consultation with a licensed healthcare professional or dermatologist. Additionally, it is important to always follow good manufacturing practices when making cosmetic products.

The ingredients in this formulation are believed to have beneficial properties for treating psoriasis, such as reducing inflammation and itching, improving skin hydration, and potentially lightening hyperpigmented areas. However, it is important to keep in mind that everyone's skin is unique, and what works for one person may not work for another. Always consult with a licensed healthcare professional or dermatologist before using any new cosmetic products, especially if you have a specific skin condition.