40 SUN CARE
twelve formulations with and without aqueous TiO2
has much higher in vitro SPF results than
Figure 1 also shows the in vitro results of the dispersion along with the expected
theoretical values. As can be seen in Figure 1 the in vitro results for all the systems with aqueous TiO2
were predicted and thus could be representing the synergistic effect between the two types of UV filters.
In vivo SPF & in vitro UVAPF evaluation Another study was conducted whereby three formulations were made and sent for in vivo SPF and in vitro UVAPF testing which can be seen in Table 8. The three formulations were the same besides the UV filter combinations. One was made with just organic UV filters, the second with inorganic UV filters only and the third contained a combination of organic and inorganic UV filters. Once made, these formulations were sent off for external in vivo SPF and internal in vitro UVAPF testing and the results can be seen in Figure 2. As you can see in Figure 2, there is a clear
increase of in vivo SPF and in vitro UVAPF when organic and inorganic UV filters are combined compared to when they are used separately which again may be indicative of the synergy effect between both types of UV filters.
Discussion As seen in the two sets of results, our studies both in vitro and in vivo, have found that when a combination of aqueous TiO2 dispersion is added alongside organic UV filters, there is a significant increase in SPF and UVAPF units when tested compared to the same system that did not use a combination of UV filters. It is thought that this is down to the synergy effect and possibly the presence of UV filters in both phases of an emulsion resulting in an SPF boost since they are fully present and distributed in both phases. Other referenced studies have used the
Monte Carlo calculation to prove this theory by using typical optical parameters of the skin to characterise the synergy effect when organic and inorganic UV filters are used together. They proved that the synergistic effect is caused by light scattering from inorganic UV filters in combination with organic UV filters.1
in Figure 3. As discussed, aqueous TiO2
recommended due to the lack of interaction with organic UV filters. There are many variations of aqueous TiO2
dispersions with
smaller or larger particle sizes, which will ultimately affect the formulation in terms of the transparency on the skin and the range of UVA and UVB protection. The benefits of using these aqueous dispersions is that they give great synergy, along with formulation flexibility. While formulating, it is important to
keep in mind that some combinations of organic and inorganic UV filters are not desirable such as the combination of butyl methoxydibenzoylmethane (BMDM) with TiO2
. This is because BMDM is known to PERSONAL CARE October 2021 B Organic only■ Theorethical expected ■ Combined system ■
80 70 60 50 40 30 20 10 0
Emulsifier A Emulsifier B Emulsifier C Emulsifier D Emulsifier E dispersion) Emulsifier F
Figure 1: In vitro SPF of formulations with different O/W emulsifiers & two UV filter systems (organic UV filters only & organic UV filters with aqueous TiO2
TABLE 2: FORMULATIONS USING EMULSIFIER B Phase A
Ingredients Aqua
Glycerin Xanthan Gum
Magnesium Aluminium Silicate Aqueous TiO2
B C
Potassium Cetyl Phosphate C12-15 Alkyl Benzoate
Decyl Isostearate (and) Isostearyl Isostearate Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine Ethylhexyl Salicylate
D
Butyl Methoxydibenzoylmethane Octocrylene Preservative
TABLE 3: FORMULATIONS USING EMULSIFIER C Phase A
Ingredients Aqua
Glycerin Xanthan Gum
Magnesium Aluminium Silicate Aqueous TiO2
B C12-15 Alkyl Benzoate
Decyl Isostearate (and) Isostearyl Isostearate Polyglyceryl-4 Laurate/Succinate (and) Aqua Sorbitan Stearate
C
Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine Ethylhexyl Salicylate
D
This theory is demonstrated dispersion is
Butyl Methoxydibenzoylmethane Octocrylene Preservative
TABLE 4: FORMULATIONS USING EMULSIFIER D Phase A
Ingredients Aqua
Glycerin Xanthan Gum
Magnesium Aluminium Silicate Aqueous TiO2
C12-15 Alkyl Benzoate
Decyl Isostearate (and) Isostearyl Isostearate Polyglyceryl-4 Laurate/Succinate (and) Aqua Sorbitan Stearate
C
Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine Ethylhexyl Salicylate
D
Butyl Methoxydibenzoylmethane Octocrylene Preservative
Organic only Up to 100 3.00 0.20 0.80 –
3.50
10.00 5.00 2.00 5.00 2.00 8.00 0.80
Organic only Up to 100 3.00 0.20 0.80 –
10.00 5.00 2.67 3.40 2.00 5.00 2.00 8.00 0.80
Organic only Up to 100 3.00 0.20 0.80 –
10.00 5.00 2.46 3.04 2.00 5.00 2.00 8.00 0.80
Organic + aqueous TiO2 Up to 100 3.00 0.20 0.80 7.00 3.50
10.00 5.00 2.00 5.00 2.00 8.00 0.80
Organic + Aqueous TiO2 Up to 100 3.00 0.20 0.80 7.00
10.00 5.00 2.67 3.40 2.00 5.00 2.00 8.00 0.80
Organic + Aqueous TiO2 Up to 100 3.00 0.20
0.80 –
10.00 5.00 2.46 3.04 2.00 5.00 2.00 8.00 0.80
www.personalcaremagazine.com
In-vitro SPF
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92
