so when the user wants to remove the nail gel coating it will not require excessive efforts. This technology teaches that if one uses a photopolymerizable cellulose ester as the ‘Achilles heel’ then removal should require far less effort than what is traditionally needed. As can be seen in Table 3.9 the use of the photopolymerizable cellulose ester in a potential UV nail gel application results in a coating after UV curing that shows solubility in the acetone soak yet still retains the MEK (Methyl Ethyl Ketone) double rubs needed from a performance aspect.
Other formulations in Table 3.9 have higher crosslinking but would require much removal efforts. Unfortunately, all of this work was done using high performance UV cure light technology that we have described earlier and would need to be reformulated to meet the needs of the lower UV energy GA-FL and LED UV cure light technology [24]. Another approach for the removal of UV cure nail gels is the use of an alkoxylated lanolin oil and acetone. The art taught in this recent patent claims that this system based on 2.5% alkoxylated lanolin oil in acetone was able to remove UV cure nail gel within 168 seconds (2.8 minutes) [25].
3.11 Alternative Uses of UV Cured Nail Gels as a Solution to Remedy Onychomycosis (Toenail Fungus)
Up until this point our discussion has centered around the beautification of the human nail by way of UV nail gel. An alternative technique has been developed that would allow the UV nail gel to be the carrier for transporting drugs that are needed to treat certain toenail diseases such as onychomycosis.
Researchers [26] in this case utilized the Curanail coating (32 wt.% Amorolfine HCl UV-cured coating), 3 wt.%. Amorolfine HCl UV-cured coating, and 4 wt.%. Terbinafine HCL UV-cured coating as shown in Table 3.10. The study was carried out using human nail secured from patients ages 18 to 65 years. The permeation study was carried out and the results are shown in Table 3.10 whereby all anti-onychomycotic drugs penetrated the nail plate delivering the agent to terminate the fungus. The major benefit here is the long residence time that the anti-onychomycotic drug is able to stay on the nail plate delivering it over a long period of time. It is obvious that other traditional topical therapy would not last as long due to the environment that the nail plate resides in [26].
Table 3.9 Photopolymerizable cellulose esters that act as the ‘Achilles heel’ in the UV cure nail gel polymer allowing easy removal of the coating by acetone soak yet maintaining MEK double rub performance. The acetone solubility test is carried out by immersing a dry, pre-weighed sample of the coating in acetone for 48 hours at 25°C. The coating is removed, dried for 16 hours at 60°C in a forced-air oven, and reweighed. The weight percent of the insoluble coating remaining is calculated from the data.
| Cellulose Ester Type | Pencil Hardness | Acetone Insolubles Wt.% Film Recovery | MEK Double Rubs |
| CA 320S (Control)1 | F | 0 | <10 |
| CAP 504 (Control)1 | HB | 0 | <10 |
| CAB 553 (Control)1 | 2B | 0 | <10 |
| Nitrocellulose (RS ½ sec.)1 | 3B | 0 | <10 |
| CA Maleate (0.32 DS) | H/2H | 94 | >200 |
| Sample 1 | |||
| CAP Maleate (0.10 DS) | F | 42 | 98 |
| Sample 2 | |||
| CAP Maleate (0.25 DS) | H | 90 | >200 |
| Sample 3 | |||
| CAP Maleate (0.39 DS) | H/2H | 94 | >200 |
| Sample 4 | |||
| CAP Maleate (0.46 DS) | H | 91 | >200 |
| Sample | |||
| CAB Maleate (0.41 DS) | H/F | 92 | >200 |
| Sample 6 | |||
| CAP Methacrylate (0.52 DS) | H/F | 31 | 91 |
| Sample 7 | |||
| CAP Acrylate (0.25 DS) | F | 43 | 62 |
| Sample 8 | |||
| CAB Methacrylate (0.40 DS) | F | 48 | 109 |
| Sample 9 | |||
| CAB Acrylate (0.20 DS) | F | 29 | 41 |
| Sample 10 | |||
| CAP TMI (0.59 DS) | 2H | 82 | >200 |
| Methacrylate (0.30 DS) | |||
| Sample 11 | |||
| CAB TMI (0.62 DS) | H | 88 | >200 |
| Methacrylate (0.2 DS) | |||
| Sample 12 | |||
Sample 8 (CAP Acrylate (0.25) might be a good candidate for GAL-FL or LED. (Control)1: Not formulated, (DS): degree of substitution per glucose ring.
