Limitations and Future Directions
HP40 was found to be superior to vehicle for the treatment of raised SKs, but its efficacy is limited overall, producing complete clearance of all four SKs in only 4% and 8% of patients per study. As Bauman et al. discussed, patient satisfaction was not evaluated in the trials, and considering patients determine therapeutic success based on their appearances in the mirror rather than on physician-completed scales, superior results may have been observed with self-assessments. Regardless, patients still often require repeat treatments to produce adequate SK clearance (97% of the trial participants required second treatments), which can be cost prohibitive and time intensive for patients. HP40 is not covered by insurance and costs about $131 (US dollars) per treatment (as reported by The Medical Letter on Drugs and Therapeutics).
HP40 is also time consuming to apply for the dermatology clinic. In the clinical trials, treatment of four SKs took about 5 minutes and 20 seconds, and this time would be almost doubled for the average of seven SKs that can be treated with each HP40 pen. With four 20-second treatment cycles recommended per SK, this therapy is more time intensive than cryotherapy, which requires only 5 to 10 seconds of freezing for thin lesions. Thicker SKs may require an additional freeze-thaw cycle with cryotherapy, but this is still a shorter process than HP40 application. However, trained non-physician staff can also administer HP40, so practices can develop protocols to maximize application efficiency.
Skin Therapy Letter. 2020;25(1):1-4. © 2020 SkinCareGuide.com