INTRODUCTION: Pre-exposure prophylaxis (PrEP) is highly effective in reducing the risk of HIV acquisition, but the population-level impact of PrEP depends on the proportion of people with PrEP indications who use it (coverage) and how long they stay on it while at risk (persistence). We aimed to assess the extent to which PrEP persistence varied by race/ethnicity, sex and age. METHODS: Previously reported methods and US commercial pharmacy data identified PrEP users and days covered. We calculated PrEP Days Covered (PDC) as the annual number of pills dispensed (i.e., pill-days) overall and by sex, race/ethnicity and age group. Statistical differences by demographic characteristics were calculated. To assess the potential impact of 2-1-1 PrEP dosing on median days of PrEP use, we compared 2018 and 2022 (pre- and post-US Public Health Service guideline for 2-1-1 dosing). RESULTS: There were 225,180 PrEP users in 2018, and 459,984 in 2022. In 2022, the median PDC was 167 (IQR: 67, 308). There were 90 versus 180 median PDC for female and male users, respectively (difference of 90 PDC, 95% CI, 89.6-90.4). Among PrEP users with race/ethnicity data, the median PDC was higher for White non-Hispanic (NH) (290 days) than Hispanic (268 days) or Black NH (251 days) users. Older users had significantly more PDC than younger users (<16 years: 60 days; 16-29 years: 120 days; 30-64 years: 191 days). Residents of states with PrEP-Drug Assistance Programs (PrEP-DAP) or Medicaid expansion had higher median PrEP duration than states without programmes. Median days covered for 2018 (154 days) and 2022 (167 days) did not suggest that the addition of the 2-1-1 PrEP guideline was associated with fewer covered days. CONCLUSIONS: PrEP programmes are often evaluated by enumerating people who used PrEP at any time during a year; our data indicate that significant differences in days of PrEP covered among users might mask further inequities in PrEP protection among women, and Black, Hispanic and younger people. Evaluations of PrEP equity should include a pharmacoequity component by assessing days covered as an additional indicator of PrEP equity.