OBJECTIVES: The inappropriate use of carisoprodol has been increasing in the US, and abuse of this substance poses an overdose risk which may lead to death. Beginning 1^st March 2020, Texas mandated prescribers and pharmacists to review the Prescription Monitoring Program (PMP) database before issuing selected controlled substances, including carisoprodol, to patients. However, the impact of this regulation on dispensing carisoprodol is unknown. This study aimed to examine whether the Texas PMP Mandate was associated with changes in carisoprodol dispensing in Texas.

METHODS: Counts of carisoprodol prescriptions, patients filling, prescribers, and dispensaries were computed monthly from March 2019 to March 2021 using the Texas PMP database. Changes in the monthly count of patients, prescriptions, prescribers, and dispensaries before and after March 1, 2020, were estimated using autoregressive interrupted time series regression.

RESULTS: In the pre-implementation period, there was a significant and sustained decrease in monthly counts of patients filling carisoprodol prescriptions (β = -581.6, P < 0.001); carisoprodol prescriptions (β = -626.7, P < 0.001), and prescribers (β = -67.9, P < 0.001), and dispensaries (β = -16.5, P = 0.004). The mandate resulted in an immediate but not statistically significant decrease in the counts for prescribers and dispensaries (P>0.05). Compared to the baseline, there was an increase in the number of patients filling carisoprodol (β=370.0, P=0.004), carisoprodol prescriptions (β=393.1, P<0.01), and prescribers (β=27.6, P=0.0469) post-implementation, resulting in a net decrease in carisoprodol-related activities at the rates of 211 patients, 233 prescriptions, and 40 prescribers per month respectively.

CONCLUSIONS: There is no sufficient evidence for the associations between the Texas PMP mandate and changes in carisoprodol prescribing and dispensing. Future research is warranted to continuously monitor the trend in carisoprodol dispensing and explore factors that may hinder the adoption of the PMP mandate by prescribers and dispensers in Texas.