Prescription Patterns of Adjuvant Pain Medications Following an Opioid Supply Restriction Law: An Interrupted Time Series Analysis.

Background: Florida House Bill 21 (HB21) was implemented in July 2018 to limit prescriptions of Schedule II opioids for acute pain patients, but it is unclear whether such restrictions have a collateral influence on the utilization of commonly prescribed adjuvant pain medications.

Objective: The objective of this study was to assess whether this law was associated with a change in use patterns of gabapentinoids, benzodiazepines, and muscle relaxants.

Methods: We obtained prescription claims for medications dispensed from January 1, 2015, to June 31, 2019, from a health plan serving a large Florida employer. Interrupted time series analyses were conducted to compare pre-HB21 and post-HB21 implementation changes in the mean monthly number of users and prescriptions for gabapentinoids, benzodiazepines, and muscle relaxants.

Results: There was a 6% immediate increase (relative risk: 1.06; 95% confidence interval: 1.02, 1.11) in the monthly proportion of gabapentinoid users, and an 11% immediate increase in the monthly proportion of gabapentinoids prescriptions (relative risk: 1.11; 95% confidence interval: 1.04, 1.18) per 1000 patients following law implementation. However, after the law, we observed a significant reduction in trend for the monthly proportion of muscle relaxants and benzodiazepine users.

Conclusions: An increased number of patients and prescriptions were observed for gabapentinoids, while fewer patients received benzodiazepines and muscle relaxants after HB21. In previous studies, opioid prescription restriction laws are shown to reduce opioids, but this work suggests that these laws may also have unintended consequences for the use of adjunctive medications that were not intended to be affected.