# Evolution of Fentanyl Prescription Patterns and Administration Routes in Primary Care in Salamanca, Spain: A Comprehensive Analysis from 2011 to 2022

## TL;DR

This study tracks how fentanyl prescriptions in Spain's Salamanca region doubled from 2011 to 2022, mainly through skin patches, and compares it to national and US trends.

## Contribution

The study provides a detailed analysis of fentanyl prescription trends in Salamanca, Spain, highlighting administration route preferences and comparing them to national and international data.

## Key findings

- Fentanyl use in Salamanca doubled from 1.21 to 2.56 DHD between 2011 and 2022.
- Transdermal systems were the most common administration route for fentanyl prescriptions.
- Fentanyl consumption in Spain increased less than in the US, possibly due to inappropriate prescriptions for non-cancer pain.

## Abstract

(1) Background: The escalating use of opioids contributes to social, health, and economic crises. In Spain, a notable surge in the medical prescription of opioids in recent years has been observed. The aim of this work was to assess the consumption rate of fentanyl, categorised by the different administration routes, in Primary Care in the province of Salamanca (Spain) spanning the years 2011 to 2022, and to compare it with the national trend and with data from the US. (2) Methods: Doses per inhabitant per day (DHD) were calculated, and interannual variations, as well as consumption rates, were subject to thorough analysis. (3) Results: The prevalence of fentanyl use in Salamanca has doubled from 1.21 DHD in 2011 to 2.56 DHD in 2022, with the transdermal system (TD) as the predominant administration route. This upward trajectory mirrors the national trend, yet the rise in fentanyl use is markedly lower than the reported data in the US. This finding may be attributed to an ageing population and potentially inappropriate fentanyl prescriptions, i.e., for the management of chronic non-cancer pain and other off-label prescriptions. (4) Conclusions: The use of fentanyl in Salamanca, particularly through transdermal systems, doubled from 2011 to 2022, aligning with the national trend. Preventive measures are imperative to prevent fentanyl misuse and moderate the observed escalation in consumption rates.