Background and aims Intrathecal route is a safe and efficient option for chronic pain treatment. It delivers a more selective analgesia with fewer doses and fewer selective adverse side effects.

Intrathecal fentanyl was recommended by the 2016 Polyanalgesic Consensus Conference (PACC) if first line intrathecal therapy with FDA approved drugs failed.

The aim of our study was analysing patient data treated with intrathecal fentanyl in our pain unit, in order to establish a safe and efficient dose protocol.

Methods We reviewed the clinical history of the 25 patients treated with intrathecal fentanyl. We gathered diagnosis and different aspects of the therapy: infusion technic and apparatus, initial doses, maximum recorded doses and adverse side effects, among others.

Results The most frequent diagnosis was failed back syndrome. Medtronic Sinchromed II was the employed infusion apparatus, without dosification errors. Continuous infusion was performed in all cases. The test phase lasted 16 days on average with initial doses ranging from 20 to 175 mcg/day. The maximum dose was 1.100 mcg/day without any adverse effect.

Conclusions The main advantages of fentanyl over morphine are an easier dose adjustment and its lesser risk of granuloma formation, tolerance development and supraspinal adverse side effects. Intrathecal dosification precision is crucial for patient’s safety. Medtronic Syncromed II system showed some precision issues with non-approved drugs and combined therapies. Nevertheless, in our study there were no incidents whatsoever. We employed continuous infusion from the test phase on, with a conservative dosification strategy based on low initial doses with progressive and continuous increase, yielding satisfactory results.