FDA-Approved Intrathecal Drugs
Only three drugs have FDA approval for intrathecal administration: morphine (for chronic pain), ziconotide (for chronic pain), and baclofen (for spasticity). 1, 2, 3
Approved Agents for Chronic Pain Management
Morphine
- FDA-approved as monotherapy for intrathecal delivery in chronic pain 2, 3
- Preservative-free formulation required 4
- Acts as a μ-opioid receptor agonist
- Considered first-line therapy but requires careful patient selection due to risks of respiratory depression, withdrawal with pump malfunction, and tolerance development 3
Ziconotide (Prialt®)
- FDA-approved as the only non-opioid intrathecal analgesic for treatment-refractory chronic pain 2, 3, 5
- Synthetic conopeptide that selectively antagonizes N-type voltage-gated calcium channels 5
- Recommended as first-line therapy due to avoidance of opioid-related adverse effects 3, 4
- Contraindicated in patients with history of psychosis or allergy 4
- Primary tolerability concerns are CNS adverse events (mostly mild to moderate) 5
Baclofen
- FDA-approved for intrathecal use in spasticity management 1
- Not approved for pain management
Critical Clinical Context
Real-world practice differs dramatically from FDA approvals. In a large retrospective analysis of 32,784 patients, only 29.3% of all intrathecal prescriptions were for FDA-approved medications, and merely 7.9% used FDA-approved concentrations 1. The most commonly prescribed medications in actual practice were:
- Morphine (46.5% of opioid monotherapies)
- Hydromorphone (39.4% - off-label)
- Fentanyl (13.5% - off-label) 1
Combination therapy is common in practice (45% of prescriptions), though no combination therapies have FDA approval 1.
Important Caveats
- Off-label use of medications and drug combinations is frequently reported in pain management practice 2
- The obstetric anesthesia guidelines 6 describe intrathecal use of bupivacaine, levobupivacaine, ropivacaine, fentanyl, sufentanil, diamorphine, and morphine for labor analgesia and operative delivery - these represent different clinical contexts (acute procedural use) rather than chronic intrathecal drug delivery systems
- 16.7% of patients initially prescribed on-label formulations were subsequently switched to off-label concentrations or combinations to address clinical needs 1