Safe Prescribing of Muscle Relaxants with Fluvoxamine

Introduction to Safe Options

• The American College of Physicians recommends baclofen as the safest muscle relaxant to prescribe for patients taking fluvoxamine, as it does not have significant interactions with this SSRI medication 1
• Baclofen is metabolized primarily by deamination, not significantly affected by CYP450 inhibition, allowing for standard dosing starting with 5-10mg three times daily 1

Second-Line Options and Considerations

• Cyclobenzaprine can be considered as a second-line option if baclofen is not effective or not tolerated, but should be used with caution and at lower doses (starting at 5mg) due to potential for increased sedation 2
• The American Geriatrics Society recommends that elderly patients require dose reductions of muscle relaxants due to reduced clearance 3

Contraindications and Warnings

• Tizanidine is contraindicated with fluvoxamine due to significantly reduced clearance by inhibiting CYP1A2, leading to dangerous hypotension, bradycardia, and excessive sedation 3
• The American College of Emergency Physicians warns of an increased risk of respiratory depression when benzodiazepines are combined with other CNS depressants 4

Special Populations and Monitoring

• Patients with hepatic or renal dysfunction are at further increased risk of adverse effects with muscle relaxants 3
• Monitoring is necessary to watch for signs of excessive sedation, respiratory depression, or hypotension 4
• The American Academy of Emergency Medicine recommends avoiding co-prescribing opioids with muscle relaxants and SSRIs due to significantly increased risk of respiratory depression 4