When should cilostazol be discontinued before performing neuraxial or deep peripheral nerve block (regional anaesthesia)?

Cilostazol Discontinuation Before Regional Anaesthesia

Cilostazol should be discontinued for 42 hours (approximately 2 days) before performing neuraxial blockade or deep peripheral nerve blocks to allow adequate clearance based on its 11-hour elimination half-life and antiplatelet effects.

Pharmacokinetic Rationale

The discontinuation timing is calculated from cilostazol's pharmacokinetic profile:

• Elimination half-life: Cilostazol has an apparent elimination half-life of approximately 11 hours in both healthy volunteers and patients with peripheral arterial disease 1
• Time to normal platelet function: Using the standard formula of time to peak effect + (elimination half-life × 2), cilostazol requires approximately 42 hours for adequate drug clearance 1
• Peak plasma concentration: Occurs approximately 3 hours after oral administration, with detectable plasma levels persisting for at least 36 hours post-dose 1

Risk-Stratified Approach by Block Type

High-Risk Neuraxial Blocks (Spinal/Epidural)

• Discontinue cilostazol 42 hours (2 days) before the procedure to ensure platelet function has normalized 2, 1
• Extend to 48 hours if traumatic needle placement is anticipated or in patients with additional bleeding risk factors 2
• Catheter techniques carry higher risk than single-shot blocks, and the same precautions apply to catheter removal as to initial placement 2

Deep Peripheral Nerve Blocks

Deep blocks where bleeding cannot be compressed (infraclavicular brachial, para-sacral sciatic, posterior lumbar plexus) should follow the same 42-hour discontinuation period as neuraxial blocks 2. These blocks are high-risk because:

• Compression is not possible if bleeding occurs 2
• Potential for serious complications including exsanguination, airway obstruction, or vascular occlusion 2
• One reported death occurred in a patient on clopidogrel (another antiplatelet agent) who underwent lumbar plexus block and exsanguinated 2

Low-Risk Superficial Blocks

Superficial blocks where bleeding is easily compressible (femoral nerve, axillary plexus, popliteal sciatic) may be performed with shorter discontinuation periods or potentially without discontinuation if the benefit-risk ratio is favorable, though specific timing for cilostazol is not established in guidelines 2.

Critical Safety Considerations

Patient-Specific Risk Factors

The following factors increase bleeding risk and may warrant extending the discontinuation period beyond 42 hours 3:

• Advanced age, particularly elderly females
• Renal or hepatic impairment (cilostazol is contraindicated in severe impairment, but moderate dysfunction may prolong drug clearance) 4
• Concomitant antiplatelet or anticoagulant therapy (aspirin, NSAIDs, warfarin, or other agents) 4, 5
• CYP3A4 or CYP2C19 inhibitors (erythromycin, diltiazem, omeprazole) which increase cilostazol levels 4
• Spinal cord or vertebral column abnormalities
• Traumatic or difficult needle placement 2

Warning Signs of Spinal Hematoma

After any neuraxial procedure in patients who have taken cilostazol, monitor for 6:

• New midline back pain
• Progressive neurological deficits (motor or sensory)
• Bowel or bladder dysfunction

Immediate MRI is mandatory if any of these signs develop, as epidural hematoma must be evacuated within 8-12 hours to prevent irreversible neurological injury 7, 8.

Resumption After Regional Anaesthesia

• Wait at least 6 hours after catheter removal before restarting cilostazol, provided adequate hemostasis has been achieved 2
• Extend to 24 hours if needle/catheter placement was traumatic (bloody tap) 8
• Document complete resolution of motor block using the Bromage scale before catheter removal 7
• Perform neurological examination 4 hours after catheter removal including straight-leg raise testing 7, 8

Common Pitfalls to Avoid

• Do not confuse cilostazol with other antiplatelet agents: Unlike aspirin or NSAIDs which require no additional precautions for neuraxial blocks, cilostazol requires a 42-hour hold similar to P2Y12 inhibitors (clopidogrel requires 7 days, but cilostazol's shorter half-life allows shorter discontinuation) 2, 1
• Do not assume cilostazol is safe because bleeding studies showed no increase: The CASTLE study showed no increased serious bleeding events with cilostazol, but this was in general populations, not specifically for neuraxial procedures where even small bleeds can be catastrophic 5
• Do not restart cilostazol too early after high-risk procedures: For major surgery with ongoing bleeding risk, consider delaying resumption for 48-72 hours 7
• Account for drug interactions: Patients on CYP3A4 or CYP2C19 inhibitors may have prolonged cilostazol levels requiring extended discontinuation 4

Documentation Requirements

• Record exact time of last cilostazol dose
• Document cilostazol dose and any interacting medications
• Note time of needle/catheter placement and removal
• Document 4-hour post-procedure neurological examination
• Obtain informed consent addressing increased bleeding risk 7, 8