Ticagrelor Dosing After Clopidogrel Discontinuation
Start with a 180 mg loading dose of Brilinta (ticagrelor) followed by 90 mg twice daily maintenance dosing, regardless of the two-week gap off clopidogrel. The patient can transition directly to ticagrelor without concern for the interruption in antiplatelet therapy 1.
Rationale for Loading Dose
The FDA label explicitly states that patients can be transitioned from clopidogrel to ticagrelor without interruption of antiplatelet effect 1. After two weeks off clopidogrel, the patient has essentially no residual platelet inhibition (clopidogrel's effects dissipate within 5-7 days), making this effectively a fresh start requiring full loading.
The 2017 ESC guidelines specifically address this scenario: switching from clopidogrel to ticagrelor is recommended at a loading dose of 180 mg irrespective of timing and loading dose of clopidogrel 2. This recommendation applies even when patients were previously exposed to clopidogrel, which clearly encompasses your patient's situation.
Standard Maintenance Dosing
Following the loading dose, prescribe 90 mg twice daily as the standard maintenance regimen 2. This dosing applies to:
- Patients with prior stent placement (as in your case)
- Patients with coronary artery disease requiring ongoing antiplatelet therapy
- Patients with abnormal coronary imaging findings
Clinical Context Considerations
Given the patient's history:
- Prior stent placement: Requires ongoing dual antiplatelet therapy (DAPT) with aspirin plus a P2Y12 inhibitor
- Abnormal coronary CTA: Suggests ongoing coronary disease requiring potent antiplatelet therapy
- Two-week gap: Creates urgency to reinitiate antiplatelet coverage
The ESC guidelines recommend ticagrelor over clopidogrel for patients with coronary artery disease, stating it should be used "unless the bleeding risk outweighs the potential ischemic benefit" 2.
Duration of Therapy
Continue ticagrelor for at least 12 months from the original stent placement if within that timeframe 2, 3. If beyond 12 months post-stent, continuation may still be reasonable given the abnormal CTA findings, particularly if the patient has no high bleeding risk factors 3.
Concomitant Aspirin
Prescribe aspirin 75-100 mg daily (typically 81 mg in the US) alongside ticagrelor 2, 3. This low-dose aspirin minimizes bleeding risk while maintaining antiplatelet efficacy.
Important Safety Considerations
Common pitfalls to avoid:
- Do NOT use a reduced 60 mg twice daily dose initially—this is only for specific long-term scenarios beyond 12 months post-ACS
- Do NOT skip the loading dose thinking residual clopidogrel effect remains after two weeks
- Do NOT use a 300 mg loading dose (this is insufficient)
Monitor for:
- Dyspnea: Occurs in up to 14% of patients on ticagrelor and is the most common reason for discontinuation
- Bradyarrhythmias: Rare but documented, including AV block 4
- Bleeding: Minor bleeding risk is increased compared to clopidogrel (OR 1.56) 5
Pharmacokinetic Reassurance
The FDA label confirms that ticagrelor reaches maximum platelet inhibition within approximately 2 hours of the loading dose, with maintained effect for at least 8 hours 1. This rapid onset makes it ideal for reinitiating antiplatelet therapy after a gap.
Add a proton pump inhibitor (PPI) to the regimen to reduce GI bleeding risk while on DAPT 2.