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# Ticagrelor
## Overview
Ticagrelor is a reversible, non-thienopyridine $P2Y_{12}$ receptor antagonist that inhibits platelet activation and aggregation. Unlike clopidogrel, it does not require metabolic activation.
## Primary Indications
* Acute coronary syndrome (ACS): Reduction of thrombotic cardiovascular events.
* History of myocardial infarction (MI): Reduction of cardiovascular death, MI, and stroke in patients at high risk.
* Coronary artery disease (CAD): Prevention of ischemic events in patients with prior MI or high-risk features (in combination with aspirin).
## Adult Dosing
* **Loading Dose:** 180 mg PO once.
* **Maintenance Dose:** 90 mg PO twice daily for 12 months post-ACS; may reduce to 60 mg twice daily after 12 months for secondary prevention in high-risk patients.
* **Aspirin co-therapy:** Maintain aspirin dose at 75–100 mg daily. Higher maintenance doses of aspirin (>100 mg) decrease the efficacy of ticagrelor.
## Pediatric Dosing
Safety and efficacy have not been established in pediatric patients under 18 years of age. Use is generally avoided unless directed by institutional protocols for specific congenital heart conditions.
## Dose Adjustments
* **Renal Impairment:** No adjustment required.
* **Hepatic Impairment:** Contraindicated in patients with severe hepatic impairment. Use with caution in moderate impairment; no adjustment required for mild impairment.
## Contraindications
* Active pathological bleeding (e.g., peptic ulcer, intracranial hemorrhage).
* History of intracranial hemorrhage.
* Severe hepatic impairment.
* Known hypersensitivity to ticagrelor.
## Adverse Effects
* **Bleeding:** Major and minor bleeding (epistaxis, hematomas, GI bleed).
* **Dyspnea:** Very common (often transient, typically does not require discontinuation).
* **Bradyarrhythmia:** Ventricular pauses have been reported; monitor patients with pre-existing conduction abnormalities.
* **Hyperuricemia:** Increased serum uric acid levels.
## Key Drug Interactions
* **CYP3A4 Inhibitors (e.g., ketoconazole, clarithromycin, ritonavir):** Avoid concurrent use; may significantly increase ticagrelor concentrations.
* **CYP3A4 Inducers (e.g., rifampin, phenytoin, carbamazepine):** Avoid concurrent use; may significantly decrease efficacy.
* **Aspirin:** Maintain low-dose aspirin (≤100 mg).
* **Simvastatin/Lovastatin:** Limit dose to 40 mg daily due to increased risk of statin-related myopathy.
## Monitoring
* **Clinical:** Observe for signs/symptoms of bleeding (e.g., dark tarry stools, hemoptysis, unexplained bruising).
* **Laboratory:** Hemoglobin/hematocrit if bleeding is suspected.
* **Cardiac:** Monitor for dyspnea or symptoms of high-grade AV block, especially in the first week of therapy.
## Clinical Pearls
* **Reversibility:** Unlike clopidogrel and prasugrel, ticagrelor’s effect is reversible; platelets recover function within 3–5 days of discontinuation.
* **Surgery:** Discontinue at least 5 days prior to elective surgery to minimize bleeding risk.
* **Dyspnea Management:** If dyspnea is intolerable, consider switching to an alternative antiplatelet agent, but do not stop therapy prematurely post-ACS.
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**Disclaimer:** This information is for educational purposes and does not constitute medical advice. Always verify current prescribing information in a reputable clinical database (e.g., Lexicomp, UpToDate) and adhere to institutional protocols prior to prescribing or administering medication.
