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# Ticagrelor
## Overview
Ticagrelor is a reversible, non-thienopyridine P2Y12 platelet inhibitor that prevents ADP-mediated activation of the GPIIb/IIIa receptor complex. Unlike clopidogrel, it does not require metabolic activation.
## Primary Indications
* Acute coronary syndrome (ACS): Unstable angina, NSTEMI, and STEMI.
* Secondary prevention of cardiovascular events in patients with a history of MI.
* History of coronary artery disease (CAD) in high-risk patients.
## Adult Dosing
* **Loading Dose:** 180 mg orally once.
* **Maintenance Dose:** 90 mg orally twice daily for the first 12 months post-ACS.
* **Long-term Secondary Prevention (after 12 months):** May reduce to 60 mg orally twice daily if the patient is at high risk of recurrent ischemic events.
* **Coronary Artery Disease (High Risk):** 60 mg twice daily chronically.
## Pediatric Dosing
There is no FDA-approved pediatric indication. Use is off-label and generally restricted to specialized pediatric cardiology settings (e.g., Kawasaki disease or specialized thrombotic conditions) under strict institutional protocol.
## Dose Adjustments
* **Renal Impairment:** No dose adjustment required.
* **Hepatic Impairment:** Avoid in severe hepatic impairment. Use with caution in moderate impairment (no specific dose adjustment provided in labeling, but monitor for bleeding).
* **CYP3A4 Interactions:** Dose adjustments may be required when co-administered with strong inhibitors or inducers.
## Contraindications
* Active pathological bleeding (e.g., peptic ulcer, intracranial hemorrhage).
* History of intracranial hemorrhage.
* Severe hepatic impairment.
* Known hypersensitivity to ticagrelor.
* Pre-operative setting for coronary artery bypass graft (CABG) surgery (discontinue at least 5 days prior).
## Adverse Effects
* **Bleeding:** Major and minor hemorrhage (epistaxis, hematuria, gastrointestinal).
* **Dyspnea:** Very common; usually transient and mild-to-moderate; rarely requires discontinuation.
* **Bradyarrhythmias:** Ventricular pauses reported during the first week of therapy.
* **Hyperuricemia:** May increase serum uric acid levels.
## Key Drug Interactions
* **Strong CYP3A4 Inhibitors (e.g., Ketoconazole, Clarithromycin, Ritonavir):** Avoid concurrent use; significantly increases ticagrelor levels.
* **Strong CYP3A4 Inducers (e.g., Rifampin, Phenytoin):** Avoid concurrent use; significantly reduces ticagrelor efficacy.
* **Aspirin:** Maintenance doses >100 mg daily reduce the efficacy of ticagrelor.
* **Simvastatin/Lovastatin:** Limit dose to 40 mg daily due to increased risk of statin-related myopathy.
## Monitoring
* **Clinical:** Observe for signs of bleeding (bruising, occult stool blood, melena).
* **Labs:** Baseline and periodic CBC (hemoglobin/hematocrit) is recommended. Monitor serum creatinine and uric acid if clinically indicated.
* **Cardiac:** ECG monitoring during the first week if the patient is at risk for bradycardia.
## Clinical Pearls
* **Reversibility:** Unlike clopidogrel and prasugrel, ticagrelor's inhibition is reversible. Platelet function recovers faster post-discontinuation compared to thienopyridines.
* **Compliance:** BID dosing is required; missed doses increase the risk of thrombotic events.
* **Dyspnea Differentiation:** Educate patients that dyspnea is a known side effect and usually dose-independent; ensure it is not mistaken for worsening cardiac status.
* **Switching:** If switching from clopidogrel, administer the 180 mg loading dose immediately after the last clopidogrel dose.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical protocols may vary by institution. Always verify dosages, contraindications, and drug interactions using current, peer-reviewed clinical databases (e.g., Lexicomp, UpToDate) and local institutional guidelines before prescribing or administering medication.
