Ticlopidine
Ticlid
First-generation thienopyridine P2Y12 inhibitor (irreversible)
Irreversibly blocks P2Y12. Largely replaced by clopidogrel due to hematologic toxicity.
Indications
- •Antiplatelet therapy when clopidogrel not tolerated (rare now)
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Maintenance | 250 mg PO BID | — |
Pharmacokinetics
Onset delayed (peak effect days). Irreversible — effect lasts ~10 days.
Side effects
- !Neutropenia/agranulocytosis
- !TTP
- !Bleeding
- !Requires CBC monitoring
Contraindications
- ×Neutropenia/thrombocytopenia
- ×Active bleeding
Clinical pearls
- ★ASRA neuraxial: hold 10 days (longest of the oral antiplatelets).
- ★Rarely used now — hematologic toxicity (neutropenia, TTP) drove the switch to clopidogrel.
Other drugs in Antiplatelets
- Aspirin
Irreversibly acetylates COX-1 → blocks thromboxane A2 for the platelet's lifespan (~7–10 days). Antiplatelet effect at low dose; analgesic/anti-inflammatory at high dose.
- Clopidogrel
Prodrug → active metabolite (CYP2C19) irreversibly blocks the platelet P2Y12 ADP receptor for the platelet lifespan.
- Prasugrel
Prodrug → active metabolite irreversibly blocks P2Y12. More potent + more consistent than clopidogrel (not CYP2C19-limited), but more bleeding.
- Ticagrelor
Directly and REVERSIBLY inhibits P2Y12 (not a prodrug, not thienopyridine). Faster onset/offset than clopidogrel.
- Abciximab
Fab fragment that irreversibly blocks the platelet GP IIb/IIIa receptor → prevents fibrinogen cross-linking (final common pathway of aggregation).
- Eptifibatide
Reversibly blocks GP IIb/IIIa (final common pathway of platelet aggregation). Short-acting.
- Dipyridamole
Inhibits platelet PDE (↑ cAMP) and adenosine reuptake (↑ adenosine → vasodilation). Weak antiplatelet; also a coronary vasodilator used in stress testing.
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
- •ASRA regional anesthesia in the anticoagulated patient guidelines, 2018
