Table 1.
Comparison of platelet inhibitors.
| Aspirin | Clopidogrel | Prasugrel | Ticagrelor | Vorapaxar | |
|---|---|---|---|---|---|
| Target | COX-1 enzyme | P2Y12 receptor | P2Y12 receptor | P2Y12 receptor | PAR-1 receptor |
| Class | Acetyl salicylic acid | Thienopyridine | Thienopyridine | CTPT | Himbacine analogue |
| Metabolism | Direct drug | Prodrug | Prodrug | Direct drug | Direct drug |
| Administration | Oral | Oral | Oral | Oral | Oral |
| Metabolic pathway | Hepatic (salicylic acid) | Hepatic CYP P450 (1A2, 2C19, 3A4/5, 2B6, 2C9) | Intestine/hepatic CYP P450 (2C19, 3A4/5, 2B6, 2C9) | Hepatic CYP34/5 | CYP P450 (3A4, 2J2) |
| Conversion to active metabolite | ∼100% | 15% | 85% | 90–100% | ∼ 20% to M20 |
| Binding property | Irreversible Ser529 of COX-1 | Irreversible Free thiol of Cys97 | Irreversible Free thiol of Cys97 | Reversible At site distinct from ADP-binding site | Reversible |
| Half-life | Salicylate excretion dependent on urine pH | ∼ 20 min post-75 mg (active metabolite) | ∼ 30 min post- 10 mg ∼ 7.4 h post-60 mg (active metabolite) | ∼7 h | 3–5 d |
| Time to steady state inhibition | 30 min post-100 mg bolus | 8 h post- 600 mg | 1–2 h post-60 mg | 2 h post-180 mg | 7 d post-2.08 mg |
| Pharmacodynamic Off set | 7–10 d | 5–7 d | up to 9 d | 5–7 d | >4 wk |
| Level of inhibition at steady state | >95% inhibition of TxA2 | ∼40–50% wide response variability | ∼65–80% | ∼65–80% | ≥80% |
| Off target effects | Multiple | None significant | None significant | Inhibition of adenosine reuptake | None significant |