THERAPEUTICS

Brands

• Aggrenox

Generic?

• Yes

Class

• Antiplatelet agent

Commonly Prescribed for

(FDA approved in bold)

• To reduce risk of recurrent transient ischemic attack (TIA) or ischemic stroke (IS) due to thrombosis

• Adjunctive prophylaxis of thromboembolism after cardiac valve replacement (adjunctive with warfarin: use dipyridamole only)

How the Drug Works

• Aspirin: by acetylating cyclo-oxygenase-1 (COX-1), aspirin irreversibly inhibits thromboxane synthetase, reducing synthesis of thromboxane A2, a prostaglandin derivative that is a potent vasoconstrictor and inducer of platelet aggregation

• Dipyridamole: inhibits (1) thromboxane synthetase, (2) the cellular reuptake of adenosine into platelets, endothelial cells, and erythrocytes, and adenosine deaminase, which both increase extracellular adenosine levels leading to stimulation of platelet adenylate cyclase and inhibition of platelet aggregation, and (3) phosphodiesterase, augmenting the effect of endothelium-derived relaxing factor (nitric oxide)

How Long Until It Works

• 1–2 hours. Inhibits platelet aggregation for the life of the platelet (7–10 days)

If It Works

• Continue to use

If It Doesn't Work

• Only reduces risk of myocardial infarction (MI) or stroke. Warfarin is superior for cardiogenic stroke. Control all stroke risk factors such as smoking, hyperlipidemia, and hypertension. For acute events, admit patients for treatment and diagnostic testing

Best Augmenting Combos for Partial Response or Treatment-Resistance

• Combinations with other antiplatelet agents are not recommended

Tests

• None required

ADVERSE EFFECTS (AEs)

How the Drug Causes AEs

• Antiplatelet effects increase bleeding risk. Effects on nitric oxide may produce headache

Notable AEs

• Headache, abdominal pain, dyspepsia, nausea/vomiting, diarrhea, arthralgia, hypotension, epistaxis

Life-Threatening or Dangerous AEs

• GI, intracranial, or intraocular bleeding. Rare hepatic failure

Weight Gain

• Unusual

Sedation

• Unusual

What to Do About AEs

• For significant GI or intracranial bleeding, stop drug. For intolerable headaches, switch to 1 capsule at bedtime and low-dose aspirin in the morning for 1 week (headaches usually resolve in 1 week or less)