Do COX-2 inhibitors affect platelets?
Do COX-2 inhibitors affect platelets?
At therapeutic doses, COX-2 selective inhibitors have little effect on the COX-1 enzyme, so they do not inhibit platelet aggregation.
Do COX-1 inhibitors affect platelets?
Only the COX inhibitors that inhibit COX-1 can inhibit synthesis of TxA2. Selective COX-2 inhibitors do not inhibit Thromboxane A2 and have no effect on platelets.
Which COX pathway regulates platelet aggregation?
In platelets, COX-1 is essential for the synthesis of TxA2, which stimulates platelet aggregation and vasoconstriction, and thus exerts hemostatic/thrombogenic effect. Pharmacological inhibition of TxA2 synthesis leads to the inhibition of platelet aggregation.
Do COX-2 inhibitors cause vasodilation?
Selective COX-2 inhibition does not affect either prostacyclin or nitric oxide mediated vasodilation in the canine coronary circulation.
Do platelets have COX-2?
We have detected a significant amount of COX2 in platelets, both at mRNA and protein levels. We found that COX1/COX2 mRNA and protein ratios in platelets were 3–7:1, and 17:1, respectively. Expression level of COX2 in platelets was less than COX1, but comparable to the expression of COX2 in malignant epithelial cells.
What is a COX-1 and 2 inhibitor?
There are two types of COX enzymes, COX-1 and COX-2. Both enzymes produce prostaglandins that promote inflammation, pain, and fever; however, only COX-1 produces prostaglandins that activate platelets and protect the stomach and intestinal lining. NSAIDs block the COX enzymes and reduce production of prostaglandins.
Is naproxen a COX-1 or COX-2 inhibitor?
Naproxen is a non-steroidal, antiinflammatory agent. It is a non-selective COX-1 and COX-2 inhibitor Mitchell et al (1993). Structurally, naproxen is a propionic acid-derived, non-steroidal, anti-inflammatory drug with a chiral center.
How does COX-2 selective inhibitors affect platelet aggregation?
At therapeutic doses, COX-2 selective inhibitors have little effect on the COX-1 enzyme, so they do not inhibit platelet aggregation. As COX-2 selective inhibitors do not inhibit thromboxane A 2 synthesis they could be predicted to increase the risk of thrombosis.
How are Cox 2 inhibitors used to treat bleeding?
Of note, the COX-2 inhibitors do not affect platelet function. This is an advantage if bleeding is a potential complication. However, many physicians accustomed to using a nonsteroidal for its anti-inflammatory and anti-platelet actions need to remember to add a specific anti-platelet agent if needed.
Are there any side effects of COX 2 inhibitors?
Use of aspirin in the class study has shown that the benefits of COX-2 inhibitors may be reduced by aspirin use. The VIGOR study has raised the possibility that some NSAIDs, particularly naproxen, may protect against vascular disease compared to COX-2 inhibitors (or placebo).
How are COX-2 selective inhibitors related to thrombosis?
As COX-2 selective inhibitors do not inhibit thromboxane A2 synthesis they could be predicted to increase the risk of thrombosis. Thromboxane A2 is not only a stimulus for platelet aggregation but also a powerful vasoconstrictor (Fig. 1). Its effects are opposed by prostacyclin, a vasodilator prostaglandin and inhibitor of platelet aggregation.
