Which of the following drugs is known to be a risk factor for deep venous thrombosis (DVT)?

Oral contraceptives are associated with an increased risk of deep venous thrombosis (DVT) primarily due to their content of estrogen. Estrogen can influence the coagulation cascade by increasing levels of clotting factors and reducing levels of natural anticoagulants, leading to a hypercoagulable state. This is particularly concerning in women who may have additional risk factors for thrombosis, such as obesity, smoking, or a personal or family history of clotting disorders.

This connection has been well-established in medical literature, highlighting that women using oral contraceptives are advised to be aware of DVT symptoms and to consult healthcare providers regarding their individual risks, especially if they have other predisposing factors.

In contrast, while aspirin is an antiplatelet medication that may help prevent clot formation, it does not significantly raise the risk of DVT. tPA, or tissue plasminogen activator, is used in the treatment of acute thrombotic events and is not a risk factor for DVT development. Plavix (clopidogrel) is also an antiplatelet agent and similarly does not contribute to an increased risk of DVT.