Is tadalafil (phosphodiesterase type 5 inhibitor) safe in a patient with essential thrombocytosis (ET)?

Tadalafil Safety in Essential Thrombocythemia

Tadalafil is generally safe for use in patients with essential thrombocythemia (ET), but should not be used concomitantly with nitrate medications due to the risk of severe hypotension. 1

Safety Considerations for PDE5 Inhibitors in ET

• Phosphodiesterase type 5 (PDE5) inhibitors like tadalafil have shown no specific concerns regarding cardiovascular events in patients with cardiovascular disease, and by extension, in patients with ET 1
• Recent analyses of placebo-controlled and postmarketing surveillance data have demonstrated no new concerns regarding cardiovascular events with PDE5 inhibitors 1
• The primary contraindication for tadalafil is concomitant use with nitrate medications, which can cause severe hypotension 1

Specific Timing Considerations

• Tadalafil has a longer half-life (17.5 hours) compared to other PDE5 inhibitors 1
• Patients taking tadalafil should avoid nitroglycerine for at least 48 hours due to this extended half-life 1
• For patients on long-term nitrate therapy who want to use tadalafil, the decision should be guided by weighing the need for continued nitrate therapy against other available treatment options 1

Thrombotic and Bleeding Risk in ET

• Essential thrombocythemia is characterized by an increased risk of both thrombotic and bleeding complications 2
• The primary concern in ET patients is managing the risk of thrombosis and hemorrhage, which are the main clinical manifestations of the disease 3
• Recent research (2024) indicates that extreme thrombocytosis (platelet count ≥1000 × 10^9/L) in ET does not significantly increase bleeding risk compared to non-extreme thrombocytosis 4
• This suggests that the presence of ET alone should not be considered a contraindication to tadalafil therapy 4

Management Approach for ET Patients Requiring Tadalafil

• Assess the patient's cardiovascular risk status before prescribing tadalafil 1
• For patients with indeterminate cardiovascular risk (including those with non-cardiac sequelae of atherosclerotic disease), consider additional vascular disease assessment 1
• Ensure the patient is not taking nitrate medications before prescribing tadalafil 1
• Consider the patient's ET-specific risk factors, including age >60 years and history of thrombosis, which define high-risk ET 2
• For high-risk ET patients, ensure appropriate cytoreductive therapy (typically hydroxyurea) is being used to control platelet counts 2

Special Considerations

• If the patient has extreme thrombocytosis (≥1000 × 10^9/L), this alone should not preclude tadalafil use, as recent evidence suggests no significant difference in bleeding risk compared to non-extreme thrombocytosis 4
• For patients with ET who are also on antiplatelet therapy (such as aspirin), there is no specific contraindication to using tadalafil, but monitor for any unusual bleeding 3
• In patients with both ET and cardiovascular disease, management of ED should always be considered secondary to maintaining cardiovascular function 1

By following these guidelines and considering the specific characteristics of the patient's ET and cardiovascular status, tadalafil can be safely prescribed to patients with essential thrombocythemia who do not have contraindications such as concomitant nitrate use.