What is the difference between tadalafil (Cialis) and nitroglycerin?

From the Guidelines

Tadalafil (Cialis) and nitroglycerin are two distinct medications with different mechanisms of action and uses. Tadalafil is a phosphodiesterase type 5 inhibitor used to treat erectile dysfunction, while nitroglycerin is a vasodilator used to treat angina and other heart conditions.

Key Differences

• Mechanism of action: Tadalafil works by increasing blood flow to the penis, while nitroglycerin works by dilating blood vessels to reduce myocardial oxygen demand and improve blood flow to the heart.
• Indications: Tadalafil is used to treat erectile dysfunction, while nitroglycerin is used to treat angina, heart failure, and other heart conditions.
• Contraindications: The use of nitrates, including nitroglycerin, is a contraindication for oral phosphodiesterase type 5 inhibitor therapy, including tadalafil, due to the risk of severe hypotension 1.
• Half-life: Tadalafil has a half-life of 17.5 hours, while nitroglycerin has a shorter half-life and its effects last for a shorter duration.

Important Considerations

• Concomitant use: Patients on tadalafil should avoid taking nitroglycerin for at least 48 hours, while patients on nitroglycerin should avoid taking tadalafil due to the risk of severe hypotension 1.
• Alternative options: In patients on long-acting nitrate therapy who want to use a phosphodiesterase type 5 inhibitor, the decision should be guided by the need for continued nitrate therapy versus other alternative options available to the treating clinician 1.
• Dosing and administration: Nitroglycerin can be administered sublingually, intravenously, or transdermally, while tadalafil is typically taken orally 1.

From the FDA Drug Label

Do not take nitroglycerin sublingual tablets with drugs for erectile dysfunction, like VIAGRA® (sildenafil citrate), CIALIS® (tadalafil), or LEVITRA® (vardenafil hydrochloride), as this may lead to extreme lowering of your blood pressure The main difference between tadalafil (Cialis) and nitroglycerin is their:

• Mechanism of action: Tadalafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), while nitroglycerin is a vasodilating agent.
• Indication: Tadalafil is used to treat erectile dysfunction, while nitroglycerin is used to treat angina.
• Contraindication: Nitroglycerin should not be taken with tadalafil, as it may lead to extreme lowering of blood pressure 2.

From the Research

Difference between Tadalafil and Nitroglycerin

• Tadalafil, also known as Cialis, is a phosphodiesterase 5 (PDE5) inhibitor used to treat erectile dysfunction (ED) 3, 4, 5.
• Nitroglycerin, on the other hand, is a nitrate used to treat angina and other heart conditions by relaxing blood vessels and improving blood flow 3, 6.
• The main difference between tadalafil and nitroglycerin is their mechanism of action: tadalafil works by inhibiting PDE5, increasing the levels of cyclic guanosine monophosphate (cGMP) in cavernous smooth muscle cells, leading to smooth muscle relaxation and penile erection 7, while nitroglycerin works by releasing nitric oxide, which stimulates the production of cGMP, causing vasodilation and relaxation of blood vessels 6.
• Another key difference is the duration of action: tadalafil has a longer duration of action, up to 36 hours, compared to nitroglycerin, which has a shorter duration of action 7.
• Additionally, tadalafil and nitroglycerin should not be used together, as their combined use can lead to significant hypotensive effects, including a synergistic decrease in blood pressure 3, 6.

Interaction between Tadalafil and Nitroglycerin

• The interaction between tadalafil and nitroglycerin is significant, as both drugs can cause a decrease in blood pressure, and their combined use can lead to hypotension 3, 6.
• Studies have shown that the interaction between tadalafil and nitroglycerin can last for up to 48 hours after tadalafil administration, due to the longer elimination half-life of tadalafil 3.
• It is recommended that patients taking nitrates, including nitroglycerin, should not use tadalafil or other PDE5 inhibitors, as the risk of hypotension and other adverse effects is increased 3, 6.

Clinical Implications

• The difference between tadalafil and nitroglycerin has important clinical implications, as patients with ED who are also taking nitrates for angina or other heart conditions should not use tadalafil or other PDE5 inhibitors 3, 6.
• Healthcare providers should carefully evaluate the medical history and current medications of patients before prescribing tadalafil or other PDE5 inhibitors, to minimize the risk of adverse interactions with nitrates or other medications 3, 6.