From the Research
Long-acting nitrates should not be used concurrently with papaverine and phentolamine injections due to the risk of severe hypotension. These medications work through different mechanisms but both ultimately cause vasodilation. Long-acting nitrates (like isosorbide mononitrate or isosorbide dinitrate) release nitric oxide which relaxes vascular smooth muscle, while the combination of papaverine (a phosphodiesterase inhibitor) and phentolamine (an alpha-adrenergic blocker) also produces vasodilation through different pathways. When used together, these medications can cause an additive or synergistic hypotensive effect that may result in dangerous drops in blood pressure, potentially leading to dizziness, fainting, cardiovascular collapse, or cerebral hypoperfusion. If a patient is using papaverine-phentolamine injections (commonly used for erectile dysfunction), they should inform their healthcare provider about all medications they are taking, especially nitrates. Patients with cardiovascular conditions requiring nitrate therapy should discuss alternative treatments for erectile dysfunction with their healthcare provider. The contraindication is similar to that seen with PDE5 inhibitors like sildenafil and nitrates, as noted in a study published in the Journal of cardiovascular pharmacology and therapeutics 1. Key points to consider include:
- The risk of severe hypotension with concurrent use of long-acting nitrates and papaverine-phentolamine injections
- The importance of informing healthcare providers about all medications being taken, especially nitrates
- The need to discuss alternative treatments for erectile dysfunction in patients with cardiovascular conditions requiring nitrate therapy
- The similarity in contraindication to that seen with PDE5 inhibitors like sildenafil and nitrates, as supported by a study published in Expert opinion on drug safety 2. It is crucial to prioritize the patient's safety and well-being by avoiding the concurrent use of these medications, as the potential risks outweigh any potential benefits, and alternative treatments should be explored.