On March 30, 2010, the U.S. Food and Drug Administration (FDA) posted a notice from Natural Wellness warning consumers not to purchase or consume the product known as MasXtreme, Lot# 911035. This product which is being marketed as a dietary supplement contains undeclared amounts of Aildenafil, as well as the drug Phentolamine which is an alpha-adrenergic blocker. Aildenafil is close in structure to Sildenafil and is expected to possess a similar pharmacological and adverse event profile. Sildenafil is the active pharmaceutical ingredient in an FDA-approved drug that is used to treat erectile dysfunction (ED). This may pose a threat to consumers because Aildenafil may interact with nitrates found in some prescription drugs (such as nitroglycerin) and may lower blood pressure to dangerous levels. Consumers with diabetes, high blood pressure, high cholesterol, or heart disease often take nitrates. Common side effects of Phentolamine include arrhythmia (abnormal heart rhythm) and tachycardia (rapid heart beat).