Alprostadil (Caverject, Edex) and sildenafil (Viagra) are both medications used to treat erectile dysfunction (ED). However, they belong to different medication classes and have distinct differences in their use and effects. Alprostadil is a prostaglandin analog administered as an intracavernous injection, while sildenafil is a phosphodiesterase-5 (PDE-5) inhibitor taken orally. Alprostadil works by relaxing muscles and opening blood vessels in the penis, whereas sildenafil blocks PDE-5 to help maintain an erection. Alprostadil is typically injected into the base of the penis before sexual activity, with effects lasting up to an hour, while sildenafil is taken by mouth about an hour before sex and can last up to 8 hours. Alprostadil is available only by prescription and does not have a generic version, whereas sildenafil is available as a lower-cost generic. Common side effects of alprostadil include penile pain and bleeding at the injection site, while sildenafil may cause headaches, flushing, and vision changes. Additionally, sildenafil has significant drug interactions, especially with nitrates, which can lead to dangerously low blood pressure.
