Advances in Erectile Dysfunction

Differentiating the oral medications for ED

Illustration of capsules and pills on green background
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In 1998, sildenafil, better known by its trade name, Viagra, hit the market.  Viagra revolutionized the treatment of erectile dysfunction; it even invented the term.  Impotence was the diagnostic word for ED and still the medical term for inability to achieve erections.  But that was too harsh and the marketing term, Erectile Dysfunction, was born.  Prior to Viagra, 90% of ED was diagnosed as psychological and required sex therapy.

Post-Viagra, the numbers have switched to only about 10% of ED being attributed to psychological causes.  Since the introduction of Viagra, there have been a number of pills to hit the market including vardenafil (Levitra and Staxyn), tadalafil (Cialis) and most recently avanafil (Stendra).

What's the difference?  Let's talk a little science first to give some background to the discussion.  The class of oral medications for ED is referred to as phosphodiesterase type-5 inhibitors or, if you're looking for less of a mouthful, PDE-5i.  PDE-5i's block the breakdown of nitric oxide, the erection hormone.  Nitric oxide (NO) is a potent vasodilator, meaning it relaxes blood flow to allow more blood into a space.   The more NO, the more flow.  That's a good thing in the penis - more blood flow in means better erections, better trapping of blood in the penis and ultimately better intercourse.  That could be not such a good thing in other organs, as we'll find out.

So why the type 5 business? Because there are around 11 isoforms (similar enzymes) of phosphodiesterase in the body. NO is important in the heart, the eye, the prostate, the skeletal muscle, the GI tract and multiple other systems.  Because the isoforms are so close on a molecular level, there is crosstalk between the enzyme types.

  The ED drugs are targeted toward the PDE 5 isoform which is the pro-erection enzyme in the penis; but all of these drugs have different affinities for the other isoforms.  This affinity explains the side effect profile.  Common side effects of Viagra, Cialis and vardenafil are headaches, nasal congestion, visual changes, upset stomach, muscle aches, and back pain.  The newest drug on the market, Stendra, has a higher affinity for the pro-erection PDE-5 and a lower affinity for the side effect enzymes.  Although head to head studies between the different drugs are lacking, it appears that Stendra has a lower side effect profile.

When a man and his doctor choose which PDE-5i drug to take, they need to also determine how much booze and food the guy drinks and eats before his amorous tendencies kick in.  Viagra needs to be taken on a relatively empty stomach without alcohol.  The others don't have those restrictions.  Cialis, in about 60% of men, has a very long half-life-up to 36 hours.  This makes it pretty attractive for a guy who thinks he'll get lucky a few times in a 36 hour time frame.

  He's not so lucky if he has side effects like headaches and GI upset that last that long, however.

Stendra, the new kid on the block, has some compelling differentiators.  It has a very short onset of action. In fact, the FDA just recognized Stendra as the first and only FDA approved ED medication indicated to be taken as early as around 15 minutes prior to intercourse.  As the other drugs in class have around a 1 hour lead time, 15 minutes can greatly enhance the spontaneity of intercourse.  Great for the non-planners who never know when they might get that opportunity.  Stendra also has a relatively short half-life and, as mentioned earlier, potentially lower side effect profile.  So, if a guy does get headaches with this class of medication, he may find a shorter duration of symptoms on Stendra.

The bottom line here is if you or someone you love (or want to love) has ED, there are some great treatment options available.  Erectile dysfunction is a medical problem that needs evaluation by a medical professional.  With the new advances in medical therapy, now's a great time to seek treatment.  Another word of caution: be careful with online pharmacies promising delivery of generic ED drugs.  To date, there are no FDA approved generic drugs for ED.  If you get a generic drug from an online pharmacy you are getting, at best, a counterfeit drug that may work.  At worst, you are getting garbage that may even harm you.  Love is blind but don't go blind searching for it!

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