There Is An Approximate Two Times Increased Risk Of NAION According To Recent Medical Study, Which Is Consistent With Some Earlier Medical Research

 

(Posted by Tom Lamb at DrugInjuryWatch.com)

 

As reported previously, the erectile dysfunction (ED) drugs Cialis (tadalafil), Levitra (vardenafil hydrochloride), and Viagra (sildenafil citrate) have been associated with a type of sudden vision loss called Nonarteritic Anterior Ischemic Optic Neuropathy (NAION).

In July 2005 the FDA ordered warnings be put on the package insert labels of these ED drugs, or impotence drugs, to the effect that some users of Cialis, Levitra, and Viagra have developed NAION, a form of blindness. At the same time, however, the FDA stated that it is impossible at present to know if NAION is a side effect of these ED drugs, or an unrelated medical condition.

In June 2006 Health Canada issued a Public Communication alerting Canadians that the drug companies Eli Lilly (Cialis), Bayer (Levitra), and Pfizer (Viagra) were in the process of sending a so-called “Dear Doctor” letter to inform healthcare providers in Canada about changes to the respective package insert, or label, for these drugs regarding this vision loss, or NAION, side effect.

Now, 11 years later, in August 2017, there is some additional information about the increased risk of developing the eye or vision side effect NAION which is included in a recent label change for Viagra, Cialis, and Levitra.

 

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From a comparison of the relevant parts of the two most recent drug labels for Levitra, below, you can see what was added by means of this August 2017 label change concerning NAION as a possible adverse drug event or adverse reaction (in the second and third paragraphs of the current drug label).

 

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FULL PRESCRIBING INFORMATION document for Levitra (Revision Date: 9/2015)

5.4 Effects on the Eye

Physicians should advise patients to stop use of all phosphodiesterase type 5 (PDE5) inhibitors, including LEVITRA, and seek medical attention in the event of sudden loss of vision in one or both eyes. Such an event may be a sign of nonarteritic anterior ischemic optic neuropathy (NAION), a rare condition and a cause of decreased vision, including permanent loss of vision, that has been reported rarely postmarketing in temporal association with the use of all PDE5 inhibitors. Based on published literature, the annual incidence of NAION is 2.5–11.8 cases per 100,000 in males aged ≥50. An observational study evaluated whether recent use of PDE5 inhibitors, as a class, was associated with acute onset of NAION. The results suggest an approximate 2 fold increase in the risk of NAION within 5 half-lives of PDE5 inhibitor use. From this information, it is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors [see Adverse Reactions (6.2)]. 

 

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FULL PRESCRIBING INFORMATION document for Levitra (Revision Date: 8/2017)

 

5.4 Effects on the Eye

Physicians should advise patients to stop use of all phosphodiesterase type 5 (PDE5) inhibitors, including LEVITRA, and seek medical attention in the event of sudden loss of vision in one or both eyes. Such an event may be a sign of nonarteritic anterior ischemic optic neuropathy (NAION), a rare condition and a cause of decreased vision, including permanent loss of vision, that has been reported rarely postmarketing in temporal association with the use of all PDE5 inhibitors. Based on published literature, the annual incidence of NAION is 2.5–11.8 cases per 100,000 in males aged ≥50.

An observational case-crossover study evaluated the risk of NAION when PDE5 inhibitor use, as a class, occurred immediately before NAION onset (within 5 half-lives), compared to PDE5 inhibitor use in a prior time period. The results suggest an approximate 2-fold increase in the risk of NAION, with a risk estimate of 2.15 (95% CI 1.06, 4.34). A similar study reported a consistent result, with a risk estimate of 2.27 (95% CI 0.99, 5.20). Other risk factors for NAION, such as the presence of “crowded” optic disc, may have contributed to the occurrence of NAION in these studies.

Neither the rare postmarketing reports, nor the association of PDE5 inhibitor use and NAION in the observational studies, substantiate a causal relationship between PDE5 inhibitor use and NAION [see Adverse Reactions (6.2)].

 

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We will continue to monitor the safety profile of Viagra, Cialis, and Levitra as regard the vision-loss condition NAION as well as other possible ED drugs side effects.

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