Cialis - recent DAN article

[DiverAmy]

Dan recently reported this:

Cialis™/Viagra™ and the Risk of Oxygen Toxicity

"Reports to DAN suggested that oxygen toxicity risk might be increased by these drugs. This was found to be true in a rat model."

Does anyone have any information regarding this? Should men not take Cialis before diving NITROX? If so, how long do they have to wait to dive after taking Cialis? I believe the article in Alert Diver (page 87. Winter 2013) suggested that men on Cialis change their partial pressure setting (or avoid high partial pressure). What should a man with Cialis in his system consider his upper limit on partial pressure? Duke University was doing the research, as I recall. Any input would be appreciated.

 

[nimoh]

not to mention there is an additional snagging hazard...sorry, couldn't resist.

 

[Jim Lapenta]

Good thing rats don't dive. Except in sewers.

 

[Kilili]

When I go to the DAN page, there's no content listed under the article title.

Check this, which has a contrary perspective.
http://www.scuba-doc.com/tenfootstop/?p=221

Also some info here:
http://www.scubaboard.com/forums/ask-dr-decompression/344087-cialis.html

 

[616fun]

Note that this is a current study that has netted no scientific result to date. My general thought is someone who's been diagnosed with ED has several other factors that could be considered a contraindication for diving. Diabetes, high blood pressure, depression, cardiovascular illness are to name a few.

Let not jump to conclusions until the data is in, but I'd say if you are experiencing ED there are underlying causes that would lend a diver to conduct conservative dives.

 

[boulderjohn]

I absolutely would not get too excited about it (ahem!) for recreational diving. I have come to the conclusion that if you are within normal recreational diving NDLs and even pushing the established O2 limits, it is pretty darn hard to have a toxing event.

There is a DAN paper published long ago on the supposed possibility that Sudafed will increase the likelihood of O2 toxicity. They finally conclude that it is best not to use Sudafed in high O2 situations, but about 80% of the paper is devoted to telling you why they have only the barest minimum of data on which to make that recommendation and why you should not pay any attention to it. I suspect this is a similar situation.

 

[DiverAmy]

Thanks for the input, thus far, both serious and otherwise.

 

[DocVikingo]

Hi AmyLoraR,

The material to which you are referring is mentioned within the text of a paragraph entitled "Oxygen Toxicity and Erectile Dysfunction Drugs" by Dr. Petar Denoble (Senior Director of DAN Research). It appears on page 87 of the Winter 2013 issue of Alert Diver. The conclusions are at least in part based on work done by Dr. Ivan Demchenko and colleagues at the Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center. Findings of note to your inquiry include a reduction in seizure threshold in rats given PDE-5 inhibitors (such as Viagra (sildenafil) & Cialis (tadalafil)) under conditions of hyperbaric 02. You may read the abstract of the study here -->

Demchenko, IT; Ruehle, A; Allen, BW; Vann, RD; Piantadosi, CA. EFFECTS OF PHOSPHODIESTERASE-5 INHIBITORS ON CEREBRAL BLOOD FLOW AND SEIZURES IN RATS EXPOSED TO HBO2. (Abstract) Undersea Hyperb Med. 2008 July-Aug;35(4) RRR ID: 7893 ([abstract] EFFECTS OF PHOSPHODIESTERASE-5 INHIBITORS ON CEREBRAL BLOOD FLOW AND SEIZURES IN RATS EXPOSED TO HBO2.)

Another related & informative work can be found at --> Demchenko, IT; Piantadosi, CA. Nitric oxide amplifies the excitatory to inhibitory neurotransmitter imbalance accelerating oxygen seizures. Undersea Hyperb Med. 2006 May-Jun;33(3):169-74. RRR ID: 5056 (http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/5056/16869530.pdf?sequence=1)

I'll only mention in passing that there can be multiple issues in generalizing findings from studies done on rodents to humans. You'll also want to note that the rats in the experiment were compressed to 6 ATA 02.

As mentioned in the Alert Diver paragraph, of importance is the effective duration of the chosen medication. In this regard, studies show a plasma elimination half-life for Viagra (sildenafil) of about 3–4 hours. As might reasonably be inferred from the ads for Cialis (tadalafil), it's half-life is very much longer, on the order of 15-18 hours. Of course for those on once-daily chronic administration, plasma levels don't decrease for the duration of the regimen. Clearly these facts can have implications for the diver and should be discussed with an appropriately knowledgeable physician.

There simply isn't enough known about this topic to allow for accurate & detailed answers to questions such as, "What should a man with Cialis in his system consider his upper limit on partial pressure?" What can comfortably be said is that based on theory and very limited research in rats, a diver taking erectile dysfunction medication of the PDE-5 inhibitor class might be prudent to control plasma levels during dives and to dive profiles designed to minimize pp02 such as diving air rather than EAN and keeping depths relatively shallow.

Regards,

DocVikingo

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual and should not be construed as such.

---------- Post added March 12th, 2013 at 06:18 AM ----------

Check this, which has a contrary perspective. Diving and ED Medications? « Scubadoc?s Ten Foot Stop

Contrary perspective? I'm a little confused here, Kilili.

The OP inquired regarding Cialis and possibly increased oxygen toxicity risk.

The article by ScubaDoc that you cite primarily theorizes about Cialis and possibly decreased chances of getting bubble related diving illnesses. [And the research abstract provided by ScubaDoc addresses nitroglycerine and reduced bubble formation after diving.] There is no mention whatsoever of ox-tox issues that I can locate on that page.

Isn't this apples & oranges or have I missed something (which certainly is possible)?

Thanks,

DocVikingo

---------- Post added March 12th, 2013 at 07:02 AM ----------

I absolutely would not get too excited about it (ahem!) for recreational diving. I have come to the conclusion that if you are within normal recreational diving NDLs and even pushing the established O2 limits, it is pretty darn hard to have a toxing event.

Amen brother John.

Cheers,

DocV

 

[DiverAmy]

Thanks for the response DocV and as a lawyer, I appreciate your disclaimer. Your response was EXACTLY the type of input I was seeking.

 

[drbill]

Gulp... so now I have to choose between having a love life and diving. Sorry, ladies... you all know what comes first in my life. Tee hee. At least I don't dive geezer gas.