Hi Allen:
A very interesting question. I'm not aware of any studies that look at the use of DDAVP (desmopressin acetate) in diving. DDAVP is a synthetic analog of the hormone arginine vasopressin- an anti-diuretic hormone (ADH). Your body can sense the volume and concentration of fluids in the bloodstream and make adjustments to keep that volume and concentration normal. ADH is secreted by the pituitary gland and works directly on the kidneys to keep the volume of fluids in body higher and the concentration lower by retaining water.
As already discussed in the Women Only forum thread that you mentioned (
http://www.scubaboard.com/showthread.php?threadid=10 ) diving causes a shift of body fluids into the circulation. This shift increases the volume of fluid in the bloodstream. Your body senses this increase in volume and decreases the production of ADH so you will excrete this "excess" volume (pee!). Taking DDAVP would work directly to counteract this reflex.
As I mentioned above, I'm not aware of any studies looking at scuba divers using DDAVP. Would affecting the results of these fluid shifts be good or bad? Dunno. DDAVP can also have side effects. It can be used as either a shot, a nasal spray, or a pill. When used as a pill DDAVP can cause headaches. When used as a nasal spray DDAVP can cause headaches, nausea, rhinitis (inflammation of the nose), facial flushing, asthenia (weakness), chills, conjunctivitis (inflammation of the eye), cough, dizziness, eye edema, GI disorder, lacrimation (tears), nosebleed, nostril pain, sore throat, and maybe even increase the incidence of upper respiratory tract infections. It can also cause swelling of the mucus membranes of the nose and sinuses that might interfere with equalizing. Since DDAVP causes your kidneys to hold on to water it is possible to develop "over-hydration" and water intoxication when on the drug. It is sometimes recommended that fluid intake be restricted when taking DDAVP, which runs counter to the recreational diving mantra of "drink more fluids". Divers are physically active and breathing dry air so they tend to want to drink lots of fluids anyway. DDAVP could make it difficult for the diver to know how much fluid is enough and how much is too much.
An interesting question, but until more is known about DDAVP and diving, I would not recommend its use as a means of reducing urine volume. Better to use a "nappie" or dive wet, IMO.
Hope this helps,
Bill
