By Edward D. Thalmann, M.D., Captain, Medical Corps, U.S. Navy (Retired), DAN Associate Medical Director
Note: In the September/October 2003 issue of Alert Diver, the Medical Line column discussed the use of Transderm Scop in "Motion Sickness: A 'hurl' by any other name is still as unhappy," by Dan Kinkade, DAN Medical Information Specialist (link to it here). Here's an expanded look at this drug, which has been used by many divers with great success. As with all drugs, however, use under the direction of your physician.
As a diving medical officer at the Navy Experimental Diving Unit (NEDU) in Panama City, Fla., from 1977-1985, I had many opportunities to do open-sea diving off the Gulf Coast. Unfortunately, I am one of those individuals who gets seasick while taking a bath, a definite disadvantage when diving with the pros.
When I first arrived, Bill Spaur, the senior medical officer at NEDU, recommended promethazine (Phenergan®) and ephedrine as the best anti-motion sickness medication at the time. The recommendation was based on a published study by the Air Force.
Initially, this was my treatment of choice, but it failed to work in rough seas, and, after a morning's diving, I would find myself sleeping the rest of the day. When Transderm Scop came on the market, I tried it, and my problems disappeared. For once, I could function normally, without the slightest hint of motion sickness, even in the roughest seas. Soon the word spread, and requests for this prescription drug were pouring in from the NEDU divers.
At NEDU, we established a policy that before issuing the drug, the diver had to place the patch and wear it 24 hours on dry land and then be interviewed by one of the diving medical officers. This would ensure that no one experienced undesirable side effects before diving. The patch had to be placed one hour before leaving shore, but once in place, it could be worn even while diving. The only problem was that since it was placed behind an ear, it would sometimes fall off - unnoticed - until that queasy feeling set in.
Because this drug was so effective, we decided that it might be worthwhile to recommend it for all Navy divers. First, we thought we had to verify that there were no effects, which worsen at depth. With this in mind, we performed a study, in which divers on a 60-foot / 18-meter air saturation dive that lasted five days, were each given a patch containing either the scopolamine or a placebo. It was a blinded study; divers did not know which patch they received. Divers performed psychomotor studies several times during the dive; they were also asked to write down anything perceived as a side effect that occurred throughout the day.
The results? Basically, there was no difference between the two groups, so we concluded that modest hyperbaric exposures would not increase the probability of side effects or adversely affect performance within the normal scuba diving depth range. The results of the study were presented at the 1985 annual meeting of the Undersea and Hyperbaric Medical Society in Long Beach, Calif. (Abstract #52, Schwartz and Curley).
Transderm Scop is my personal choice for motion sickness prophylaxis, and you'll find it recommended in the U.S. Navy Diving Manual (paragraph 8-8, 1993 edition). However, certain people do suffer side effects that would make it inappropriate for them. A physician must prescribe it, and one should test it before diving. Wear a patch for at least 24 hours on dry land in a situation where the potential side effects will not cause harm. If no side effects occur, then try it out on a dive. To ensure it won't fall off, apply the patch to thoroughly clean and dry skin.
The Transderm Scop patch is a prescription medication that contains 1 mgm of scopalomine. When placed on the skin the patch will deliver the drug at a constant rate for three days. After that period, the patch should be removed. If you are still in an environment where motion sickness will be a problem, another patch may be placed immediately. Never wear more than one patch at a time, even if you think one is exhausted. There is a risk of too much of the medication entering the bloodstream, causing undesirable side effects.
When one dives, the patch should be placed at least an hour before boarding the boat. The area behind the ear should be scrubbed with an alcohol and dried well. Once the patch is placed, it can be left there continuously for three days, even when diving. If the patch falls off or is removed, it should be discarded. If motion sickness is still likely to be a problem, a new patch may then be placed immediately. Remember, before placing a new patch, remove the old one.
When the patch is opened, do not touch the skin side of the patch. If some of the medication gets on a finger and you touch your eye, the drug is absorbed very rapidly. Side effects may occur. It is recommended that no alcohol be consumed while wearing the patch.
Side effects include dry mouth, drowsiness and blurred vision. Less frequently, disorientation, memory disturbances, dizziness and restlessness may occur. Rare side effects include hallucinations, confusion, difficulty urinating, skin rashes and eye pain. These side effects depend on each individual; there is no way to know in advance who will be affected. Thus, before using it to prevent motion sickness, the patch should be worn on dry land. If side effects occur, the patch should be removed and not worn.
Please make two important considerations when choosing the patch: scopolamine can cause problems for individuals with glaucoma or an enlarged prostate.
If you have narrow-angle glaucoma, you should not use this product without medical advice: it may precipitate a severe episode. Because scopolamine can cause acute urinary retention, individuals with enlargement of the prostate should use only under a doctor's advice.
Remember, if the patch is worn for more than three days, withdrawal symptoms can occur. Symptoms generally do not occur until 24 hours after removal; they include dizziness, nausea, vomiting, headache and disturbances of equilibrium. These symptoms are also associated with decompression sickness. They can affect the central nervous system, and they can complicate diagnosis if the patch is removed right after making a deep dive. If you have these symptoms and you wore the patch at any time, tell the examining physician.
Originally appeared in Alert Diver, November / December 2003.