The purpose of this issue of my blog is to analyze and discuss a recent article in the Journal of the American Medical Association issue of the week of May 20, 2009: "Association Between Tamulosin (i.e. Flomax) and Serious Ophthalmic Adverse Events in Older Men Following Cataract Surgery", Bell, C.M. et. al., JAMA, vol. 301, pp. 1991-1996, 2009.
A very brief "summary" would suggest that all men with BPH who are on Flomax, 0.4 mg., 1 or 2 at bedtime, should ask their internist or urologist to switch them to Uroxatral, 10 mg. (and no, I do not receive any money from drug companies).
A short discussion of human anatomy and physiology is in order. The kidneys make urine continuously, which collects in the renal calyces and drains by peristaltic action through the bilateral ureters into the bladder. At the bottom of the bladder, the urine exits through the ureter. The ureter first passes through the prostate gland, which sits directly under the bladder, and then through the center of the penis to the outside world.
A few parts of the human body continue to grow throughout adult life. Some of these are the prostate gland, the tip of your nose (which is why witches are always pictures as having long, curved noses), your ears, ...Now the prostate has 3 lobes, the right, left and middle. Your physician examines and estimates the size of your prostate (and looks for prostate cancer) when he/she does a rectal exam. However, the middle lobe, which is almost impossible to feel or estimate, is the part that concerns us here. The urethra passes through the middle lobe, where it contains smooth muscle in its walls, which helps to maintain the urinary sphincter so that you don't dribble urine, or accidentally urinate when you are ejaculating sperm and seminal fluid.
As the prostate grows, the prostatic urethra slowly gets compressed, so that its diameter is functionally reduced. It then takes you longer to start urinating, and longer to complete urinating. It also makes it difficult to empty your bladder completely. Since you make approximately the same amount of urine each day, then if you can't empty your bladder as completely as you once did, then you have to empty it more often, in order to maintain the same 24 hour output to the outside world.
Often the earliest sign of this that is troubling to men is the awakening at night caused by the need to evacuate some urine. By the time a patient has to awaken two or three times, then quality of life generally enables them to agree to take medicine for this condition.
The lining of the smooth muscle walls of the urethra in the prostate contain alpha-receptors, as do the walls of blood vessels. Without going into overwhelming detail, stimulation of the alpha receptors (e.g. by nor-epinephrine, a hormone produced by the adrenal gland) causes the urethra to contract further. An alpha-blocker enables the prostatic urethra to relax. This permits a man to empty his bladder more completely, and therefore, usually, to sleep through the night or awaken no more than once. (I am not discussing the use of Proscar or Avodart here.)
Unfortunately, alpha (actually alpha-1) receptors are also present in the dilator muscle of the iris, as well as its arteriolar walls. Because of this, then alpha blocking can cause the "floppy iris syndrome" during and after cataract surgery. The conclusion of the article was that "exposure to tamulosin within 14 days of cataract surgery was significantly associated with serious post-operative ophthalmic events. There were no significant associations with exposure to other alpha-blocker medications used to treat BPH".
You will have to read the article yourself or discuss it with your ophthalmologist to help evaluate how this article applies to you. I have already switched all my Flomax patients to Uroxatral, and explained why. I have had some battles with HMO's over this, since Flomax is available in a generic form while Uroxatral is not.