Tuesday, January 20, 2009

Pyridium (phenazopyridine)

Chances are good that this specimen will look familiar to those of you who have been treated for a urinary tract infection known as cystitis. While waiting for the antibiotics to start to work killing the unwanted bacteria invading your bladder, your doctor may have given you Pyridium, an analgesic that soothes the burning pain and spasms of the infection and turns your pee the color of orange Kool-Aid in the process.

A case report in the Mayo Clinic's journal last year(1) is a good reminder that even that which seems innocuous-- a drug taken for a day or two to jump start recovery from a bladder infection-- can have serious side effects. This little old lady with a history of recurrent urinary tract infections (a problem common both to little old and not-so-little, not-so-old ladies) complained her urine was orange and her hands were blue. No problem with the orange urine, we see that of course all the time with the initial use of Pyridium. But what was up with the alarming discoloration of her hands and her ear lobes?

The satisfying pink color of our palms derives from the oxygenated blood carried in the arteries within. Hemoglobin combined with oxygen or oxyhemoglobin imparts that familiar red hue to arterial blood. In order to grab an oxygen molecule, the iron in hemoglobin must be in its reduced or ferrous state with a free electron which can bind to a free electron hanging off the oxygen we absorb through our lungs. When iron is oxidized into its ferric state, a lack of a free electron means no oxygen-binding resulting in methemoglobin which is brown and causes a dusky discoloration to skin. In a normal healthy state, enzymes act to reduce methemoglobin back to oxyhemoglobin.

What's all this got to do with seeking a little relief from a bad bladder day? While a little relief, i.e. a day or two of Pyridium is a good thing, ongoing use of the drug--in this case ten days--is a bad thing. Pyridium and other drugs that diminish the activity of reductase enzymes can result in methemoglobin production. A little abnormal hemoglobin makes your digits blue, a lot makes you seize, fall into a coma, and die.

I've not seen a case of this in all the years I've prescribed this analgesic for UTIs. But this is a good reminder that some folks, on receiving a prescription of thirty Pyridium with the instructions to take it three times daily as needed for bladder pain will do just that, take the entire prescription rather than quitting its use when the bladder no longer pains.
(1) Singh NK et al. Elderly Woman With Orange Urine and Purple Hands. MayoClinProc. July 2008;83(7):744.

1 comment:

Mauigirl said...

I remember the olden days when a UTI was cured by Azo Gantrisin which had the pyridium right in it - and you took it for ten days straight (and were supposed to drink tons of water with it). Urine was orange the whole time but I don't remember getting purple palms! Maybe the elderly are more prone to it.