Posted by Cam W. on April 10, 2000, at 6:42:00
In reply to topomax, posted by Susan on April 10, 2000, at 1:02:11
> Anybody experience an allergic reaction or a rash to topomax? If so, what is your dosage?
Susan - The dosage of Topamax is really no reflection of allergic reaction. It can happen at 25mg or not be noticed until you reach 200mg (although that is usually unlikely). An allergic reaction occurs when an allergen (eg Topamax) enters the body. The immune system sees this as a foreign molecule that needs to be removed and will begin to produce antibodies to recognize this intruder the next time it enters your body. This is called sensitization. The next time the Topamax enters your bloodstream the immune system recognizes it and produces and releases antibodies which attach to white blood cells (mast cells). The mast cells contain histamine and are broken open by the antibodies. The histamine causes the allergic reactions we see. Histamine has a number of properties including making the cell wall of blood vessels more permeable to white blood cells that engulf and breakdown antigens. Also, histamine causes the characteristic rash, runny nose and swollen throat of an allergic reation.
The allegic reaction can be minor and not noticed at low doses of allergen (eg Topamax), but more commonly the allergic reaction will happen on the second dose, after sensitization has taken place. The level of allergic reaction is determined by how much a threat to your body the immune system considers the allergen to be.
Antihistamines works by binding to mast cells (the white blood cells that contain histamine) and stabilize them, not allowing the antibodies to break them open as easily. This stops the symptoms of an allergic reaction from occuring.
I know that this was not your original question, but I hope it helps - Cam W.
poster:Cam W.
thread:29485
URL: http://www.dr-bob.org/babble/20000401/msgs/29497.html