Depending on the individual, allergen, and mode of introduction, the symptoms can be system-wide (classical anaphylaxis) or localized to specific body systems. Asthma is localized to the respiratory system and eczema is localized to the dermis. Late-phase response
After the chemical mediators of the acute response subside, late-phase responses can often occur. This is due to the migration of other leukocytes such as neutrophils, lymphocytes, eosinophils, and macrophages to the initial site. The reaction is usually seen 2–24 hours after the original reaction. Cytokines from mast cells may play a role in the persistence of long-term effects. Late-phase responses seen in asthma are slightly different from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils and are still dependent on activity of TH2 cells. Allergic contact dermatitis
Although allergic contact dermatitis is termed an "allergic" reaction (which usually refers to type I hypersensitivity), its pathophysiology involves a reaction that more correctly corresponds to a type IV hypersensitivity reaction. In type IV hypersensitivity, there is activation of certain types of T cells (CD8+) that destroy target cells on contact, as well as activated macrophages that produce hydrolytic enzymes. Diagnosis
Effective management of allergic diseases relies on the ability to make an accurate diagnosis. Allergy testing can help confirm or rule out allergies. Correct diagnosis, counseling, and avoidance advice based on valid allergy test results reduce the incidence of symptoms and need for medications, and improve quality of life.
By April 1973, the U.S. Food and Drug Administration approved amantadine for use in the treatment of Parkinsons disease.In 2017, the U.S. Food and Drug Administration approved the use of amantadine in an extended release formulation for the treatment of dyskinesia, an adverse effect of levodopa in people with Parkinsons disease. Veterinary misuse
In 2005, Chinese poultry farmers were reported to have used amantadine to protect birds against avian influenza. In Western countries and according to international livestock regulations, amantadine is approved only for use in humans. Chickens in China have received an estimated 2.6 billion doses of amantadine. Avian flu (H5N1) strains in China and southeast Asia are now resistant to amantadine, although strains circulating elsewhere still seem to be sensitive. If amantadine-resistant strains of the virus spread, the drugs of choice in an avian flu outbreak will probably be restricted to neuraminidase inhibitors oseltamivir and zanamivir which block the action of viral neuraminidase enzyme on the surface of influenza virus particles. However, there is an increasing incidence of oseltamivir resistance in circulating influenza strains (e.g., H1N1), highlighting the need for new anti-influenza therapies.In September 2015, the U.S. Food and Drug Administration announced the recall of Dingo Chip Twists "Chicken in the Middle" dog treats because the product has the potential to be contaminated with amantadine. References
External links

"Amantadine". Drug Information Portal. U.S. National Library of Medicine. "Amantadine hydrochloride". Drug Information Portal. U.S. National Library of Medicine.