Uses Decongestants are used primarily in the treatment of hay fever, vasomotor rhinitis, and intrinsic rhinitis. They also provide some relief of allergy of the stomach and intestines (gastrointestinal allergy) and occasionally of hives. For treating hives, however, drugs such as epinephrine and ephedrine are used more widely. Representative Drugs Pseudoephedrine hydrochloride (D-Feda, Novafed, and Sudafed) are probably the most widely used oral decongestants. Others are ephedrine, phenylephrine, phenylpropanolamine (Propadrine), and pseudoephedrine sulfate (Afrinol). Ephedrine, which stimulates the central nervous system more than do such drugs as pseudoephedrine, is used primarily as a bronchodilator. Pseudoephedrine has fewer side effects than ephedrine. Although it is active as a bronchodilator, it is less effective than other drugs in treating asthma. Commonly used intranasal preparations are naphazoline (Privine), oxymetazoline (Afrin), phenylephrine (Neo-Synephrine), tetrahydrozoline (Ty-zine), and zymetazoline (Otrivin). Side Ettects and Precautions Among the side effects of oral preparations, as well as the effects of overdoses of intranasal preparations, are nervousness, dizziness, nausea, awareness of heartbeat (usually rapid), and occasionally stimulation of the central nervous system. Other effects, which usually occur among children, are high blood pressure, slow heart rate, ir regular heart rhythm, and low blood pressure. Children have also been known to experience severe side effects, including sweating, drowsiness, deep sleep, coma, hypotension, and slow heart rate. Be­cause of the effects listed above, caution should be exercised when these drugs are used in people with heart disease, high blood pressure, sugar diabetes, thyroid disease, or any combination of these diseases, or those taking drugs (also known as "mood elevators") of the tri­cyclic class. Patients taking the monoamine oxidase (MAO) inhibitor class of antidepressive drugs should not also use decongestant drugs. Intranasal agents require additional precautions. For example, they should be used only in treating illnesses that are short and relatively severe, that is, illnesses that do not exceed five days in duration. Pro­longed use often causes a "rebound" phenomenon in which, while more and more of the drug is required, the desired effect of the drug becomes increasingly less. More frequent and larger doses of a drug are used, accompanied by the twin risks of overdose and toxicity. Prolonged use causes rhinitis medicamentosum, a condition in which the mucous membranes of the nasal passages become red, boggy, or pale gray and edematous (swelling with fluid between the cells) and in which the inflamed membranes are indistinguishable from other forms of chronic inflammation of the nose, such as year-round hay fever (perennial allergic rhinitis). Topical nasal decongestant solu­tions quickly become contaminated with bacteria and fungi after use, and for this reason, may be sources of infection. Some rules to follow in using spray decongestants are: 1. Rinse the spray tip or dropper in hot water after each use. 2. Do not place the spray tip or dropper inside the nose. 3. Confine use of a particular applicator to one person. 4. Discard the medication and its container when the medica­tion is no longer needed. Something over which people have no control, but which they should be aware of, is that most topical nasal decongestant solutions inter­act with aluminum and thus should not be stored in containers made wholly or in part of the metal. Bronchodilators Uses Bronchodilators are used primarily in treating asthma, but they are also used to treat chronic bronchitis and emphysema, diseases of the lung which chronically obstruct the air passages, as well as to treat bronchiectasis, in which dilatations occur in the air passages of the lungs. Some bronchodilators are useful in alleviating several forms of hives. Epinephrine was the first drug chosen for treating allergic or allergylike responses involving more than one body system, for exam­ple, the simultaneous occurrence of hives and asthma. Another bron-chodilator is aminophylline, which is useful as a supplemental treat­ment in some cases of systemic reaction. Representative Drugs Three classes of bronchodilators are currently being used: adre­nergic agonists (also known as sympathomimetic drugs); methylxan-thines; and anticholinergics (also known as parasympatholytic drugs). Anticholinergic drugs are now being tested and have not yet been ap­proved by the Food and Drug Administration. Other drugs now being tested are alpha adrenergic agonists and prostaglandins.

Allergenic extracts contain allergenic materials that are used in the diagnosis and treatment of allergic people. These extracts are prepared by: (1) grinding and defatting the material; (2) extracting the allergenic component into an extraction fluid, usu­ally buffered saline; (3) dialyzing the extract; and (4) sterilizing the end product. Two common methods of standardizing an allergenic extract are weight by volume and protein nitrogen unit. Neither of these methods may necessarily reflect the true allergenic potency of the extract. Weight by volume (wt/v) is the amount of dry material in a given volume of extracting fluid; for example, a 1:10 dilution is prepared from 10 grams of material in 100 milliliters (ml) of extracting fluid. Protein nitrogen unit (PNU) is the nitrogen content of the protein in an extract. The extracts used for skin tests by the prick or the scratch method are usually prepared 1:10 to 1:20 weight by volume in 50 percent glycerin, and for intradermal testing, 1:1,000 weight by volume or 400 to 1,000 PNU/ml. Allergenic extracts lose their potency over time or, especially, at higher temperatures. For this reason, they should always be refrigerated. The extracts used in im­munotherapy are prepared at several levels of increasing dilution; treatment begins with a dilute solution, and gradually the quantity and concentration are increased. Allpyral is another type of allergenic extract used in immuno­therapy. This extract is prepared by a different method, one designed to slow the rate of allergenic absorption following injection of the extract into a patient. The allergenic materials are extracted along with the organic solvent pyridine; then the solution is precipitated by alum. After removal of the excess pyridine and alum, the allergenic precipitate is again suspended in saline. The advantages of using allpyral extracts are, first, that fewer injections are needed and, second, that larger amounts of allergenic materials can be adminis­tered, with the lesser risk of allergic reaction. The main drawback is the uncertainty about the efficacy of the extract; it has not been clearly established that allpyral extracts are as effective as conven­tional allergenic ones. Several newer allergenic extracts may be marketed in the near future. Among these are the so-called gluteral dahyde-linked polymerized type, which induce a good protective immune response with less allergic side effects. They also require considerably fewer injections.

Certain medications are administered as liquids or as inhalants in canisters triggered to deliver a predetermined amount of medication. These medications often provoke fewer side effects than do similar drugs taken orally. In recent years, pharmaceutical companies have concentrated on providing drugs that se lectively cause the airways to open (bronchodilation) but which do not stimulate the heart to beat faster. Another goal is to lengthen the duration of action of the drugs. Many can be diluted with sterile water or saline solution and admin­istered with a pump (such as a Maximist) or a bulb nebulizer. Al­though positive pressure ventilators such as IPPB machines are another way of delivering a medication, they have not proved more effective than other methods of treating asthma. They are also considerably more expensive. Commercially available products are pressured and aerosolized much like a deodorant, and are often con­veniently pocket-sized. Because they can be carried inconspicuously, some patients tend to overuse them.

Aspergillus is a genus of fungi that belongs to the class Fungi Imperfecti. Several species are saprophytic; that is, they obtain food by absorbing dissolved organic material. They may cause allergic reactions, however, such as asthma and hay fever in sensitized persons. Aspergillus can also grow in the lungs, producing a tumorlike mass called an aspergilloma. Still another condition associated with this fungus is a disease called pulmonary allergic aspergillosis. Patients with this condition have symptoms of asthma, highly elevated levels of allergic (IgE) antibodies, and specific IgE and IgG antibodies against the aspergillus, plus eosinophilea. See also Allergic broncho­pulmonary aspergillus; Fungi.

Serotonin is a body chemical that causes a variety of effects such as contraction of smooth muscle; it plays a role in anaphylactic reactions in several species of animals, but its role in allergic reactions in humans is not yet known.

An idiosyncratic reaction is similar to sys­temic allergic reaction, but in this type, allergic mechanisms cannot be demonstrated. Keagin Reagin is a term used to describe allergic antibodies of the IgE type.

, is President of the American Academy of Allergy and Immunology and former Chairman of the Medical Advisory Council of the Asthma & Allergy Foundation of America. He is a professor of internal medicine and microbiology at the St. Louis University School of Medicine. John E. Salvaggio, m.d., is Henderson Professor of Medicine at Tu-lane University School of Medicine. He has published and lectured extensively on immunology and related medical subjects. Harold S. Novey, m.d., is clinical professor of medicine at the Uni­versity of California, Irvine, and Chief of the Division of Allergy-Immunology, Department of Medicine, University of California, Irvine, Medical Center. Thomas M. Golbert, m.d., is assistant clinical professor of medicine at the University of Colorado School of Medicine. He has a private practice in allergy and clinical immunology. William R. Solomon, m.d., is a professor of internal medicine at the University of Michigan Medical School. Manuel Lopez, m.d., is assistant clinical professor of medicine at Tulane University Medical School and director of the Immunology Diagnosis Laboratory in Pensacola, Florida. David A. Levy, m.d., is professor of biochemistry and medicine at The Johns Hopkins University. He has lectured and published on the mechanism of immediate hypersensitivity. Gail G. Shapiro, m.d., is clinical associate professor of pediatrics at the University of Washington, Seattle, and a frequent writer on allergy-related subjects. Sheldon L. Spector, m.d., is head of the section in allergy of the National Jewish Hospital and Research Center, Denver, Colorado, and associate professor of medicine at the University of Colorado Medical Center.

It is indeed possible that you are experiencing an allergic reaction, perhaps because of the eye-drop solution used. The best way to de­termine this is to avoid such use for a period of time, say until your eves clear up If you then resume use of the product and your eyes again smart, burn, or swell, it is likely that you are allergic to the product.

. Given by injection, epine­phrine or terbutaline are helpful, especially in treating young children. These drugs may have to be avoided, or at least used cautiously, by older people susceptible to cardiac problems. Intra­venous therapy has the advantage of better controlling the admin­istration of bronchodilators and ensuring that enough fluid is present to remove liquid secretions. After the mucus plugs are loosened, postural drainage becomes more effective. A common mistake is to stop intravenous therapy prematurely. The patient often urges the physician to discontinue this therapy, but the physi­cian should not do so until certain that the maximum benefit has been achieved. Only at this time should oral therapy be instituted.