Plant Allergies: Latex, Carrageenans

One in four or five Americans suffer from a misguided immunologic reaction against inoffensive substances -- allergens -- such as pollens, animal danders, foods, cigarette smoke, industrial fumes, insects and their venoms, and medications. Because these allergens stimulate the immune system at different body sites, they give rise to an enormous variety of symptoms. Allergens in the upper airways cause sneezing and nasal congestion (allergic rhinitis, including hay fever); allergens in the lower airways cause bronchoconstriction and wheezing (asthma); food allergens cause nausea, vomiting, abdominal cramps, and diarrhea; topical allergens cause contact dermatitis.

The most serious form of allergic reaction -- anaphylaxis -- occurs when an allergen enters the circulation and causes an acute, explosive release of mediators from mast cells, resulting in serious symptoms within minutes of allergen exposure. Severe anaphylaxis is a medical emergency; prompt attention is necessary to prevent death from shock or suffocation (caused by swelling of the vocal cords). Pruritus, urticaria, and bronchoconstriction are common allergic reactions, and some patients have gastrointestinal symptoms. In some cases, anaphylactic symptoms are preceded by an aura, and patients who experience recurrent anaphylaxis report that the same constellation of symptoms accompanies each attack. Treatment usually is administered as an injection of epinephrine to inhibit mediator release, open airways, and block vasodilation.

Plants are the most common source of allergens, with pollens and foods (especially tomatoes, onion, garlic, peanuts, and various fruits) heading the list. Approximately 15% of Americans have pollen sensitivity (hay fever), and many of these also have food allergies. For example, people with grass pollen allergy often cross-react to certain foods. Allergies are treated with antihistamines or, when these agents are ineffective, with inhaled corticosteroids. Severe cases are treated with immunotherapy (injection with increasing doses of the allergen). These "allergy shots" can be helpful, although protection is rarely complete. Sometimes pollen immunotherapy can reduce food hypersensitivity in children.

One common and often overlooked plant allergen is latex, an emulsion of rubber globules from the milky sap of Euphorbiaceae plants. The allergy develops when latex protein fragments come into contact with the skin or mucosa, causing contact dermatitis, pruritus, urticaria, conjunctivitis, rhinitis, asthma, and even anaphylaxis. Individuals at increased risk include latex industry workers, health-care personnel who wear latex gloves, patients who undergo frequent surgeries, atopic individuals (who have a general predisposition to allergic reactions), and, in particular, individuals with neural tube defects. Again, cross reactions are common; people with latex allergy often report allergies to avocados, chestnuts, bananas, and other fresh fruits. In some cases, latex-sensitive patients become anaphylactically allergic to fresh fruits; in other cases, the fruit allergy shows up first, followed by latex allergy on exposure to latex. Diagnosing latex allergy requires the utmost care. One patient who tested positive for multiple allergens on skin prick turned out to have latex allergy; the health-care worker who administered the skin-prick test was wearing latex gloves.

Carrageenan allergy is another difficult-to-detect plant allergy. Carrageenans are gelatinous substances obtained originally from seaweed (Irish moss), and now from several marine algae. They are commonly used as emulsifying, suspending, and clarifying agents in manufactured foods (certain dairy products, dressings, sauces), beverages, pharmaceuticals, cosmetics, and polishes. One patient undergoing a diagnostic barium procedure for gastrointestinal symptoms had an anaphylactic reaction to the barium enema solution. At first, the latex in the enema device was suspected, but the patient did not test positive to latex. Instead, she tested positive for the carrageenan used as an emulsifying agent in the barium suspension.
Ref:Tomazic VJ et al. J Allergy Clin Immunol.

asthma medication options

Asthma accounts for more absences from school than any other chronic illness and is a leading cause of visits to the doctor’s office. It is a serious disease—the rate of death from asthma is under l percent among hospitalized children, but it rises to 2 to 4 percent among adults.

Until approximately 10 years ago, asthma was defined as spastic airways or repetitive contractions of bronchial smooth muscle. A major development was the appreciation that a better definition of asthma was hyperreactive or spastic airways with inflammation. In fact, it was convincingly demonstrated that the severity of asthma correlated with the concentration of inflammatory products in the bronchial fluid of patients with asthma. In this regard, one of the most important advances in the treatment of asthma was the introduction of inhaled, or topical, steroids as first-line drugs. Before discussing inhaled steroids, I will put their role into perspective by briefly discussing the roles of other medications in the treatment of asthma.

Effective treatment of asthma entails the following four steps (not all of which are applicable to everyone):

1-Identification of causal agents
2-Avoidance of causal agents
3-Control of appearance of symptoms through medication and other strategies
4-Treatment of symptoms
There are several medications available that keep asthma symptoms from appearing or relieve them when they are present. These medications are beta-agonists, theophyllines, cromolyn sodium, leukotriene inhibitors, and corticosteroids. Except for a few over-the-counter beta-agonists, these are all prescription drugs.

beta-agonists
theophyllines

cromolyn sodium
leukotriene inhibitors
corticosteroids

Beta-agonists for treatment of asthma

Beta-agonists are a major class of medications for asthma. These drugs can be taken orally, but they are most commonly and effectively administered by operating a metered-dose, handheld, aerosol canister. They provide rapid relief of asthmatic wheezing and shortness of breath. Activating the canister releases a puff of drug-saturated aerosol, which is carried directly to the twitchy smooth muscle in the airways. This direct action quells the symptoms rapidly. Because beta-agonists work almost instantaneously, they are extremely satisfying to use, but they treat only the symptoms of asthma, not the underlying inflammation.

Theophyllines for treatment of asthma

Theophyllines are related to caffeine and work by relaxing bronchial smooth muscle, thus opening up the airways and making breathing easier. The amount of theophylline to take depends on body size and has to be determined carefully. Even then there are sometimes significant differences in reactions between like-sized individuals, so when physicians prescribe theophylline, they are likely to order a blood test that measures how much theophylline is in the blood several days after the patient starts to take it.

Cromolyn sodium for treatment of asthma

Cromolyn sodium, a chemical originally isolated from an Egyptian weed, comes in two forms: as a metered-dose aerosol or as a liquid for nebulization. It is not as effective as inhaled steroids.

Leukotriene inhibitors for treatment of asthma

Leukotriene inhibitors, which are given orally, can reduce the severity of asthma in some patients. There are several such products on the market, including Accolate, Zeileutin, and Singulaire. They can be very effective agents in some patients and should be given a serious trial in patients with chronic symptoms. They can also be considered first-line drugs.

The Use of Inhaled Steroids for Asthma

The most-potent drugs for asthma, however, are steroids, or drugs in the cortisone family. Oral or injected steroids are usually prescribed only in cases of severe asthma, especially for those at risk for hospitalization or for patients who are already hospitalized. These drugs can be life-saving; in fact, one common feature of asthma mortality is the failure to take adequate doses of steroids. Unfortunately, systemic steroids have toxicity and therefore should not be used on a regular basis unless necessary.

Approximately 25 years ago, it was found that inhalation of steroid powder in a metered-dose inhaler had significant preventive action in the management of asthma. Initially, these inhaled steroids, of which beclomethasone was the prototype, were used only as secondary or tertiary agents. Asthma specialists now realize that these drugs are first-line agents and can often manage asthma by themselves. They are also important ancillaries to beta-agonists.

Unless used more frequently than recommended, aerosol steroids do not produce the negative side effects of oral or injected cortisone and can be quite effective. While they do not deliver the amount of cortisone required for severe (but unhospitalized) asthmatics, they are extremely helpful in subacute cases. These agents include Beclovent, Vanceril, Aerobid, Azmacort, Flovent, and Pulmicort. All of these agents have advantages and disadvantages over each other, but for the most part, patients end up using the inhaled steroids that are covered by their insurance carriers.

These drugs can be given as infrequently as twice a day and sometimes achieve a better result when a spacer is provided to help in the delivery of the inhaled dose. Pulmicort is also available as a turbuhaler, and Flovent is also available as a rotodisk. Both of these methods of delivery may be more comfortable and effective for some patients. Flovent, one of the newest of these agents, is available in three different concentrations and thus can be adjusted for patients of different ages and sizes. Aerobid is unpleasant to take because it has a bad taste and may induce nausea. I therefore do not recommend it, even in the mint flavor.

Use of low doses of inhaled steroids is hardly ever associated with systemic toxicity. However, long-term use of high doses can have adverse effects. The most common of these adverse effects are local complications, including coughing, horaseness, and an inflamed throat. In addition, patients who are receiving high doses of inhaled steroids should have ocular exams once a year to rule out the development of glaucoma.

One final point about inhaled steroids is that many patients also use a beta-agonist. In such a case, the patient should first use the beta-agonist, followed by the inhaled steroid. This regimen allows the airways to open, therefore allowing better penetration of the topical steroid. Inhaled steroids are to be used for prevention and should never be used to try to manage an asthma attack.