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 developing latex

allergy because of their frequent exposure to latex products.

Other groups at risk for developing latex allergy are workers in

businesses that manufacture latex products; patients with spina

bifida; and people with allergies to avocado, potato, banana,

tomato, chestnuts, kiwi fruit, and papaya.133

Three types of reactions to latex have been described: irritant

contact dermatitis, allergic contact dermatitis (chemical sensitivity dermatitis), and immediate hypersensitivity.133,134

Irritant contact dermatitis is the most common reaction to

latex and manifests as dry, itchy, irritated areas of the skin. This

is not a true allergic reaction to latex.133

Allergic contact dermatitis is a delayed hypersensitivity reaction caused by exposure to chemicals added during the processing

and manufacturing of latex. A rash, similar to that seen with poison ivy, usually begins 24 to 48 hours after exposure and may

progress to oozing blisters.133

Immediate hypersensitivity to proteins in the latex is an

IgE-mediated allergic response. The reaction can begin within

minutes of exposure to latex or occur hours later. Symptoms

vary from mild skin redness, hives, and itching to respiratory

involvement (runny nose, sneezing, itchy eyes, trouble breathing,

asthma). Rare cases of anaphylactic shock have been described.133

Reports of the prevalence of latex allergy vary from 1% to 6%

of the general population and 8% to 12% of health care workers. Latex allergy is diagnosed by obtaining an accurate description of the reaction and establishing a temporal relationship

to latex exposure. Diagnostic kits are available to detect latex

antibodies as well as to aid in the diagnosis of allergic contact

dermatitis.133,134

Health care practitioners, particularly those in settings in

which IV or intramuscular medications are administered, may

be faced with preparing parenteral products for a latex-allergic

patient. This often poses a challenge because latex is in many

of the materials used to prepare parenteral products (e.g., rubber stoppers on medication vials, injection ports on IV bags,

rubber plungers for syringes, IV transfer sets).133,134 Many manufacturers are now preparing products in a latex-free form,

which simplifies drug preparation. Furthermore, manufacturers of medical devices are now required to identify on their

labels which products have natural latex and which have dry

natural rubber.134 Many institutions have instituted policies on

the preparation of parenteral products for the “latex-sensitive”

person. Readers are referred to these references for the details of

these procedures.135,136

PREVENTION AND MANAGEMENT

OF ALLERGIC REACTIONS

CASE 3-8

QUESTION 1: A.M., a 40-year-old woman, is hospitalized

with a diagnosis of community-acquired pneumonia. Her

medical history is noncontributory except for an uneventful course of ampicillin 6 months before admission for an

ear infection. A.M. is empirically treated with cefuroxime

0.75 g IV every 8 hours. On day 2 of therapy, she develops

a raised pruritic maculopapular rash on her back, abdomen,

and upper extremities. Antacid, docusate sodium, albuterol

by metered-dose inhaler, and multivitamins were initiated

on the same day as the cefuroxime. How should A.M.’s allergic reaction be managed? How might her allergic reaction

have been prevented?

When examining methods to prevent allergic reactions, three

possibilities exist: (a) the patient has unknowingly been sensitized to a drug and experiences an allergic reaction on receiving

the same or a similar drug again; (b) the patient has a history of

an allergic reaction to a medication and mistakenly receives the

same or a similar medication a second time and again develops an allergic reaction; and (c) the patient has a history of

an allergic reaction to a medication and intentionally receives

the same or similar medication again. As in the first situation,

A.M.’s allergic reaction was unpredictable and, therefore, could

not be prevented. To prevent future allergic reactions (i.e., the

second situation), however, A.M.’s reaction should be well documented in the medical chart and pharmacy records. In addition,

all patients should undergo a thorough drug history on hospitalization. Careful attention should be paid to differentiating drug

intolerance (e.g., stomach upset) from true allergic reactions,

and any allergic reactions elicited during an interview should be

documented appropriately. Adequate communication of allergic

reactions is the single most important method of preventing their

occurrence.

As described earlier, the first step in managing an allergic reaction is to determine its cause. Given A.M.’s history of exposure

to ampicillin, the timing of the reaction, and the low frequency

of allergic reactions to her other medications, cefuroxime is the

most likely candidate. Second, a decision regarding whether to

stop the suspect drug should be made. This decision must be

based on the severity of the reaction, the condition being treated,

and the availability of suitable alternatives. When possible, an

equally effective alternative drug should be substituted for the

suspect agent, preferably one that is immunologically distinct to

avoid cross-sensitivity (see Case 3-1, Question 4, for a discussion

of cross-reactivity).137 If a suitable alternative exists, the offending

agent should be stopped and the reaction treated symptomatically if necessary. In the case of A.M., another antimicrobial (e.g.,

azithromycin, clarithromycin, trimethoprim-sulfamethoxazole)

could be substituted for cefuroxime (Chapter 64, Respiratory

Tract Infections) and her symptoms treated with an oral or parenteral antihistamine, as well as a low-potency topical corticosteroid if necessary.

Some cases are described by the third situation: a patient

develops an allergic reaction (or has a well-documented history

of drug allergy), and it is inappropriate or not possible to change

to an alternative drug. If the sensitivity reaction is severe or

life-threatening, desensitization should be considered (Case 3-9,

Questions 1 and 2); premedication to prevent or minimize anaphylaxis is not effective.30 If the reaction is minor (e.g., pruritus, rash, or GI symptoms), premedication or management of

62 Section 1 General Care

the reaction with antiallergy medications (e.g., antihistamines)

might be sufficient to allow completion of therapy. It is rare in

such cases for the reaction to progress to more serious allergic

symptoms such as anaphylaxis137; however, suppression of allergic symptoms should be undertaken cautiously because many

immunologic reactions are not IgE mediated and may progress

to serious reactions, despite treatment. In