The effect of ketotifen on aspirin-induced asthmatic reactions

[Special features of NSAID intolerance in children]

Adverse reactions to acetylsalicylic acid (aspirin, ASA) and other non-steroidal anti-inflammatory drugs (NSAIDs) are the second most important cause of adverse drug reactions (ARDs) after beta-lactams. They produce various clinical manifestations and can affect different organs. Gastrointestinal reactions (pyrosis, vomiting, gastralgia), neurological reactions (tinnitus, deafness, vertigo), blood dyscrasias, and nephrotoxic and hepatotoxic reactions are well known.NSAIDs are the drugs of choice in the treatment of chronic arthropathies and other childhood connective-tissue diseases and are also commonly used in the treatment of febrile and acute inflammatory processes. Not all NAIDs are authorized for use in the pediatric population but their spectrum of use varies according to the entity for which they are indicated and the legislation of the country. Published studies on the prevalence of aspirin intolerance in patients with bronchial asthma show a fair amount of disagreement. This may be due to (i) the method of selecting asthmatic patients for the study, which differs according to whether all asthmatic patients are included or only those dependent on corticoids; (ii) the diagnostic method used, whether based on clinical criteria or oral provocation tests, which will affect the number of patients with a diagnosis of intolerance. In children aged less than 10 years, including children with asthma, the prevalence is low, while among children and young adults aged 10-20 years old, the prevalence is estimated at 10 %. Some hypotheses attempt to explain the mechanisms through which adverse reactions to NAIDs take place. One hypothesis attributes the reaction to a reaginic immunological mechanism but this hypothesis has only been confirmed in exceptional cases. The theory of the cyclooxygenase pathway, currently the most widely accepted, is based on the ability of NSAIDs to inhibit the cyclooxygenase pathway of arachidonic acid metabolism, leading to prostaglandin depletion and an increase in leukotrienes. The discovery of two isoforms of the cyclooxygenase enzymes, COX-1 and COX-2, has represented a great advance in our understanding of the mechanism of action of NSAIDs and has also elucidated the problem of cross-reactivities. According to the theory of viral infection, aspirin-induced asthma could be caused by chronic viral infection since, after initial exposure to the virus, cytotoxic lymphocytes are produced. Their activity is inhibited by prostaglandin E2 (PGE2); aspirin and other NSAIDs block PGE2 production and allow cytotoxic lymphocytes to attack and eliminate the respiratory tract cells infected by the virus. During this reaction lysosomal enzymes and mediators are released, which could precipitate an asthmatic crisis.Clinically, five types of reaction have been identified: 1. Respiratory illness with aspirin sensitivity. 2. Aspirin-induced urticarial disease. 3. Allergic reactions to NSAIDs and aspirin. 4 and 5. Aseptic meningitis and pneumonitis due to hypersensitivity. The latter are exceptional and are published as case reports. They have never been associated with aspirin or acetaminophen and usually occur in patients undergoing prolonged treatment. Diagnosis is based on a detailed history. Skin tests are not valid and in vitro tests are not widely used. Provocation tests with aspirin and NSAIDs definitively identify sensitized patients but their indications and limitations should be kept in mind. In children, certain features of adverse reactions to NSAIDs are observed in relation to their incidence and clinical manifestations. Acetaminophen is considered the drug of choice but further studies of other alternatives in children are required.

Long-term tolerability of nimesulide and acetaminophen in nonsteroidal antiinflammatory drug-intolerant patients

BACKGROUND

Oral challenges are used to identify alternative nonsteroidal antiinflammatory drugs (NSAIDs) for patients who react adversely to drugs of this class, but challenge conditions often differ from those in which the drug will actually be used.

OBJECTIVE

To determine whether the results of oral challenges with nimesulide or acetaminophen, using cumulative administration of a single therapeutic dose while the patient is in good health, can predict the response to multiple doses of the drug during future illness.

METHODS

Follow-up interviews were conducted with 248 NSAID-intolerant subjects who had tolerated oral challenges with nimesulide and/or acetaminophen 1 to 3 years earlier. We analyzed the adverse reaction rate in light of the febrile/non-febrile nature of the condition treated and the number of doses consumed.

RESULTS

Nimesulide was tolerated by 115/122 (94.2%) of the patients who had tried it; acetaminophen by 71/75 (94.6%). A total of 8/159 (5%) patients had experienced reactions (seven urticarial and one asthmatic) to one or both drugs. Intolerance was unrelated to the nature of the condition treated or the number of doses administered, but all four patients who failed to tolerate acetaminophen and 3/7 of those who reacted to nimesulide had histories of chronic urticaria.

CONCLUSIONS

Oral challenges can reliably predict long-term NSAID tolerability in patients with previous adverse reactions to other drugs of this class, except for patients with chronic urticaria.

Direct evidence for a role of the mast cell in the nasal response to aspirin in aspirin-sensitive asthma

BACKGROUND

A subset of patients with asthma experience adverse nasoocular reactions after ingestion of aspirin or agents that inhibit cyclooxygenase. Recent evidence has implicated the leukotrienes in the nasoocular reaction, but the cellular sources and mechanism of activation are unknown. We used nasal lavage with and without a 5-lipoxygenase inhibitor, zileuton, to define the role of leukotrienes and to profile nasal cellular activation during this reaction.

METHODS

A group of eight patients with asthma shown to have adverse reactions to aspirin documented by a 15% or greater decrease in forced expiratory volume in 1 second, accompanied by an elevation in urinary leukotriene E4 after ingestion of aspirin, received aspirin or placebo in a study with a crossover design. Nasal symptoms and nasal tryptase, histamine, leukotriene, and eosinophil cationic protein levels were evaluated. Serum tryptase and urinary histamine levels were also assessed. Subjects were then randomized to receive a week of treatment with zileuton or placebo, according to a double-blind, crossover design followed by aspirin challenge and measurement of the same mediators.

RESULTS

Aspirin ingestion produced a marked increase in nasal symptoms from a baseline symptom score of 2.1 +/- 0.7 to a maximum of 8.4 +/- 1.2 (p < 0.0007). Aspirin ingestion produced a mean maximal increase in nasal tryptase of 3.5 +/- 2.6 ng/ml, whereas placebo ingestion produced a mean maximal increase of 0.1 +/- 0.2 ng/ml (p < 0.05, aspirin vs placebo). Mean maximal nasal histamine increased 1.73 +/- 1.16 ng/ml versus 0.08 +/- 0.08 ng/ml from baseline (p < 0.05, aspirin vs placebo). Aspirin produced a mean maximal increase in nasal leukotriene value of 152 pg/ml versus a 16 pg/ml decrease after placebo ingestion (p < 0.05). Zileuton treatment blocked the increase in nasal symptoms after aspirin ingestion (maximum nasal symptom score of 1.6 +/- 0.6 with zileuton vs 5.5 +/- 0.9 with placebo [p < 0.0053]). It also blocked the rise in nasal tryptase (p = 0.011) and nasal leukotriene (p < 0.05) levels after aspirin ingestion. Zileuton treatment had no significant effect on the recovery of nasal histamine.

CONCLUSION

The increase in nasal symptoms in aspirin-sensitive patients with asthma after aspirin ingestion is associated with increases in nasal tryptase, histamine, and cysteinyl leukotriene levels. This mediator profile is consistent with mast cell activation during the nasal response to aspirin and suggests that 5-lipoxygenase products are essential for the nasal response to aspirin.

Localized periorbital edema induced by aspirin

We documented localized periorbital edema in two patients with aspirin sensitivity without underlying chronic urticaria. The reaction developed 30 min after ingestion of 62.5 and 125 mg of aspirin, respectively. No systemic symptoms were observed. Other NSAIDs did not induce symptoms. These patients were able to tolerate doses of aspirin after pretreatment with terfenadine. These observations suggest that histamine plays a central role in aspirin-induced skin reaction. Despite the fact that terfenadine blocks the drug-induced reaction, this protocol should be used with caution and only where there is no feasible alternative to aspirin.

Ketotifen. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in asthma and allergic disorders

Ketotifen is an orally active prophylactic agent for the management of bronchial asthma and allergic disorders. Accumulated evidence indicates that after 6 to 12 weeks of administration, ketotifen significantly reduces respiratory symptoms and the need for concomitant antiasthmatic drugs in about 70% and 50%, respectively, of patients with mild to moderate bronchial asthma. However, absolute improvement in lung function is generally slight. Ketotifen also has pronounced antihistaminic and antianaphylactic properties which result in moderate to marked symptom improvement in the majority of patients with atopic dermatitis, seasonal or perennial rhinitis, allergic conjunctivitis, chronic or acute urticaria or food allergy. Comparative trials with established agents--notably sodium cromoglycate (cromolyn sodium) in asthma and histamine H1-antagonists in allergic disorders--indicate that ketotifen has comparable clinical utility. Unlike inhaled sodium cromoglycate, ketotifen ameliorates the symptoms of asthma, rhinitis and dermatitis when present together in atopic patients. Patient acceptance of ketotifen is good, although sedation can be troublesome in older children and adults for the initial 2 weeks of treatment. Weight gain is another notable effect in a small percentage of patients. Thus, ketotifen appears to be a useful agent for the management of allergic disorders and bronchial asthma, particularly in patients for whom oral therapy is preferred. Although a lengthy run-in period is needed in the treatment of asthma, in those patients who respond, continued reduction in the frequency and severity of symptoms and in the use of additional antiasthmatic drugs can be anticipated.

The abnormal in vitro response to aspirin of platelets from aspirin-sensitive asthmatics is inhibited after inhalation of nedocromil sodium but not of sodium cromoglycate

1. Blood platelets from patients with aspirin-sensitive asthma (ASA) generated cytotoxic mediators in the presence of aspirin. This abnormal in vitro response to aspirin was abolished within 1 h after nedocromil sodium inhalation but not after sodium cromoglycate inhalation. 2. Platelets recovered this reactivity to aspirin by 12 hours after nedocromil sodium treatment of ASA-patients. 3. The in vitro reactivity to aspirin of ASA platelets isolated before inhalation was inhibited in the presence of serum isolated 15 and 60 min after nedocromil sodium inhalation.

Inhaled lysine-aspirin as a bronchoprovocation procedure in aspirin-sensitive asthma: its repeatability, absence of a late-phase reaction, and the role of histamine

Inhalation of an aerosolized solution of lysine-aspirin has previously been described as a safer technique than oral challenge with aspirin for the diagnosis of aspirin-sensitive asthma. We describe a modification of this method that involves inhalation of serially doubling incremental concentrations of lysine-aspirin by a standardized technique and allows construction of concentration-response curves. In 11 subjects with asthma, mean (SEM) age 48.2 (2.9) years, the geometric mean (range) provocation concentrations of histamine and lysine-aspirin required to produce a 20% decrease in FEV1 from baseline were 0.6 (0.04 to 3.2) and 48.3 (15.5 to 219) mg/ml, respectively. No relationship was found between these values. In seven of nine subjects investigated on two consecutive occasions, bronchoconstriction with lysine-aspirin was repeatable to within a single doubling concentration difference. Bronchoconstriction provoked by lysine-aspirin was more rapid than with oral aspirin and was not followed by any late asthmatic reaction or increase in nonspecific airway hyperresponsiveness. In six subjects, premedication with the selective H1 histamine-receptor antagonist, terfenadine, had no significant effect on bronchoconstriction provoked by inhaled lysine-aspirin, indicating little role for release of histamine in the response. We conclude that inhalation of lysine-aspirin may be used as a bronchoprovocation procedure for the diagnosis and investigation of aspirin-sensitive asthma.

Analgesics, allergy and asthma

Intolerance to analgesics is common in patients with bronchial asthma, nasal polyps and urticaria. Symptoms of intolerance resemble those of allergy, but the events precipitating them can rarely be traced to reactions between the drug and a specific antibody or sensitised T-lymphocytes. In 8 to 20% of adult asthmatics, aspirin and several other analgesics provoke asthmatic attacks, probably through inhibition of cyclo-oxygenase. This is a distinct and important clinical syndrome with a specific history, course and clinical presentation and a number of unique peculiarities which still require elucidation at the biochemical level. Up to 40% of patients with chronic urticaria develop an obvious increase in weals and swelling after taking aspirin. These reactions occur only when urticaria is active, and though the reason for them is not known, it appears that different mechanisms may be responsible in different patients. Skin reactions other than exacerbation of chronic urticaria are less common, but may create serious clinical problems. The clinical background of a patient often determines the type of adverse response to an analgesic. Thus, in certain individuals, analgesics can produce anaphylactic reactions and/or urticaria, probably through an immunological mechanism, while in some asthmatics they precipitate bronchoconstriction, probably through inhibition of bronchial cyclooxygenase. Study of untoward reactions to analgesics not only leads to safer pharmacotherapy, but it also offers a fascinating model for better understanding of some diseases.

Aspirin-sensitive asthma

Aspirin intolerance is particularly common in asthmatic patients who additionally have chronic rhinitis and/or nasal polyps. These individuals differ in several respects from patients who experience urticaria and/or angioedema after aspirin administration, and differing mechanisms may be involved. Data regarding the latter are indirect and incomplete, but suggest that ASA-sensitive asthma is most likely to be related in some manner to the capacity of ASA to inhibit cyclooxygenases, enhanced lipoxygenase metabolism perhaps playing a crucial role. Current research employing ASA "desensitization" may help to elucidate these enigmas.