Procedures and pharmaceutical products for use in the administration of antihistamines

#The present invention relates to methods, and pharmaceutical preparations or charges intended for use in the treatment, by inhalation, of reversible airways obstruction, as for example, in asthma, chronic bronchitis, and allergic conditions commonly known as hay fever. The invention is particularly valuable in cases where rapid relief is desired.

#The role of histamine in the mediation of bronchial asthma is controversial. Histamine has been shown to be released, along with other mediators, from the lungs of guinea pigs previously sensitized by allergen exposure, upon re-challenge with the same allergen. The injection of histamine in some animals provokes an anaphylactoid reaction which includes severe broncho-spasm. In man, the injection of histamine, or its inhalation has various effects. In normal subjects quite large doses can be tolerated with only mild visceral effects (rapid pulse, abdominal discomfort, headache, and flushing). However, in patients with asthma, chronic bronchitis, and hay fever, even very small doses of histamine, either by injection or aerosol inhalation, excite intense bronchoconstriction. Finally, it has been shown that blood histamine levels are higher in asthmatics than in non-astmatic subjects, and rise significantly following allergen induced bronchoconstriction, and in spontaneously occurring attacks. Sputum histamine levels are also elevated in patients with chronic bronchitis in exacerbation.

#These studies suggested that antihistamines might have a place in the blocking and treatment of exacerbations of these conditions. However, numerous studies have failed to show any significant benefit from antihistamine given orally, or by injection, in doses tolerable in the patient.

#The following examples illustrate the invention in more detail:

#FIve patients were studied when recovering from a severe attack of asthma. Patients 1, 2 and 3 inhaled chlorpheniramine 0.05% and patients 4 and 5 inhaled clemastine 0.05% from a Wright's nebulizer. Baseline measurements of blood pressure and FEV.sub.1 and FVC (Forced Vital Capacity) were taken and repeated at 10 minute intervals for 1 hour following inhalations of the test substances (see Table 1). No change in blood pressure was noted and the inhalation was well tolerated by all the patients.

#These studies suggested a useful degree of bronchodilatation and prompted a formal study.