Proventil HFA provides protection from exercise-induced bronchoconstriction comparable to proventil and ventolin.

INTRODUCTION: During the 1970s, scientists suggested that the growing use of chlorofluorocarbons (CFCs) was contributing to depletion of the stratospheric ozone layer with potentially harmful results. A committee on the ozone layer organized the preparation of the Montreal Protocol. This protocol mandated the cessation of production and use of CFCs by January 1, 1996. The primary exemption to this ban is for the use of CFCs as propellants in metered dose inhalers (MDIs) for the treatment of asthma. Suitable replacement hydrofluoroalkane (HFA) propellants, such as HFA-134a, for use in MDIs have been identified. Albuterol, a selective beta-adrenergic agonist, currently widely available for inhalation asthma therapy, has been reformulated in HFA-134a (Proventil HFA). OBJECTIVE; To compare the efficacy of Proventil HFA to Ventolin, Proventil, and placebo (HFA-134a) MDI in protecting asthmatic patients from exercise-induced bronchoconstriction. METHODS: This was a randomized, single-blind, placebo-controlled, 4-period crossover study of asthmatic patients with documented exercise-induced broncho-constriction. Twenty patients self administered two puffs of either Proventil HFA, Ventolin, Proventil or placebo, from an MDI, 30 minutes prior to performing a standardized exercise challenge at the study site. Spirometry was performed predose and 5, 10, 15, 30, 45, 60, 75, and 90 minutes after completion of the exercise challenge. Heart rate and blood pressure were measured just prior to spirometry and a 12-lead ECG was performed 15 minutes after completion of the exercise challenge for measurement of the QT corrected interval. RESULTS: The primary efficacy variable was the smallest percent change from the predose FEV1 following exercise. The smallest percent change from predose FEV1 for Proventil HFA was 2.0 +/- 9.9 SD, similar to the 2.0 +/- 11.4 SD for Ventolin, and the 3.6 +/- 10.2 SD for Proventil. The smallest percent change from predose FEV1 for each of the active treatments was significantly different from placebo, -23.7 +/- 14.5. Twelve of the patients had a > or = 20% fall in FEV1 post-exercise with placebo pretreatment, but only 1, 1, and 0 had > or = 20% FEV1 falls after treatment with Proventil HFA, Ventolin, and Proventil respectively. Changes in heart rate, blood pressure and QT corrected interval were similar for the three active treatments following exercise. CONCLUSIONS: Proventil HFA provides protection against exercise-induced bronchoconstriction comparable to Ventolin and Proventil and protection superior to placebo. Proventil HFA has a safety profile similar to Ventolin when used to prevent exercise-induced bronchoconstriction.

Treatment of cat allergy with T-cell reactive peptides.

We induced in allergic humans the counterpart of murine experimental T-cell tolerance. T-cell lines from cat-allergic humans were used to map T-cell epitopes for the principal allergen of cat dander, Fel d 1. Two peptides of 27 amino acids each were synthesized to contain the dominant epitopes (ALLERVAX CAT). After a safety trial, we carried out a blinded study of the dose required for efficacy. We randomly divided 95 cat-sensitive patients into placebo, 7.5 micrograms, 75 micrograms, and 750 micrograms groups. Patients received a subcutaneous injection weekly for 4 wk. Before and after treatment, patients were exposed in a room inhabited by live cats and scored by nose and lung symptoms. Baseline nasal and lung scores (+/-SEM) were 6.2 +/- 0.56 and 5.4 +/- 0.73 in the 750 micrograms group; 7.8 +/- 0.53 and 4.7 +/- 0.68 in the placebo group. Six weeks after treatment, scores adjusted for baseline differences were reduced in the 750 micrograms group: -2.3 +/- 4.9 and -2.3 +/- 0.59 compared with -0.84 +/- 0.50 and -0.85 +/- 0.62 in the placebo group. The 75 micrograms group showed intermediate effects and the 7.5 micrograms group no effect. Linear trend analysis indicated a significant dose response effect: p = 0.05 for nose and 0.03 for lung symptoms. Allergic side effects occurred an hour or more after the first 750 micrograms dose in 16 of 24 patients but required little or no treatment with one exception. T-cell reactive treatment peptides safely improved allergic responses to cats.

Factorial dose-response studies using frequency and magnitude of dose.

In the early stages of traditional drug development, the frequency of dosing (e.g., QD, BID, etc.) is typically determined by the pharmacokinetic properties of a compound. After an appropriate dose frequency is chosen, the magnitude of dose is then evaluated via parallel-group dose-response trials. For some drugs, however, blood levels at any given time may not be accurate predictors of clinical response, or the drug may not be absorbed systemically. In those instances, we propose the use of a factorial dose-response trial that simultaneously evaluates frequency of dosing and magnitude of dose. We consider this approach to selecting an appropriate dosing regimen to be more scientifically founded and more cost-effective, than independent evaluation of dose and frequency through separate clinical trials. Some design considerations and statistical analysis strategies for these factorial trials are presented in this paper.

On assessing interrater agreement for multiple attribute responses.

New methods are developed for assessing the extent of interrater agreement when each unit to be rated is characterized by a (possibly empty) subset of a specified set of distinct nominal attributes. For such multiple attribute response data, a two-rater concordance statistic is derived, and associated statistical inference-making procedures are provided. This concordance statistic is corrected for chance agreement by using an underlying hypergeometric model. Numerical examples are given to illustrate the proposed methodology, and comparisons to other agreement statistics (e.g., kappa) are made.

Some analysis strategies for three-period changeover designs with two treatments.

Alternative analysis strategies for the three-period crossover design with two treatments are discussed in this paper. One analysis strategy involves a parametric model that incorporates the effects of interest. To implement this method, one usually assumes that the covariance structure for the data has the sphericity, or circularity, property. Alternative approaches that do not require this assumption are described. They are based on the parametric and non-parametric analysis of appropriate within-subject linear functions of the data. The advantage of these methods is that one only needs the assumption that the resulting linear functions for the respective subjects are independent and have a common distribution. The parametric approach also requires normality of the resulting within-subject linear functions for small sample situations. An extension of the non-parametric method is considered for cases in which the treatment sequences are randomly assigned within strata. The various methods are illustrated for a three-period crossover design involving two strata with randomly assigned treatment sequences of the form A:B:A and B:A:B.