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Biomedical subjects

L Hendeles

Publications and source records attributed to L Hendeles.

At least 37 records · Page 2Linked to original sources
PubMed1995

Theophylline attenuation of airway responses to allergen: comparison with cromolyn metered-dose inhaler.

BACKGROUND: The purpose of this study was to compare the protection afforded by individualized doses of theophylline and a cromolyn metered-dose inhaler (MDI) during allergen challenge. METHODS: The study design was randomized, double-blind, and crossover. Responses to inhaled allergen were measured in 16 subjects with allergic asthma (age range, 18 to 35 years) after 7 days of treatment with either placebo, once daily slow-release theophylline producing a mean +/- SD serum concentration of 16 +/- 5 micrograms/ml during the late phase, or 2 mg of cromolyn administered by MDI four times daily. Forced expiratory volume in 1 second was measured at frequent intervals, and airway responsiveness to histamine was measured before and 3 hours after allergen challenge. RESULTS: The mean +/- SD maximum decrease in forced expiratory volume in 1 second during the late phase was 30% +/- 14% during placebo treatment, 16% +/- 13% during theophylline treatment, and 13% +/- 14% during cromolyn treatment (placebo vs theophylline and cromolyn, p = 0.0001; theophylline vs cromolyn, p = 0.1). The geometric mean fold increase in airway responsiveness was 3.0 +/- 1.7 during placebo treatment, 1.7 +/- 1.7 during theophylline treatment, and 1.5 +/- 1.6 during cromolyn treatment (placebo vs theophylline and cromolyn, p = 0.0001; theophylline vs cromolyn, p = 0.1). CONCLUSIONS: Theophylline, when administered once daily as a slow-release formulation, was as effective as cromolyn, administered four times daily through an MDI, in attenuating airway responses to inhaled allergen. The protection afforded by both treatments, however, was modest when compared with the results of similar studies with inhaled corticosteroids or other cromolyn formulations that deliver more drug to the lungs than the MDI available in the United States.

Adolescent↗
PubMed1994

Clinical pharmacology of pancreatic enzymes in patients with cystic fibrosis and in vitro performance of microencapsulated formulations.

Improving protein and fat absorption in patients with cystic fibrosis relates to the amount of biologically active enzyme reaching the duodenum. Microencapsulated formulations are more effective than conventional products but differ in content, ability to retard acid inactivation and the pH at which they release enzymes. Contaminants in these products contribute to hyperuricosuria.

Adolescent↗
PubMed1994

Bioequivalence of a generic slow-release theophylline tablet in children.

OBJECTIVE: To determine whether a generic slow-release theophylline tablet (manufactured by Sidmak Laboratories, Inc.) is therapeutically equivalent to a proprietary theophylline tablet, Theo-Dur, in children. DESIGN: Prospective, randomized, double-blind, crossover trial. SETTING: Multicenter clinics. PATIENTS: 38 children, 6 to 16 years of age, with asthma. INTERVENTIONS: Individualized doses of Theo-Dur or generic tablet every 12 hours for 5 days. MEASUREMENTS AND MAIN RESULTS: During the last 24 hours of each regimen, theophylline serum concentrations were measured serially and a standardized exercise stress test was performed at 24 hours (trough serum concentration). Neither formulation effectively blocked the response to exercise; the maximum decrease in forced expiratory volume in the first second was 26.1% +/- 18.9% with Theo-Dur and 24.8% +/- 19.7% with the generic product (p = 0.68; beta = 0.08). The mean +/- SD peak serum concentrations were 18.0 +/- 3.0 micrograms/ml with Theo-Dur and 18.7 +/- 3.7 micrograms/ml with the generic tablet; the trough serum concentration was < 10 micrograms/ml in 15 subjects after administration of Theo-Dur and in 20 subjects after administration of the generic product. There were no significant differences in relative extent of absorption or the time to reach peak serum concentration. CONCLUSIONS: This generic formulation and Theo-Dur are bioequivalent in children. However, these results cannot be extrapolated to slow-release theophylline formulations that have not been approved by the U.S. Food and Drug Administration as equivalent to Theo-Dur.

Adolescent↗
PubMed1993

Does aminophylline benefit adults admitted to the hospital for an acute exacerbation of asthma?

OBJECTIVE: To determine the effect of adding intravenous theophylline (administered as aminophylline) to nebulizations of albuterol and intravenous methylprednisolone in adults hospitalized for acute asthma. DESIGN: Randomized, placebo-controlled, double-blind study. SETTING: Inpatient service of a tertiary-care, university teaching hospital. PATIENTS: 21 adults (22 to 48 years old)--10 in the aminophylline group and 11 in the placebo group. INTERVENTIONS: Nebulized albuterol, 2.5 or 5.0 mg every 0.5 to 4 hours; intravenous methylprednisolone, 60 mg every 6 hours; and either individualized doses of aminophylline or placebo for 48 hours. MEASUREMENTS: Forced expiratory volume in 1 second (FEV1), the number of "as needed" albuterol nebulizations and total dose, asthma symptom scores, and adverse effects. RESULTS: At admission from the emergency department, the mean +/- SD baseline FEV1 was 49% +/- 19% of the predicted value in the aminophylline group and 43% +/- 13% of the predicted value in the placebo group. The improvement in FEV1 at 3 hours was greater in the aminophylline group (29% +/- 23% compared with 10% +/- 10% in the placebo group; mean difference, 19 percentage points; 95% CI, 3 to 35 percentage points; P = 0.023). At 48 hours, FEV1 was 75% +/- 19% of the predicted value in the aminophylline group and 58% +/- 15% of the predicted value in the placebo group (mean difference, 17 percentage points; CI, 0.2 to 34.8 percentage points; P = 0.048). Aminophylline-treated patients required fewer nebulizations of albuterol (10.3 +/- 3.8 compared with 16.4 +/- 5.3; mean difference, -6.1; CI, -10.3 to -1.8) and less total dosage (34 +/- 16 mg compared with 70 +/- 34 mg; mean difference, -36 mg; CI, -60.6 to -11.3 mg P = 0.02). No statistical differences were observed in asthma symptom scores or frequency of adverse effects. CONCLUSIONS: Individualized doses of intravenous theophylline added to frequent nebulizations of albuterol and intravenous methylprednisolone appear to benefit adults admitted to the hospital with acute asthma and are well tolerated when serum concentrations are maintained in the therapeutic range.

Acute Disease↗
PubMed1993

Efficacy of intravenously administered theophylline in children hospitalized with severe asthma.

PURPOSE: To determine whether intravenously administered theophylline, when added to frequently nebulized albuterol and intravenously administered methylprednisolone, benefits children hospitalized with severe asthma. DESIGN: Prospective, randomized, placebo-controlled, parallel-group, double-blind study. SETTING: Inpatient pediatric service at a tertiary-care teaching hospital. PATIENTS: Twenty-one children 5 to 18 years of age. INTERVENTIONS: All patients received 2.5 to 5.0 mg of nebulized albuterol every 20 minutes to every 6 hours, intravenously administered methylprednisolone (1 mg/kg every 6 hours), and either intravenously administered theophylline (as aminophylline) or placebo for 36 hours. Serum theophylline concentrations were maintained between 55 and 110 mumol/L (between 10 and 20 micrograms/ml) by adjusting loading doses and continuous infusion rates. MEASUREMENTS AND MAIN RESULTS: Forced expired volume in 1 second (FEV1) and clinical score were measured at 0, 1, 3, 6, 12, 24, and 36 hours after the start of each individual study. The total number of nebulizations, total albuterol dosage, adverse effects, and duration of hospital stay were recorded. Twelve children received theophylline and nine received placebo. The two groups did not differ significantly in age, sex, or baseline FEV1. In both groups, clinical score significantly improved from baseline by 12 hours, and FEV1 by 24 hours (p < 0.05). There were no significant differences between the groups in FEV1 or clinical score at any of the measured time points. There were no significant differences in rate of improvement in FEV1, total number of nebulizations, total albuterol dosage, or duration of hospital stay. Adverse effects were mild and infrequent and did not differ significantly between the two groups. CONCLUSIONS: Theophylline, at therapeutic concentrations, did not additionally benefit children hospitalized with severe asthma who were being treated frequently with nebulized albuterol and with methylprednisolone intravenously.

Administration, Inhalation↗
PubMed1993

Emergency department treatment of severe asthma. Metered-dose inhaler plus holding chamber is equivalent in effectiveness to nebulizer.

STUDY OBJECTIVE: To compare the effectiveness of administration of albuterol by nebulizer or by a metered-dose inhaler having a holding chamber attachment (hereafter "inhaler") for treatment of acute asthma in an emergency department (ED). DESIGN: A randomized, double-blind, placebo-controlled intervention study conducted at two sites. SETTING: The EDs of a large municipal hospital and a university teaching hospital. PATIENTS: Thirty-five patients 10 to 45 years of age seeking treatment at an ED for acute asthma. INTERVENTIONS: Patients were randomly assigned to receive either albuterol by nebulizer plus placebo by inhaler (n = 20) or albuterol by inhaler plus placebo by nebulizer (n = 15). The dose was repeated every 30 min until the FEV1 was at least 80 percent of predicted, the patient became asymptomatic, or 6 doses had been given. MEASUREMENTS AND RESULTS: All references in this article to spirometric measurements of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and peak expiratory flow rate (PEFR) represent percentages of the predicted normal value. No significant (p > 0.58) differences occurred in baseline mean FEV1, FVC, or PEFR for the two groups. For both groups, significant improvement occurred in mean FEV1 at 30 min (p < 0.02) and at 60 min (p < 0.02), and in maximum mean FEV1 (p < 0.001). However, no significant (p > 0.6) differences occurred between groups in mean FEV1, FVC, or PEFR at 30 and 60 min, or in maximum improvement attained. The sample size was sufficiently large to detect a 12 percent difference in improvement with a power of 90 percent. Thirty-three of 35 patients were treated successfully with the study protocol, became asymptomatic, and were discharged home. One patient from each group required further treatment. CONCLUSIONS: There was no detectable difference in effectiveness of albuterol administered by nebulizer or the inhaler system for treatment of acute asthma. There was no detectable difference in effectiveness of albuterol administered by nebulizer or the inhaler system for the treatment of acute asthma when the dose was titrated to clinical response. When compared with nebulizer, the metered-dose inhaler with holding chamber delivers a full dose of albuterol more quickly and at no higher cost.

Administration, Inhalation↗
PubMed1992

The effect of inhaled gallopamil, a potent calcium channel blocker, on the late-phase response in subjects with allergic asthma.

The effect of gallopamil on the late-phase response to inhaled allergen was evaluated in six young adults with allergic asthma in a crossover manner. During 2 study days, subjects received 20 mg of inhaled gallopamil or placebo 30 minutes before challenge with the same dose of allergen. In addition, a histamine challenge was performed 1 1/2 hours before and 24 hours after allergen challenge. On 2 additional study days, in the absence of allergen, basal airway responsiveness to histamine was measured before and after gallopamil or placebo administration. During the early phase, the mean +/- SD decrease in FEV1 was 28.0% +/- 11.3% after placebo and 25.1% +/- 8.4% after gallopamil administration (p greater than 0.05; beta = 0.14). During the late phase, the maximum decrease in FEV1 was 26.9% +/- 11.9% after placebo and 25.3% +/- 10.3% after gallopamil administration (p greater than 0.05; beta = 0.21). Airway reactivity to histamine 24 hours after allergen challenge could not be measured in three subjects after gallopamil administration and in one subject after placebo administration because of persistent bronchospasm. In contrast, basal responsiveness to histamine in the absence of allergen was modestly decreased by gallopamil. Since gallopamil is one of the most potent calcium channel blockers when it is administered by the inhaled route, it is unlikely that this group of drugs will be clinically useful for allergic asthma.

Administration, Inhalation↗
PubMed1992

Relative amount of albuterol delivered to lung receptors from a metered-dose inhaler and nebulizer solution. Bioassay by histamine bronchoprovocation.

The results of previous studies comparing bronchodilatation from beta agonists administered by metered-dose inhaler (MDI) and nebulizer solution have been conflicting. We therefore evaluated a range of albuterol doses administered by these two methods, using histamine bronchoprovocation as a bioassay for the amount of drug reaching the beta 2 receptors in the lung. Twelve stable asthmatic volunteers received, in a double-blind, randomized, crossover design on different days, placebo or one, two, four, or six puffs from an MDI attached to an InspirEase device (90 micrograms per puff) or 0.625, 1.25, 2.5, or 5.0 mg of solution delivered in 2 ml of buffered saline through a Hudson Updraft II nebulizer. The histamine concentration required to decrease FEV1 by 20 percent (PC20) was measured 1 h before and 30 min after administration of each treatment and expressed as the increase in PC20 from baseline. The dose-response curves for change in PC20 indicated that the higher doses of the nebulizer solution delivered more drug to beta 2 receptors in the lung than the lower doses from the MDI. For example, the geometric mean increase in PC20 was 1.1 +/- 1.6 (SD) after placebo, 7.5 +/- 2.7 after two puffs from the MDI, and 20.0 +/- 2.1 after 2.5 mg of nebulizer solution (p less than 0.05). Using this bioassay method and administration technique, we estimated that ten puffs from the MDI (0.9 mg) would deliver approximately the same amount of albuterol to lung receptors as 2.5 mg of the nebulizer solution. Taking into account previously published reports and the results of the present study, we conclude that differences in dose, administration technique, nebulizer system efficiency, and severity of airway obstruction can alter the amount of drug reaching the beta 2 receptors in the lungs and, thus, the clinical response.

Adult↗
PubMed1992

Evaluation of a generic albuterol metered-dose inhaler: importance of priming the MDI.

Since the patent on albuterol metered-dose inhalers (MDI) expired in 1989, several manufacturers have developed generic products. In order to determine whether one generic albuterol MDI is equivalent to a reference product (Ventolin MDI), we compared the relative efficacy of two puffs (180 micrograms) of each inhaler in 17 intermittent or mild chronic adult asthmatics (FEV1 48% to 77% predicted) in a randomized, single-blind, crossover manner. The test dose was the first two puffs out of each canister. Pulmonary function was measured before each test dose and at frequent intervals over eight hours. Baseline FEV1 values on both study days were within 20%. The mean +/- SD peak effect was 80.5 +/- 15.5% of maximum achievable improvement in FEV1 after the generic compared with 92.2 +/- 8.8% after Ventolin (P = .006). The area under the curve (AUC) for this same measurement during the first four hours was 242 +/- 75%.hr-1 after the generic compared with 297 +/- 40%.hr-1 after Ventolin, a mean difference of 19% (P = .002). The study was then repeated with the MDI primed prior to the test dose (ie, two puffs were first discharged into a waste basket) in subjects willing to return for re-study (n = 11). There was no significant difference in AUC in the second study: 215 +/- 77%.hr-1 after generic and 228 +/- 82%.hr-1 after Ventolin (P = .65); however, there was only a 35% chance of detecting a 20% difference in AUC with this sample size. These data indicate that, without priming, an MDI may deliver less drug, and thereby less therapeutic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗