The pharmacodynamic and pharmacokinetic interaction between single doses of flecainide acetate and verapamil: effects on cardiac function and drug clearance.

Flecainide and verapamil are antiarrhythmic agents that may be used in combination. We have examined their pharmacodynamic interaction by M-mode echocardiography and electrocardiography in eight normal male volunteers (24 +/- 1.8 years of age). Flecainide decreased the left ventricular ejection fraction (LVEF) (-4.4 +/- 1.2%, p less than 0.008), but verapamil did not. Neither drug affected cardiac output or vascular resistance. Both drugs increased the PR interval (12 +/- 4 msec, p less than 0.01 for flecainide; 12 +/- 5, p less than 0.04 for verapamil). Flecainide, but not verapamil, increased the QTc interval (23 +/- 8 msec, p less than 0.02). Both drugs also increased the systolic time interval ratio (PEPc/LVETc) (0.074 +/- 0.012, p less than 0.0004 for flecainide; 0.029 +/- 0.008, p less than 0.007 for verapamil). The combination of flecainide and verapamil had additive effects on myocardial contractility and on atrioventricular conduction. Verapamil slightly decreased the plasma clearance of flecainide (7.78 +/- 0.60 ml/kg/min for flecainide alone, 7.34 +/- 0.48 ml/kg/min for flecainide and verapamil together, p less than 0.05). On the other hand, flecainide had no effect on the plasma clearance of verapamil, which suggests that there was little interaction between the two drugs on their pharmacokinetic parameters.

Linkage analysis of a large Swedish kindred provides further support for a susceptibility locus for schizophrenia on chromosome 6p23.

Several reports have indicated genetic linkage between markers on the short arm of chromosome 6 and schizophrenia. However, significant threshold levels were not always achieved, and the chromosomal regions identified are large and different in different families. One way to decrease the problem of heterogeneity is to study a single extended pedigree. Here we report the analysis of a very large, previously undescribed pedigree from northern Sweden that includes 31 affected individuals. We typed 16 markers spanning 40 cM on the short arm of chromosome 6. Linkage analysis was performed only with the affected individuals. Suggestive lod scores (maximum 2.6) were obtained with markers on chromosome 6p23 in a single branch of the large pedigree indicating possible heterogeneity inside the family. A haplotype comprising markers from D6S309 to D6S1578 was found to segregate with the disease. This chromosomal region is included within a segment proposed to contain a susceptibility gene for schizophrenia by many other investigators. Our results thus give further support for a possible localization of a susceptibility locus for schizophrenia in 6p23 and help to narrow the candidate chromosomal region to the segment included between markers D6S309 and D6S1578.

Reduced risk of NSAID gastropathy (GI mucosal toxicity) with nonacetylated salicylate (salsalate): an endoscopic study.

This randomized, investigator-blinded, parallel group endoscopic study evaluated the effects of salsalate and naproxen on the gastroduodenal mucosa over a 3-month period in patients with RA. Using therapeutic doses of the drugs, 8 of 21 patients (38%) in the naproxen group had endoscopically shown active ulcers (seven patients) or diffuse erosions (one patient), whereas none of the 18 patients treated with salsalate (0%) had such lesions (P = .003). Five of the eight naproxen-treated patients with evidence of GI damage were asymptomatic at the time of endoscopic verification of their lesions. The most significant disadvantage of salsalate was its higher incidence of otologic problems accounting for six of the nine discontinuations with salsalate. However, the findings of this study suggest that patients receiving salsalate are at lower risk for developing significant gastropathy than those treated with naproxen. The relative benefit-to-risk ratio of salsalate indicates that this drug should be considered as a significant alternative NSAID therapy.

Does the acetyl group of aspirin contribute to the antiinflammatory efficacy of salicylic acid in the treatment of rheumatoid arthritis?

In a multicenter, double-blind, parallel-group study, 233 patients with classical or definite RA who demonstrated disease flare during a prestudy washout period were randomized to 12 weeks of treatment with either the nonacetylated salicylate, salsalate (salicylsalicylic acid), or aspirin. Of the 150 patients who completed the study, 83 received salsalate and 67 were treated with aspirin. Doses of the two drugs were calculated to provide equal amounts of bioavailable salicylic acid. The efficacy of salsalate and aspirin, as measured by all the usual variables, was equivalent but aspirin-treated patients had a higher incidence of severe gastrointestinal problems. Thus, this study demonstrated that the acetyl group of aspirin does not enhance the anti-inflammatory efficacy of salicylic acid in RA.

Cumulative dose-response study of non-CFC propellant HFA 134a salbutamol sulfate metered-dose inhaler in patients with asthma.

STUDY OBJECTIVE: This study compares the safety and efficacy of HFA 134a salbutamol sulfate (Airomir in the 3M CFC-free system [3M Pharmaceuticals]) and CFC 11/12 salbutamol (Ventolin [Allen & Hanburys]) in a cumulative dose-response (1, 1, 2, 4, 8 inhalations at 30-min intervals) study in asthmatic patients. DESIGN: Randomized, single-blind, two-period cross-over study. PARTICIPANTS: Twenty-four stable mild to moderate asthmatics. MEASUREMENTS AND RESULTS: At all cumulative inhalations, the changes in FEV1 (absolute, percent, and percent predicted) and FVC were equivalent. There was also no significant difference in heart rate, serum potassium level, BP, 12-lead ECG, Holter monitor recordings, or adverse events. Both HFA 134a salbutamol sulfate and CFC 11/12 salbutamol displayed a significant dose-response for FEV1, FEF25-75%, FVC, serum potassium, heart rate, and systolic BP. CONCLUSIONS: HFA 134a salbutamol sulfate and CFC 11/12 salbutamol produced clinically and statistically similar airway responses and side effects. These results indicate that HFA 134a salbutamol sulfate would be a safe and effective substitute for CFC 11/12 salbutamol.

Safety of long-term treatment with HFA albuterol.

BACKGROUND: Chlorofluorocarbons (CFCs) used as propellants in metered-dose inhalers deplete stratospheric ozone, which results in serious public health concerns. Albuterol has been reformulated in the non-ozone-depleting propellant, hydrofluoroalkane-134a (HFA albuterol). OBJECTIVES: The primary objective was to compare the safety of HFA albuterol to an albuterol product formulated in chlorofluorocarbon propellants (CFC albuterol) during 1 year of treatment in asthmatics. Bronchodilator efficacy of the two products was assessed as a secondary objective. METHODS: The results from two open-label, parallel-group trials of similar design in asthmatics requiring short-acting beta-agonists for symptom control were combined. Patients took two puffs bid of either HFA albuterol or CFC albuterol for 1 year. Additional puffs of study drug were allowed as needed to control asthma symptoms. Adverse events were recorded at clinic visits. Patients self-administered study drug at quarterly visits and underwent serial spirometry during a 6-h period postdose. Bronchodilator efficacy variables, based on FEV1 response to study drug, were proportion of responders, time to onset of effect, peak percent change, time to peak effect, duration of effect, and area under the curve. Differences between products and changes over time in efficacy variables were assessed using an analysis of variance model. Regression analyses with FEV1 as a covariate were performed post-hoc to analyze changes in bronchodilator efficacy over time. RESULTS: Demographic and baseline characteristics were similar for patients receiving HFA albuterol (n = 337) and CFC albuterol (n = 132). Total reported adverse events were similar for the two treatments. Differences in only four individual adverse events were noted: the HFA albuterol group reported more gastroenteritis and dizziness; the CFC albuterol group reported more epistaxis and expectoration. Adverse events attributed to study drug use were infrequent. No serious adverse events were related to study drug use. Predose FEV1 at quarterly visits increased to a small extent in both groups from month 0 to month 12. The bronchodilator efficacy of HFA albuterol was comparable to that of CFC albuterol at the quarterly visits, but decreased from baseline for both products over the 12 months of treatment. Use of inhaled corticosteroids, nasal corticosteroids, or theophylline did not explain the increase in predose FEV1 over time and did not protect patients from developing reduced bronchodilator efficacy by month 12. The change in predose FEV1 did not entirely account for the reduced bronchodilator efficacy over time. CONCLUSIONS: HFA albuterol has a safety profile similar to that of CFC albuterol during chronic, scheduled use, and both drugs are well tolerated. HFA albuterol and CFC albuterol provided comparable bronchodilator efficacy, but bronchodilator efficacy decreased for both products with 1 year of use.

Proventil HFA and ventolin have similar safety profiles during regular use.

OBJECTIVE: As a secondary objective to a long-term study evaluating the bronchodilator effectiveness of Proventil HFA (albuterol), to assess the safety of Proventil HFA, Ventolin, and hydrofluoroalkane 134a (HFA-134a) placebo over 12 weeks of regular dosing. DESIGN: Randomized, double-blind, double-dummy parallel group, placebo-controlled, multicenter trial of asthmatics requiring inhaled beta-adrenergic bronchodilators for symptom control. INTERVENTIONS: Treatment with Proventil HFA, Ventolin, or HFA-134a placebo, qid, for 12 weeks. MEASUREMENTS: Adverse events were reviewed at biweekly clinic visits. Between clinic visits, patients recorded morning and evening peak expiratory flow (PEF), asthma symptom and nighttime asthma sleep disturbance scores, and use of rescue beta-adrenergic bronchodilator on diary cards daily. Investigators provided a global assessment of asthma control at weeks 0, 4, 8, and 12. Vital signs were recorded over 6 h after dosing with study drug at weeks 0, 4, 8, and 12. Standard laboratory tests, CBC count, serum chemistries, and urinalysis were obtained at study start and end. RESULTS: Adverse event reporting rates were similar for the three treatment groups. The morning PEF tended to be lower for the Proventil HFA and Ventolin groups than the HFA-134a placebo group, but the evening PEF tended to be higher for the active treatment groups. Daytime asthma symptom scores tended to be lower (better) with active treatment than placebo, but nighttime asthma sleep disturbance scores were similar for all three treatment groups. Use of Ventolin Rotacaps as rescue medication was significantly greater for the HFA-134a placebo group than the Proventil HFA and Ventolin groups. Diary card data did not change within groups over time. Investigator global assessments of asthma scores clustered between fair and good for all three treatment groups throughout the study. Changes in heart rate and BP were small after dosing with study drug and tended to be similar for the active treatments and HFA-134a placebo groups. No clinically meaningful changes in results of standard laboratory tests were found in any treatment group during this study. CONCLUSIONS: Proventil HFA had a similar safety profile as Ventolin during regular use. A dosage of 16 puffs per day of propellant HFA-134a was well tolerated by asthmatics. Regular use of either Proventil HFA or Ventolin did not cause asthma control to deteriorate.

Proventil HFA provides bronchodilation comparable to ventolin over 12 weeks of regular use in asthmatics.

OBJECTIVE: To compare the bronchodilator effectiveness of albuterol reformulated in the chlorofluorocarbon-free propellant hydrofluoroalkane (HFA)134a (Proventil HFA) to that of Ventolin and HFA placebo over 12 weeks of regular dosing. DESIGN: Randomized, double-blind, double-dummy, parallel group, placebo-controlled, multi-center trial of asthmatics requiring inhaled beta-adrenergic bronchodilators for symptom control. INTERVENTIONS: Treatment qid with Proventil HFA, Ventolin, or HFA-134a placebo for 12 weeks. MEASUREMENTS: At weeks 0, 4, 8, and 12, spirometry was performed predose and serially over 6 h after dosing with study drug. Bronchodilator efficacy variables, based on FEV1 response to study drug, were proportion of responders, time to onset of effect, peak percent change, time to peak effect, duration of effect, and area under the curve (AUC). RESULTS: Demographic and baseline characteristics were similar for patients randomized to Proventil HFA (193), Ventolin (186), and HFA-134a placebo (186). No significant differences were found between the Proventil HFA and Ventolin treatment groups for any FEV1 efficacy variable, either predose or during 6 h of serial spirometry, at weeks 0, 4, 8, and 12. For all efficacy variables, except time to onset of effect, the Proventil HFA and Ventolin results were significantly greater than placebo. Time to onset of effect for the HFA-134a placebo group is misleading; only 13 patients (7%) were found to be responders in the intent-to-treat database. These efficacy results were found to be consistent across subgroup analyses of inhaled and nasal corticosteroid use, age (18 to 35 and 36 to 66 years), sex, race, weight (<60, 60 to 100, and >100 kg), and baseline FEV1 (< or =55% and >55% predicted). The peak FEV1 effect, duration of FEV1 effect, and AUC for FEV1 were all significantly smaller at weeks 4, 8, and 12 than week 0 for both the Proventil HFA and Ventolin treatment groups. CONCLUSIONS: Proventil HFA provided bronchodilation comparable to Ventolin and superior effects to HFA-134a placebo over 12 weeks of regular dosing. There was a diminution in bronchodilator response to both Proventil HFA and Ventolin after 4 weeks of use.

Anticipation in Swedish families with schizophrenia.

Nineteen parent-offspring pairs obtained from 14 two-generation families with available medical records and diagnosis of schizophrenia were studied to compare the ages of onset of the parent generation with those of the offspring generation. The mean age of onset for the parent generation was 37.3 +/- 6.0 years and for the offspring generation was 20.8 +/- 4.4. The mean difference was thus 16.5 +/- 6.2, suggesting the occurrence of anticipation in schizophrenia (p < 0.001). Although some ascertainment biases (like reduced fertility in early-onset parents or early detection of symptoms in offsprings of affected parents) may partially contribute to the occurrence of anticipation, this study replicates recent reports of anticipation in several neuropsychiatric disorders, some of which have been shown to be associated with unstable expansions of trinucleotide repeats in the genomic DNA.

Comparative pharmacokinetics of morning and evening doses of once-a-day theophylline capsules.

The objective of this study was to determine if the theophylline diurnal variation that has been observed primarily between morning and evening doses of twice-a-day products could be overcome by a once-a-day formulation. Eighteen healthy, nonsmoking, adult male subjects were given 900-mg theophylline doses as three 300-mg once-a-day theophylline capsules in the morning or evening for 5 days in a single-blind fashion. Matching placebo capsules were administered midway between each dose of active drug. Predose theophylline serum levels on day 3-6 were statistically equivalent within each treatment, indicating that approximate steady-state conditions were achieved by day 3. Mean serum level profiles over the 24-h interval following the active dose on day 5 were almost superimposable for the morning and evening treatments. All pharmacokinetic parameters were equivalent between the treatments, except for the time to peak serum level (Tmax), which was significantly shorter for the morning dose. Given the flatness of the serum level curves for both treatments, the Tmax difference was judged to be clinically unimportant. A small peak-trough level fluctuation of about 50% was seen with each treatment. We conclude that by designing a dose form in which drug release was the rate-limiting step in drug absorption, the diurnal variation commonly associated with theophylline formulations may be eliminated.

Pharmacokinetic differences between chlorofluorocarbon and chlorofluorocarbon-free metered dose inhalers of beclomethasone dipropionate in adult asthmatics.

We have compared the serum pharmacokinetics of the metabolites of beclomethasone dipropionate after inhalation from chlorofluorocarbon (CFC) and hydrofluoroalkane HFA-134a (HFA) formulations in asthmatic patients. Twenty-three patients completed this open-label, randomized, single-dose, three-period crossover study. Each patient received in separate periods 200 microg or 400 microg HFA-beclomethasone dipropionate, or 400 microg CFC-beclomethasone dipropionate. Venous blood samples were collected over 24 h for the determination of beclomethasone esters and beclomethasone in the serum. Significant differences in pharmacokinetics following HFA- and CFC-beclomethasone dipropionate were observed. Following a 400 microg beclomethasone dipropionate dose, the HFA formulation gave mean maximum concentrations (Cmax) and area under the curve (AUC) values of beclomethasone esters of 1153 pg mL(-1) and 4328 pg h mL(-1), respectively, and beclomethasone Cmax and AUC values of 69 pg mL(-1) and 682 pg h mL(-1), respectively. These values were approximately 2-3-fold those seen with the CFC formulation (beclomethasone esters Cmax and AUC of 380 pg mL(-1) and 1764 pg h mL(-1), respectively; beclomethasone Cmax and AUC of 41 pg ml(-1) and 366 pg h mL(-1), respectively). Beclomethasone esters, the major component of beclomethasone dipropionate in the serum, peaked significantly earlier for the HFA formulation (0.8 h) than for the CFC formulation (2 h). Tests for dose proportionality of beclomethasone esters pharmacokinetics following HFA-beclomethasone dipropionate showed that the two hydrofluoroalkane strengths were proportional. The more rapid and greater efficiency of systemic drug delivery of the HFA formulation compared with the CFC formulation can be explained if most of each inhalation from CFC-beclomethasone dipropionate is swallowed and absorbed orally, whereas most of each inhalation from HFA-beclomethasone dipropionate is absorbed through the lungs. There is a need for comprehensive dose-response efficacy trials, with the use of the steep portion of the dose-response relationship, to evaluate the significance of these pharmacokinetic differences.

Twenty-eight-day double-blind safety study of an HFA-134a inhalation aerosol system in healthy subjects.

A 28-day double-blind parallel group study has been conducted to compare the safety and tolerability of HFA-134a, a chlorofluorocarbon-free propellant in a pressurized metered-dose inhaler (MDI A), with a chlorofluorocarbon propellant (MDI C). Sixteen subjects were randomly assigned to receive one of the two MDIs, either four inhalations four times per day for 14 days or eight inhalations four times a day for 14 days, and were then crossed over to the alternative exposure regime with the same propellant for the next 14-day period. No clinically significant changes occurred in blood pressure, heart rate, electrocardiograms, pulmonary function (FEV1, FVC, FEF25-75%), haematology or serum chemistry. One subject in the MDI A group had elevated eosinophil counts throughout the study; there were no other remarkable clinical laboratory data. Fifty six adverse events were related to the study propellants; 34 of these occurred in the MDI C group and 22 in the MDI A group. For each adverse event no statistically significant differences were detected between propellant systems or between exposure levels. The most frequent adverse event was headache, which was reported by four subjects with each propellant system. Blood samples for HFA-134a in the MDI A group were collected on day 28 to measure systemic absorption. Blood levels of HFA-134a were detected in all subjects given this propellant within 1 min post-exposure, and these levels decreased to one-tenth of the original value by 18 min after the start of exposure. The safety and tolerability of an HFA-134a chlorofluorocarbon-free system was demonstrated over 28 days of exposure in healthy subjects. These negative results are clinically important because they indicate it will be safe to proceed with the study of this chlorofluorocarbon-free system in asthmatic patients.

A novel breath actuated device (Autohaler) consistently actuates during the early phase of inspiration.

OBJECTIVE: To establish and quantify the point during inspiration that the Autohaler (AH) inhalation system releases a metered dose of aerosol (placebo). The second objective was to determine if the Autohaler system actuates consistently, regardless of the canister life. DESIGN: Double-blind, randomized, two-period crossover, one-day trial. SETTING: Community based allergy and asthma clinic. PARTICIPANTS: Twelve patients with mild to moderate asthma. RESULTS: Mean verbal training time for the AH which included the patient demonstrating their ability to correctly use the AH was approximately 6 minutes. The mean time for actuation for the AH early in its canister life ("new canister") was 195 msec compared to 205 msec for the AH late in its canister life ("old canister") (p = 0.589). This represented the early part of inspiration as patients had a mean inspiratory duration of 2231 msec for the "new" AH and 2343 msec for the "old" AH. The mean percentage of inspiration time required to actuate the "new" AH was 8.92% compared to 8.82% for the "old" AH. Patients rated the system as easier to much easier to use compared with their current standard press and breathe inhaler. CONCLUSIONS: The AH consistently actuates early during inspiration, which is considered the optimal time for drug delivery, regardless of the canister life.

An endoscopic comparison of the gastroduodenal injury seen with salsalate and naproxen.

Forty endoscopically normal healthy subjects were randomized to receive either BID salsalate (3500 mg/day) or BID naproxen (750 mg/day) for 14 days followed by repeat endoscopic examination. Gastroduodenal lesions were found in 55% (11/20) of the subjects taking naproxen, and 10% (2/20) of those taking salsalate (p = 0.002). Twenty-five percent (5/20) of the subjects taking naproxen and none of the subjects taking salsalate were noted to have severe gastric injury (p = 0.003). There was no difference between the 2 groups in subjective gastrointestinal system adverse experiences. Overall, 95% (19/20) of subjects taking salsalate reported at least 1 adverse experience compared with 60% (12/20) of those taking naproxen (p = 0.02). This was due primarily to the higher number of subjects taking salsalate reporting reversible tinnitus or hearing loss. There was no significant treatment difference in adverse experiences reported for any other organ system. The results of our study support previous observations in patients with rheumatoid arthritis that salsalate produces less gastroduodenal mucosal toxicity than the widely used antiinflammatory agent, naproxen.

Comparable bronchodilation with hydrofluoroalkane-134a (HFA) albuterol and chlorofluorocarbons-11/12 (CFC) albuterol in children with asthma.

This was an open-label, parallel group, randomized, age-stratified, multicenter study designed to compare the safety and efficacy of regular use of albuterol formulated in hydrofluoroalkane-134a (HFA albuterol) and albuterol formulated in chlorofluorocarbons-11/12 (CFC albuterol) in children with asthma. Children age 4-11 years using a short-acting inhaled beta2-agonist for 6 months to manage stable asthma, and with a prestudy forced expiratory volume in 1 sec (FEV1) of >50% predicted after withholding short-acting inhaled beta2-agonists for at least 6 hr, an increase in FEV1 > or = 12% within 30 min after two puffs of CFC albuterol, and the capability to comply with medication withholding requirements were eligible for study entry. After screening evaluation, patients entered a minimum 7-day run-in period. On study day 1 spirometry and a baseline 12-lead electrocardiogram (ECG) were performed, pulse and blood pressure were measured, and patients self-administered two puffs of their randomized study drug, either HFA albuterol or CFC albuterol. Serial spirometry was performed over 6 hr after study drug dosing. Pulse and blood pressure were measured just prior to each spirometry and a 12-lead ECG was performed at 60 min postdose. Patients took two puffs of their study drug four times a day for 4 weeks. At study week 4, study day 1 procedures were repeated. Patients maintained a daily diary of morning (A.M.) and evening (P.M.) peak expiratory flow (PEF), daytime asthma symptom scores, nighttime asthma sleep disturbance scores, and study drug use. Demographics and baseline characteristics of the 63 patients randomized to HFA albuterol (33) and CFC albuterol (30) were similar. No significant differences were found between the HFA albuterol and CFC albuterol treatment groups for any of the primary or secondary FEV1 efficacy variables either at study day 1 or study week 4. No significant differences were noted between treatment groups for A.M. and P.M. PEF, individual asthma symptom scores, nighttime asthma sleep disturbance scores, and rescue study drug use over the 4-week study. No significant differences were found between the two treatment groups for change from predose in heart rate, systolic and diastolic blood pressure, and 12-lead ECG intervals at either study day 1 or study week 4. Adverse event reporting was similar for the two treatment groups. In this study, with regular use of HFA albuterol in children with asthma, there was a similar safety profile and comparable bronchodilator efficacy as with CFC albuterol.

Assessing differential drug effect.

The regression effect gives a misleading impression of the relationship between drug or treatment effect and baseline measurement. We propose a method of adjusting for the regression effect; we also suggest a corresponding test for the differential drug effect. The likelihood ratio test for no differential drug effect is equivalent to a test for equality of variances, suggested by Pitman (1939, Biometrika 31, 9-12) and Morgan (1939, Biometrika 31, 13-19). The proposed adjustment and test are applied to an example of blood pressure data.

Evaluation of conventional press-and-breathe metered-dose inhaler technique in 501 patients.

Conventional press-and-breathe metered dose inhalers (MDIs) are widely prescribed but are often difficult for many patients to properly use. A total of 501 patients from different medical specialties were enrolled in this study, which evaluated how the patients used their MDIs. Using a conservative method (minimum number of errors) of determining errors, we found that 388 (77.5%) of the patients made at least one error when demonstrating how they use their MDI for two observers. Using a liberal (maximum number of errors) method of analysis, we found that 447 (89.2%) of the patients made at least one error. There was no difference in errors made stratified by patient gender, patient age, or the medical specialty that treated the patient's pulmonary disease. The two most common errors made by patients were failure to breathe out to functional residual capacity before actuation (225 by minimum method, 280 by maximum method) and not actuating the canister at the start of inhalation (207 by minimum method, 323 by maximum method). Of the patients with improper timing of actuation, the majority (121 patients by minimum method and 187 patients by maximum method) actuated the canister early. In this large patient sample, regardless of which medical specialty provided the treatment, the majority of the patients evaluated had less than optimal MDI technique. Routine assessment of MDI technique should be instituted as standard practice care.

Cumulative dose response study comparing HFA-134a albuterol sulfate and conventional CFC albuterol in patients with asthma.

BACKGROUND: As a result of the pending ban on chlorofluorocarbon production, the non-chlorofluorocarbon propellant 1,1,1,2-tetrafluoroethane (HFA-134a) is being evaluated as a replacement for CFCs in metered-dose inhalers. OBJECTIVES: This cumulative dose response study compared the safety and bronchodilator efficacy of 16 cumulative inhalations of albuterol sulfate in an HFA-134a, CFC-free propellant system (108 microg of albuterol sulfate, equivalent to 90 microg of albuterol base) with that of equivalent doses of albuterol in a conventional CFC propellant system. METHODS: Twenty-two patients with at least a 12-month history of stable asthma, who were currently taken an inhaled beta-adrenergic bronchodilator, and who had a FEV1 between 40% and 80% of predicted, were enrolled in this randomized, modified-blind, two-period crossover study. One, 1, 2, 4, and 8 inhalations of study drug were self-administered at 30-minute intervals, resulting in 16 cumulative inhalations. Pulmonary function and safety measures were assessed after each dosing interval. RESULTS: A significant dose response was found for HFA-134a albuterol sulfate and CFC albuterol with regard to changes in FEV1, serum potassium, heart rate, and blood pressure after 16 cumulative inhalations. No significant differences were demonstrated between HFA-134a albuterol sulfate and CFC albuterol for any FEV1 or safety parameter at any cumulative dose level. No clinically meaningful laboratory or physical examination abnormalities were found with administration of either HFA-134a albuterol sulfate or CFC albuterol. CONCLUSIONS: HFA-134a albuterol sulfate provides bronchodilation comparable to CFC albuterol and has a similar safety profile.

Proventil HFA prevents exercise-induced bronchoconstriction in children.

Short-acting inhaled beta2-agonists used just prior to exercise are an effective method for preventing exercise-induced bronchoconstriction (EIB) in children. This was a randomized, single-blind, placebo-controlled, four-period crossover study that compared the effectiveness of albuterol formulated in hydrofluoroalkane-134a (HFA) to albuterol formulated in chlorofluorocarbons (CFCs) and to placebo in protecting asthmatic children age 6-11 from EIB. Patients self-administered either HFA albuterol, two different CFC albuterol products, or placebo 30 min prior to exercise challenge. Spirometry was performed predose and 5, 10, 15, 30, 45, 60, 75, and 90 min after the exercise challenge was completed. The smallest percent change from the predose forced expiratory volume in 1 sec (FEV1) after exercise challenge was similar for the three active treatments, and each of the active treatments was significantly better than placebo. Each active treatment had significantly fewer patients unprotected from EIB (unprotected defined as having >20% fall in FEV1 after exercise challenge) than placebo. Changes in heart rate, blood pressure and electrocardiogram (ECG) intervals were similar for the three active treatments following exercise. HFA albuterol is as effective as albuterol products formulated in CFCs and more effective than placebo in protecting asthmatic children from EIB.