The efficacy of a new salbutamol metered-dose powder

Vol. 95 (2001) 949^953 The e⁄cacy of a new salbutamol metered-dose powder inhaler in comparison with two other inhaler devices O.-P. SEPPØLØ*, E. AALTOw, I. ANNILAz,T. HAKONEN}, E. LUKKARI-LAX}, T. JOUHIKAINEN}, M. M. NIEMINENz AND K. LIIPPO* * Department of Pulmonary, Diseases,Turku University Central Hospital, wDepartment of Pulmonary Diseases, HÌrmÌ Hospital zDepartment of pulmonary Diseases, Tampere University Hospital and }Clinical Research, Leiras Oy, Finland Abstract An open cross-over and randomized study was carried out in order to compare the e⁄cacy and safety of inhaled salbutamol delivered from a new 50 mg doseÿ1 metered-dose dry powder inhalerTaifuns, and a commercially available 50 mg doseÿ1 dry powder inhalerTurbuhalers, and a conventional100 mg doseÿ1 pressurized metered-dose inhaler with a spacer (pMDI+S).Twenty-one patients, aged 21^70 years, with stable asthma and with demonstrated reversibility upon inhalation of salbutamol were included in the study.On three separate study days, the patients received a total dose of 400 mg of salbutamol from the dry powder inhalers and a dose of 800 mg from the pMDI+S in a cumulative fashion:1,1, 2 and 4 doses at 30 min intervals.The per cent change in forced expiratory volume in1sec (FEV1), was used as the primary e⁄cacy variable. Salbutamol inhaled via theTaifuns produced greater bronchodilation than the other devices.The di¡erence in percent change in FEV1 between theTaifuns and the other devices was statistically signi¢cant at the two ¢rst dose levels, but diminished towards the higher doses when the plateau of the dose^response curve was reached.The estimated relative dose potency oftheTaifuns was approximately1?9- and 2?8-fold compared to theTurbuhalers and the pMDI+S, respectively.TheTaifuns caused a slight, butclinicallyinsigni¢cant, decreasein serum potassium concentration.There were no signi¢cantchangesinthe other safetyparameters (blood pressure, heartrate and electrocardiogram recordings) with any of the used devices. In conclusion, this study indicates that salbutamol inhaled via the Taifuns is more potentthan salbutamolinhaled from the other devices tested.In practise, a smaller total dose of salbutamol from theTaifuns is needed to produce a similar bronchodilatory response. All treatments were equally well tolerated.r 2001Harcourt Publishers Ltd doi:10.1053/rmed.2001.1189, available online at http://www.idealibrary.com on Keywords asthma; salbutamol; bronchodilatron; dry powder inhaler. INTRODUCTION Inhaled, short-acting, selective b2 -adrenoceptor agonists, such as salbutamol, have played an important role in the treatment of asthma and other conditions associated with reversible airway obstruction. Their rapid onset of action makes them the medication of choice for the treatment of acute asthma attacks and for the prophylaxis of exercise- and allergen-induced bronchoconstriction (1). The predominant formulation of inhaled medication has been the chloro£uorocarbon (CFC)-based Received 8 January 2001, accepted in revised form 13 July 2001 and published online 22 October 2001. Correspondence should be addressed to Dr O.P. SeppÌlÌ, Department of Pulmonary Diseases, Turku University Central Hospital, Paimion Sairaala, FIN-21540 PreitilÌ, Finland. pressurized metered-dose inhaler (pMDI), which was invented over 40 years ago and has remained practically unchanged since. In addition to the fact that CFC gases used in pMDIs deplete the ozone layer of our atmosphere (2), they may irritate the bronchial mucous membranes (3). Also, di⁄culties in co-ordinating the actuation of the pMDI and inhaling the drug (4) are frequently seen. These problems have led to the development of either alternative propellants or entirely di¡erent devices, metered dose powder inhalers (MDPI). With MDPIs all that described above can be avoided, and they are now generally considered as the devices of choice for future inhalation therapy of asthma. Recently, Leiras Oy has developed a new breathactuated MDPI, Taifuns (Fig. 1). It contains 200 doses of salbutamol (50 or 100 mg doseÿ1) with lactose carrier, provides a high respirable fraction (40^ 45% of the 950 delivered dose) and with a mass median aerodynamic diameter of 2?5^2?7 mm, and is e⁄cient in delivering the salbutamol dose into the lungs (5). In previous studies the Taifuns proved to be at least as e¡ective in causing bronchodilation (6) as one of the pMDIs with a spacer device (S), and better in o¡ering protection against methacholine-induced bronchoconstriction (7) than another conventional pMDI+S. The aim of this study was to compare the e⁄cacy and relative potency of cumulative doses of salbutamol inhaled from the Taifuns (50 mg doseÿ1) or via another MDPl (Turbuhalers) or a pMDI+S. RESPIRATORY MEDICINE TABLE 1. Summary of demographic characteristics of the recruited patients (n=21) Characteristic Mean7SD Range Age (years) Weight (kg) Height (cm) FEV1 (l)* FEV1 of predicted (%) Reversibility in FEV1 after salbutamol (%)* 50?4713?4 81?2717?3 17079 2?1370?59 62?5713?2 23?3710?4 21^70 60^136 156^191 1?05^3?36 37^96 15?1^51?2 *Measured atthe screening visit. METHODS Design This was a randomized, open, cross-over, cumulative dose study, which was carried out in three clinics of pulmonary diseases in Finland. Each subject attended the laboratory three times after the screening visit. The sessions were at least 24 h apart, and the subjects completed the study within 2 weeks from the screening visit. Subjects Twenty-one outpatients (nine males) with chronic asthma, and a reversibility of forced expiratory volume in 1sec (FEV1) of at least 15% measured 20 min after inhalation of 200 mg of salbutamol from a Ventolines pMDI connected to a Volumatics spacer were enrolled. The patients ful¢lled the American Thoracic Society criteria for asthma.The detailed demographic characteristics of the enrolled patients are listed in Table 1. All patients were of Caucasian origin. Nine of them were ex-smokers, the others had never smoked. Seventeen of the patients used inhaled glucocorticosteroids,13 inhaled short-acting and six long-acting b2 -adrenoceptor agonists. One patient used a combination product of an inhaled anticholinergic and b2 -adrenoceptor agonist.Two patients had inhaled chromones, and one was on antihistamine medication due to allergic rhinitis. Additionally, six patients were on regular medication for other than respiratory or allergic conditions; one patient took an oestrogen supplement for menopausal symptoms, two patients zopiclone for insomnia, two paracetamol for musculoskeletal pains, one thyroxin for hypothyreosis, and one patient isosorbide-5-mononitrate and diltiazem for coronary artery disease. Further, concomitant medication was withheld as follows: inhaled short-acting b2 -adrenoceptor agonists for 12 h, oral and inhaled long-acting b2 -adrenoceptor agonists for 48 h, inhaled anti-cholinergics for 24 h, oral anti-cholinergics for 7 days, and theophylline and its derivatives for 72 h, prior to each study visit. Concomitant medication with nasal, inhaled or oral glucocorticosteroids, or inhaled nedocromil or sodium cromoglycate, with a constant dose for at least 1 month prior to and during the study was allowed. The study was performed in accordance with the principles stated in the Declaration of Helsinki and the principles of Good Clinical Practice adopted by the European Community. The Finnish National Agency for Medicines was noti¢ed of the study, and the study was approved by the ethics committees of each hospital. All subjects gave their signed informed consent before they were enrolled in the study. Instruments and drugs Pulmonary function was measured with Vitalograph Compact IIs spirometers (Vitalograph Ltd., Buckingham, U.K.) calibrated prior to the study. The calibration was checked daily before any study measurements. The equipment was used only for the present study. The reversibility test was performed with an inhalation of 200 mg of salbutamol from Ventolines pMDI connected to a Volumatics spacer (both from GlaxoWellcome, Uxbridge, U.K.). The studied inhalers were Taifuns (Leiras Oy, Turku, Finland) giving 50 mg of salbutamol per dose with lactose carrier, salbutamol 50 mg doseÿ1 Turbuhalers (Astra AB, SošdertaŒlje, Sweden), and 100 mg doseÿ1 Ventolinesþ Volumatics (pMDI+S). In order to optimize the function of the devices, inhalation techniques recommended by the manufacturers were followed. When using the Taifuns the patients after having loaded the device exhaled normally to functional capacity (FRC) and then took a normal, slow tidal volume inhalation through the device. With theTurbuhalers the procedure was similar, except that the inhalation through the device was deep and forceful. When the pMDIþS was used, after shaking the canister the patients exhaled to FRC, placed the mouthpiece ¢rmly between their lips and actuated the device, and after a wait of 2^ 4 sec took a slow and deep inhalation. In order to maximize lung deposition all inhalation procedures were followed by a breath holding period of 10 sec. RELATIVE EFFICACYOFA NEW SALBUTAMOL DRY POWDER INHALER 951 Study procedure RESULTS The patients were randomized for the sequence of the three inhalers, and inhaled salbutamol on three separate days. On each study visit the baseline pulmonary function was established by having the patients do repeated spirometric e¡orts at intervals of 1min until obtaining three FEV1 values from consecutive measurements, of which at least two were within a range of 0?1^l. The better of these two values was recorded as the baseline FEV1 which was required to be within 712% from the baseline values of all other study days. All the baseline measurements were performed at the same time between 07?00 and 11? 00 hours. Immediately after them, cumulative doses of salbutamol were inhaled at 30 min intervals as follows: from the Taifuns and Turbuhalers 1+1+2+4 inhalations with cumulative doses of 50, 100, 200 and 400 mg of salbutamol; from the pMDI+S 1+1+2+4 inhalations with doses of 100, 200, 400 and 800 mg of salbutamol. Pulmonary function was measured 25 min after each drug dose, and the FEV1 from the best technically valid spirometric e¡ort of three was recorded. As safety precautions, every patient’s electrocardiogram (ECG), blood pressure (BP) and heart rate (HR) were recorded during the study. ECG was recorded before and after the study procedures. BP and HR were recorded before the ¢rst drug inhalation and 20 min after each dose. Also blood samples for analysing serum potassium (S-K) levels were collected before the ¢rst, and 30 min after the last, drug inhalation. All but two of the recruited patients completed the study according to the protocol. Both discontinuations were due to exacerbation of asthma. The mean (SD) baseline FEV1 values of the Taifuns, Turbuhalers and pMDI+S periods were 2?12 (0?59) l, 2?11 (0?62) l and 2?17 (0?58) l, respectively. The cumulative salbutamol doses caused bronchodilation increasing dose by dose, which at the ¢rst two doses was most prominent with the Taifuns, followed by the Turbuhalers and then the pMDI+S (Fig. 2). At the ¢rst two dose steps theTaifuns di¡ered signi¢cantly from the other devices, the Turbuhalers (P = 0?037 for the ¢rst and P = 0?007 for the second dose) and the pMDI+S (P = 0?019 for the ¢rst and P = 0?028 for the second dose) (Table 2). At higher dose levels (200 and 400 mg for the Taifuns and the Turbuhalers, 400 and 800 mg for the pMDI+S) the di¡erence between the devices diminished, being no longer signi¢cant, but the order of e⁄cacy remained (Fig. 2, Table 2). The estimated relative dose potency (95% CI) of the Taifuns was 1?9 (1?4^2?6) and 2?8 (2?1^3?8) when compared to the Turbuhalers and pMDI+S, respectively. The relative potency of the Data analysis The results are presented as means and standard deviations (SD), unless otherwise indicated. All analyses were based on the intent-to-treat population. Per cent change in FEV1 from the baseline was used as the primary e⁄cacy variable. A one-sided 95% con¢dence interval (95% CI), corresponding to a two-sided 90% CI (90% CI), based on the least square of means was calculated to test the non-inferiority of the Taifuns in comparison with the other devices. If Taifuns was detected to be at least as e¡ective as the other devices, analysis of variance (ANOVA) with a 3  3 cross-over design or corresponding non-parametric method was performed. ANOVA was performed also for numerical safety parameters. A P-value of less than 0?05 was considered statistically signi¢cant. Also, to support the results of the primary e⁄cacy parameter, the relative dose potency of the devices was calculated by estimating the parallel shift of the dose-response curves by applying a linear model: e¡ect = subject+ device+period+log-dose. A normal two-sided 95% con¢dence interval (95% CI) was calculated for this parameter. FIG. 1. TheTaifuns inhaler. FIG. 2. The increase in FEV1 after each salbutamol dose. Taifuns (-^-),Turbuhalers (-&), pMDI+S(*). 952 RESPIRATORY MEDICINE TABLE 2. The di¡erence in per cent changes between theTaifuns and other studied devices presented as % units and twosided 90% con¢dence intervals in brackets (90% CI) Dose from theTaifuns 50 mg s Turbuhaler 50 mg 100 mg 200 mg 400 mg PMDI+S 100 mg 200 mg 400 mg 800 mg 100 mg 200 mg 400 mg 5? 2 (1.1^9?4) 4? 9 (1?9^7?9) 1?5 (ÿ1?8 ^ 4? 8) 1?5 (ÿ2?7^5?6) 5?9 (1?7^10?0) 4?0 (1?0 ^ 6?9) Turbuhalers was estimated to be 1?5 (1?1^2?0) of that of the pMDI+S. All S-K concentrations measured during the study were within the normal range (3?5^5?1mmol ÿ1). The mean (SD) baseline S-K levels were 4?22 (0?19), 4?12 (0?28) and 4?25 (0?24) mmol l ÿ1 at the Taifuns, Turbuhalers and pMDI+S periods, respectively. After the salbutamol inhalations the corresponding values were 4?12 (0?22), 4?21 (0?22) and 4?15 (0?30) mmol lÿ1. The di¡erence between the Taifuns and the Turbuhalers was statistically signi¢cant, ÿ0?19 (95% CI ÿ0?33 to 0?05). TheTaifuns and the pMDI+S did not di¡er in this respect from each other; the di¡erence in S-Kvalues was 0?01 (95% CI ÿ0?15 to 0?12). The baseline BP, HR or ECG did not di¡er between medications and there were no signi¢cant changes in these parameters during the di¡erent treatments. There were 10 reported AEs, altogether, in ¢ve patients during the study: two after the Taifuns, three after theTurbuhalers and four after the pMDI+S period. Of these only four AEs in two patients were probably drug-related: one event of tremor after each treatment and one report of dizziness after Turbuhalers treatment. DISCUSSION The development of new inhalation devices raises the question of their relative e⁄cacy. This investigation was carried out in order to compare the e⁄cacy of a new salbutamol MDPI, Taifuns, with that of another MDPI and a conventional pMDI with a spacer containing the same active drug substance.When comparing di¡erent inhalers, it would have been preferable to employ a doubleblind and double-dummy technique. However, for reasons of simplicity and feasibility it was decided not to utilize this technique in the study design. For the same 2? 9 (ÿ0?4^6?3) 1?6 (ÿ2?5^5?8) reason also placebo control was left out of the study. The lack of blindness in comparing the devices may slightly reduce the value of this study since this allows, at least theoretically, some bias to occur in the measurements. The di¡erences in the e⁄cacy measurements between devices were, however, consistent and clear, and also there were no di¡erence in the safety parameters between the devices, which indicates that this fault in the study design had probably no major e¡ect on the results. Since most patients inhaled the ¢rst dose quite early in the morning, in the absence of a placebo it cannot be precluded that natural increase in pulmonary function due to the circadian rhythm (8) might also have contributed to the bronchodilation seen. This, however, has no e¡ect on the between-device comparison and the main results of this study. This is the ¢rst time theTaifuns was compared to any other MDPI. It is considered that the clinical e⁄cacy of inhaled b2 -adrenoceptor agonist drugs is directly related to their lung deposition (9,10). There is no published data available of pulmonary deposition of salbutamol inhaled from theTurbuhalers.However, with terbutaline Turbuhalers previous deposition studies show approximately similar lung drug deposition (21^28%) as with salbutamol Taifuns (24%) (5,11,12). There are some previous studies comparing the relative e⁄cacy of salbutamol Turbuhalers to various other inhalation devices. The Turbuhalers has proven to be a very e⁄cient inhaler since in these studies it has been shown to be about twice as e¡ective as Diskhalers or Rotahalers (13,14), and about two to three times as e¡ective as a pMDI (15). When comparing the Taifuns and the pMDI+S, the results of this study are in accordance with an earlier study (7) where ability of a single dose of 100 mg of salbutamol inhaled via the Taifuns to protect against methacholine-induced bronchoconstriction was found to be clearly better RELATIVE EFFICACYOFA NEW SALBUTAMOL DRY POWDER INHALER compared to that of an equal dose of salbutamol via the pMDI+S (PD20FEV1 1737 mg vs. 622 mg). However, there are no previous studies where the Taifuns has been compared with other powder inhalers, or with a wide range of di¡erent salbutamol doses with any other inhaler devices. When planning the present study it was assumed that the salbutamol Taifuns and Tubuhalers would have approximately the same level of performance. Bearing in mind the results of a previous study (7), it was expected that higher salbutamol doses from the pMDI+S would be needed to gain a similar level of performance as with theTaifuns. Consequently, the doses of salbutamol were selected to start from the smallest available dose from each device and range up to 400 mg for the MDPIs and to 800 mg for the pMDI+S. The hypothesis was that at each dose level salbutamol inhaled via the Taifuns would be at least as e¡ective as salbutamol inhaled via theTurbuhalers or the pMDI+S. Salbutamol inhaled via the Taifuns produced at each dose level greater bronchodilation than equal doses of salbutamol inhaled via the Turbuhalers or twice as high nominal doses from the pMDI+S. At the two lowest doses levels the resulted bronchodilation was signi¢cantly greater with the Taifuns than with the Turbuhalers or the pMDI+S, respectively. Thereafter, towards the higher doses, the di¡erences between the devices diminished, being no longer statistically signi¢cant as the plateau of the dose^ response curve was achieved. On the basis of these results it can be estimated that the relative dose potency of salbutamol from theTaifuns is about twice that of theTurbuhalers and about three times that of the pMDI+S. The overall safety of the tested devices seemed to be similar. The reported drug-related adverse e¡ects were mild and were distributed rather evenly between the devices. In previous studies (16,17) the hypokalaemic e¡ect of inhaled salbutamol (via a pMDI and a spacer) became evident at a dose level of 500 mg or higher. Consequently, some changes in potassium concentrations were expected in the present study. Indeed, potassium concentrations seemed to decrease slightly after the usage of the Taifuns and the pMDI+S, as expected. On the contrary, an unexplained increase was seen after theTurbuhalers. Although the actual changes in serum potassium concentrations with all the devices were small and clinically insigni¢cant, this resulted in a statistically signi¢cant di¡erence in potassium concentrations after salbutamol dosing between the Taifuns and theTurbuhalers. In conclusion, the salbutamol Taifuns was found to be more potent in producing bronchodilaton in asthmatic patients than the salbutamol Turbuhalers or salbutamol pMDI connected to a Volumatics spacer. Approximately two doses from the Turbuhalers and three doses from the pMDI+Volumatics were needed to produce 953 bronchodilation of similar magnitude than a single dose from theTaifuns. It is always an advantage if the patient can be burdened with as small as possible total dose, inhaled and swallowed, of the drug, and still get relief to the symptoms of asthma. All treatments were equally well tolerated. REFERENCES 1. Global initiative for asthma: global strategy for asthma management and prevention. 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Systemic b-adrenoceptor responses to salbutamol given by metered-dose inhaler alone and with pear shaped spacer attachment: comparison of electrocardiographic, hypokalaemic and haemodynamic e¡ects. Br J Clin Pharmacol 1989; 27: 837^ 842. 17. Lipworth BJ,Tregaskis BF, McDevitt DG. b-adrenoceptor responses to inhaled salbutamol in the elderly. Br J Clin Pharmacol 1989; 28: 725^729.