In vitro aerodynamic characterization of the dose emitted during nebulization of tobramycin high strength solution by novel and jet nebulizer delivery systems.

BACKGROUND: Chronic infections with Pseudomonas aeruginosa are a leading cause of morbidity in patients with cystic fibrosis (CF). The aim of tobramycin inhalation therapy in CF patients with chronic pulmonary infection is to deliver high amounts of drug directly to the site of infection. TOBI(®) is a tobramycin nebulizer solution (300 mg/5 ml) approved by FDA for maintenance therapy for patient with CF. The 20% tobramycin sulfate solution was reported as the optimal and maximal concentration. METHODS: Nebulization of high strength tobramycin solution (20% tobramycin sulfate) (HSTS) has been assessed in this study by using different selected high performance nebulizer delivery systems: two different designs of jet nebulizers, and three new nebulizers based on vibrating mesh technology. The aerosol particle size distribution and output characteristics were measured for in vitro performance assessment of the nebulizer systems. The methodology was adapted from the current European standard, EN 13544-1:2001E. RESULTS: The particle size distribution characteristic measurements showed that all tested nebulizers may be suitable for inhalation of HSTS. The mean (SD) of highest percentage of fine particles (<5 µm) was 77.64 (2.3) % for Sidestream(®), at flow rate 16 L/min. The highest respirable inhaled mass was for Pari LC Plus(®) combined with PariBoyN(®) compressor, with mean (SD) 90.85 (8.6) mg. The mean (SD) of highest drug wastage percentage was 63.9 (3.9) % for Sidestream(®) jet nebulizer combined with compressed air cylinder at flow rate 16 L/min, while the lowest was 2.3 (0.26) % for NE-U22 Omron(®) (high frequency). CONCLUSIONS: The HSTS can be nebulized by all tested nebulisers but the high frequency NE-U22 Omron(®) and Aeroneb Go(®) are more efficient. When the HSTS compared to TOBI(®), the respirable inhaled dose was increased to more than 73%.

The economic burden of asthma and chronic obstructive pulmonary disease and the impact of poor inhalation technique with commonly prescribed dry powder inhalers in three European countries.

BACKGROUND: Asthma and chronic obstructive pulmonary disease (COPD) are common chronic inflammatory respiratory diseases, which impose a substantial burden on healthcare systems and society. Fixed-dose combinations (FDCs) of inhaled corticosteroids (ICS) and long-acting ß2 agonists (LABA), often administered using dry powder inhalers (DPIs), are frequently prescribed to control persistent asthma and COPD. Use of DPIs has been associated with poor inhalation technique, which can lead to increased healthcare resource use and costs. METHODS: A model was developed to estimate the healthcare resource use and costs associated with asthma and COPD management in people using commonly prescribed DPIs (budesonide + formoterol Turbuhaler(®) or fluticasone + salmeterol Accuhaler(®)) over 1 year in Spain, Sweden and the United Kingdom (UK). The model considered direct costs (inhaler acquisition costs and scheduled and unscheduled healthcare costs), indirect costs (productive days lost), and estimated the contribution of poor inhalation technique to the burden of illness. RESULTS: The direct cost burden of managing asthma and COPD for people using budesonide + formoterol Turbuhaler(®) or fluticasone + salmeterol Accuhaler(®) in 2015 was estimated at €813 million, €560 million, and €774 million for Spain, Sweden and the UK, respectively. Poor inhalation technique comprised 2.2-7.7 % of direct costs, totalling €105 million across the three countries. When lost productivity costs were included, total expenditure increased to €1.4 billion, €1.7 billion and €3.3 billion in Spain, Sweden and the UK, respectively, with €782 million attributable to poor inhalation technique across the three countries. Sensitivity analyses showed that the model results were most sensitive to changes in the proportion of patients prescribed ICS and LABA FDCs, and least sensitive to differences in the number of antimicrobials and oral corticosteroids prescribed. CONCLUSIONS: The cost of managing asthma and COPD using commonly prescribed DPIs is considerable. A substantial, and avoidable, contributor to this burden is poor inhalation technique. Measures that can improve inhalation technique with current DPIs, such as easier-to-use inhalers or better patient training, could offer benefits to patients and healthcare providers through improving disease outcomes and lowering costs.

Dose emission and aerodynamic characterization of the terbutaline sulphate dose emitted from a Turbuhaler at low inhalation flow.

Previously, dose emission below 30 L min(-1) through DPI has not been routinely determined. However, during routine use some patients do not achieve 30 L min(-1) inhalation flows. Hence, the aim of the present study was to determine dose emission characteristics for low inhalation flows from terbutaline sulphate Turbuhaler. Total emitted dose (TED), fine particle dose (FPD) and mass median aerodynamic diameter (MMAD) of terbutaline sulphate Turbuhaler were determined using inhalation flows of 10-60 L min(-1) and inhaled volume of 4 L. TED and FPD increase significantly with the increase of inhalation flows (p <0.05). Flows had more pronounced effect on FPD than TED, thus, faster inhalation increases respirable amount more than it increases emitted dose. MMAD increases with decrease of inhalation flow until flow of 20L min(-1) then it decreases. In vitro flow dependent dose emission has been demonstrated previously for Turbuhaler for flow rates above 30 L min(-1) but is more pronounced below this flow. Minimal FPD below 30 L min(-1) suggests that during routine use at this flow rate most of emitted dose will impact in mouth. Flow dependent dose emission results suggest that Pharmacopoeias should consider the use variety of inhalation flows rather than one that is equivalent to pressure drop of 4 KPa.

The Genuair® inhaler: a novel, multidose dry powder inhaler.

This article reviews the Genuair(®) inhaler, a novel, multidose, breath-actuated dry powder inhaler. The inhaler design includes visual and acoustic feedback to reassure patients that they have taken their medication correctly, a dose indicator and a lock-out mechanism to prevent the use of an empty inhaler. The inhaler has medium airflow resistance and uses an optimised dispersion system to ensure effective deagglomeration of the inhalation powder. In vitro studies have demonstrated that the inhaler delivers a reproducible aerodynamic aerosol quality and is reliable under various thermal and mechanical stress conditions. Further studies in vitro have demonstrated that the total emitted dose and fine particle dose are both consistent over a range of inhalation flows from 45 to 95 l/min, as well as being independent of inhalation volume (2 l vs. 4 l) and storage conditions. In healthy subjects, delivery of aclidinium bromide 200 µg via the inhaler achieved high lung deposition (approximately 30% of the metered dose). A further study has shown that patients with moderate or severe chronic obstructive pulmonary disease can generate sufficient inspiratory airflow through the inhaler to reliably inhale the full dose and reset the inhaler. The inhaler has been used to deliver aclidinium in many clinical trials and the available data indicate that it has high acceptability amongst patients.

The impact of inhaler technique on clinical outcomes in adolescents and adults with asthma: A systematic review.

BACKGROUND: Many patients with asthma use their inhalers incorrectly, which can lead to sub-optimal asthma control and an increased risk of exacerbations. The Accuhaler/Diskus and Turbuhaler are arguably two of the most commonly used dry powder inhalers worldwide. METHODS: A systematic literature review (SLR) was conducted to assess the impact of inhalation errors with these dry powder inhalers on clinical outcomes in asthma. Database searches were conducted in MEDLINE, Embase and proceedings from scientific conferences. Observational studies in adults and adolescents with asthma, reporting data for Accuhaler/Diskus and Turbuhaler devices and at least one outcome of interest, were included. Dual-independent screening and validation of studies was performed. RESULTS: The search identified 35 studies. A range of inhaler errors was observed across studies and devices. In 8 out of the 9 studies that involved the two devices, the percentage of overall inhaler error rates was numerically (7 studies) or significantly (1 study) higher for Turbuhaler than Diskus, ranging from 3.7% to 71.9% for Diskus and 1.2%-83% for Turbuhaler. Critical errors, reported in three studies using similar definitions, ranged from 20% to 43% for Diskus and 32%-100% for Turbuhaler. Five studies reported a significant association between inhaler errors and worse asthma control, while one showed no difference. CONCLUSIONS: This SLR identified a large range of inhaler errors with both devices. Across devices, a better inhalation technique was associated with better asthma outcomes. This systematic review confirms the importance of patients using their inhalers correctly as an integral part of achieving optimal asthma outcomes.

What the pulmonary specialist should know about the new inhalation therapies.

A collaboration of multidisciplinary experts on the delivery of pharmaceutical aerosols was facilitated by the European Respiratory Society (ERS) and the International Society for Aerosols in Medicine (ISAM), in order to draw up a consensus statement with clear, up-to-date recommendations that enable the pulmonary physician to choose the type of aerosol delivery device that is most suitable for their patient. The focus of the consensus statement is the patient-use aspect of the aerosol delivery devices that are currently available. The subject was divided into different topics, which were in turn assigned to at least two experts. The authors searched the literature according to their own strategies, with no central literature review being performed. To achieve consensus, draft reports and recommendations were reviewed and voted on by the entire panel. Specific recommendations for use of the devices can be found throughout the statement. Healthcare providers should ensure that their patients can and will use these devices correctly. This requires that the clinician: is aware of the devices that are currently available to deliver the prescribed drugs; knows the various techniques that are appropriate for each device; is able to evaluate the patient's inhalation technique to be sure they are using the devices properly; and ensures that the inhalation method is appropriate for each patient.

Development and validation of HPLC method for the determination of tobramycin in urine samples post-inhalation using pre-column derivatisation with fluorescein isothiocyanate.

A reversed-phase liquid chromatography method involving pre-column derivatisation with fluorescein isothiocyanate (FITC, isomer I) for determination of tobramycin in urine samples after inhalation has been developed. FITC reacts with the primary amino groups of tobramycin and other aminoglycosides under mild conditions to form a highly fluorescent and stable derivative. The chromatographic separation was carried out on a Phenomenex Luna C(18) column at ambient temperature using a constant flow rate of 1 ml/min and mobile phase of acetonitrile-methanol-glacial acetic acid-water (420:60:5:515, v/v/v/v). The tobramycin-FITC derivative was monitored by fluorescent detection at an excitation wavelength 490 nm and emission wavelength 518 nm. The linearity of response for tobramycin was demonstrated at 11 different concentrations of tobramycin extracted from spiked urine, ranging from 0.25 to 20 microg/ml. Tobramycin and neomycin were extracted from spiked urine by a solid phase extraction clean-up procedure on a carboxypropyl-bonded phase (CBA) weak cation-exchange cartridge, and the relative recovery was >99% (n=5). The limit of detection (LOD) and limit of quantitation (LOQ) in urine were 70 and 250 ng/ml, respectively. The method had an accuracy of <0.2%, and intra-day and inter-day precision (in term of %coefficient of variation) were <4.89% and 8.25%, respectively. This assay was used for urinary pharmacokinetic studies to identify the relative lung deposition of tobramycin post-inhalation of tobramycin inhaled solution 300 mg/5 ml (TOBI) by different nebuliser systems.

Validation of high-performance liquid chromatography assay for quantification of formoterol in urine samples after inhalation using UV detection technique.

A novel high-performance liquid chromatography (HPLC) assay for the estimation of formoterol in urine samples was developed and validated. A solid phase extraction (SPE) using Oasis HLB was optimised to isolate formoterol from a urine matrix followed by HPLC with UV detection. This extraction procedure concentrated the final analyte forty times so that UV detection can be used to determine even a low concentration of formoterol in urine samples. The urinary assay was performed in accordance with FDA and ICH regulations for the validation of bioanalytical samples. The samples were injected onto a C18 Spherisorb (250 mm x 4.6 mm x 5 microm) analytical column maintained at 30 degrees C. The mobile phase consisted of 5 mM of potassium dihydrogen orthophosphate buffer (adjusted to pH 3 with ortho phosphoric acid):acetonitrile (ACN) (70:30, v/v), and the formoterol peak was detected at wavelength 214 nm. The extraction recovery of formoterol from the urine sample was >95%. The calibration curve was linear (r2=0.99) over formoterol concentrations ranging from 1.5 to 25 ng/mL (n=6). The method had an accuracy of >92% and intra and inter-day precision CV% of <3.9% and <2.2%, respectively, at three different concentrations low, medium and high (10, 15, 20 ng/mL). The limit of quantification (LOQ) for formoterol was found to be 1.50 ng/mL. The accuracy and precision at the LOQ level were 95% and %CV <3.7% (n=10), respectively. The method reported is simple, reliable, precise, and accurate and has the capacity to be used for determination of formoterol in urine samples.

Budesonide + formoterol delivered via Spiromax® for the management of asthma and COPD: The potential impact on unscheduled healthcare costs of improving inhalation technique compared with Turbuhaler®.

BACKGROUND: Fixed-dose combinations of inhaled corticosteroids and long-acting ß2 agonists are commonly used for the treatment of asthma and COPD. However, the most frequently prescribed dry powder inhaler delivering this medicine - Symbicort® (budesonide and formoterol, BF) Turbuhaler® - is associated with poor inhalation technique, which can lead to poor disease control and high disease management costs. A recent study showed that patients make fewer inhaler errors when using the novel DuoResp® (BF) Spiromax® inhaler, compared with BF Turbuhaler®. Therefore switching patients from BF Turbuhaler® to BF Spiromax® could improve inhalation technique, and potentially lead to better disease control and healthcare cost savings. METHODS: A model was developed to estimate the budget impact of reducing poor inhalation technique by switching asthma and COPD patients from BF Turbuhaler® to BF Spiromax® over three years in Germany, Italy, Sweden and the UK. The model estimated changes to the number, and associated cost, of unscheduled healthcare events. The model considered two scenarios: in Scenario 1, all patients were immediately switched from BF Turbuhaler® to BF Spiromax®; in Scenario 2, 4%, 8% and 12% of patients were switched in years 1, 2 and 3 of the model, respectively. RESULTS: In Scenario 1, per patient cost savings amounted to €60.10, €49.67, €94.14 and €38.20 in Germany, Italy, Sweden and the UK, respectively. Total cost savings in each country were €100.86 million, €19.42 million, €36.65 million and €15.44 million over three years, respectively, with an estimated 597,754, 151,480, 228,986 and 122,368 healthcare events avoided. In Scenario 2, cost savings totalled €8.07 million, €1.55 million, €2.93 million and €1.23 million over three years, respectively, with 47,850, 12,118, 18,319, and 9789 healthcare events avoided. Savings per patient were €4.81, €3.97, €7.53 and €3.06. CONCLUSIONS: We demonstrated that reductions in poor inhalation technique by switching patients from BF Turbuhaler® to BF Spiromax® are likely to improve patients' disease control and generate considerable cost savings through healthcare events avoided.

High performance liquid chromatography assay method for simultaneous quantitation of formoterol and budesonide in Symbicort Turbuhaler.

A sensitive and rapid high performance liquid chromatography method has been developed and used for the simultaneous determination of formoterol and budesonide in Symbicort Turbuhaler when assessing the aerodynamic characteristics of the emitted dose using Pharmacopoeial methods. This capability results in both time and cost saving. The mobile phase composition was acetonitrile-5 mM sodium dihydrogen orthophosphate, pH 3 (60: 40% v/v), and was passed at 1.5 ml min(-1) through a C18 column with a UV detection (wavelength 214 nm). The method was shown to give good analytical performance in terms of linearity, precision (using phenylpropanolamine as an internal standard), sensitivity and solution stability. The intra-day precision for both formoterol and budesonide were 0.75% and 1.11%, respectively (n = 10). The limit of quantitation for formoterol was 10 microgL(-1) and for budesonide was 120 microgL(-1), and the limit of detection were 3 and 30 microgL(-1), for both formoterol and budesonide, respectively. The method has been applied to determine the content of the emitted dose and the fine particle dose of Symbicort Turbuhaler.

The relationship between the quality of prescribing and practice appointment rates with asthma management data in those admitted to hospital due to an acute exacerbation.

Specific targeting of patients with a previous asthma hospitalisation could be more focused if predictors could be identified. This study was an observational retrospective analysis using ridge and linear multivariate regression analysis. Patient asthma management data were extracted from the hospital and general practice notes of those that had been admitted with an acute exacerbation of their asthma over a 5-year period. From the prescribing data, the annual doses of preventer (P) and reliever (R) medication were converted to defined daily doses then divided to give a P:R ratio. Preliminary statistical analysis was used to identify any association between either the P:R ratio or for the number of general practitioner (GP) practice appointments (PA) and their asthma management data. Multivariate regression analysis was applied to the P:R ratio and to PA to determine a model between each of these and asthma management data/events. GPs gave consent to access the data of 115 (out of 440) asthmatics, age >5 years, admitted to a district general hospital for asthma exacerbations between 1994 and 1998. The multivariate analysis revealed that PA was associated with oral prednisolone rescue courses (PRCs) and age whilst the P:R ratio was associated to PRCs and more reliever usage but not preventers. Patients with low preventer usage with respect to their reliever medication should be targeted for medication review as these were the patients prescribed more prednisolone courses and their increased PAs reflect this. This could decrease visits to the doctor and acute exacerbations.

Do patients show the same level of adherence with all dry powder inhalers?

Poor adherence with inhaled therapy presents a considerable problem. In the UK, non-adherence is estimated to occur in 10-46% of those prescribed inhaled corticosteroids and may contribute to an estimated 18-48% of asthma deaths. Before dry powder inhalers can be considered interchangeable, it is important to check that adherence is unaffected by any switching of the device dispensed to patients. Numerous studies have shown that adherence with inhaled medication is a multifactorial issue. A number of evidence-based guidelines have concluded that there is no difference in the delivery of treatments from different inhaler devices. However, many studies comparing different devices are designed to show equivalence. It is therefore difficult to determine whether the studies on which the guidelines are based were conducted with treatments already being used at the top of a dose-response curve. Furthermore, studies use selected patient populations who consent to take part and consequently receive regular contact with healthcare professionals, with emphasis on using the correct inhaler technique and on compliance. These studies do not therefore necessarily reflect real life. It is possible that patient preferences or perceptions of differences in efficacy are behind complaints when devices are switched. Patients vary in their preference for different dry powder inhalers, as shown in numerous studies of patient attitudes. There is evidence to indicate that patient claims of differences between inhalers that contain the same molecule from different manufacturers may have an objective basis. Healthcare professionals increasingly recognise the impact of patient attitudes on adherence. Accepting that patients make choices about their therapy is an integral part of achieving the partnership in management recommended by guidelines. The most effective treatment will not achieve disease control if it is not used or if it is used incorrectly. It may be short-sighted to change a device that a patient has chosen to one that is just given without consent, as this may result in poor adherence to therapy with consequent loss of control.

Can patients use all dry powder inhalers equally well?

If patients are unable to use their inhaler, drug delivery may be unsatisfactory and the patients may fail to benefit from the prescribed medication. It is important to consider whether patients can use all dry powder inhalers equally well. Changing a patient from a dry powder inhaler used well to one that the patient is unable to operate effectively could compromise asthma control. The many marketed dry powder inhalers reflect differences in design decisions that could affect lung deposition. Studies using different dry powder inhalers have confirmed that different lung deposition patterns are observed. Furthermore, there may be considerable individual variability in lung deposition. Differences in lung deposition patterns could have clinical effects. Studies may show similar clinical effectiveness with two inhalers, because most products are used at the plateau phase of the dose-response curve, although there may be differences in the adverse event profile. The ideal inhaler does not yet exist. Different dry powder inhalers show some but not all features of the ideal inhaler; hence, patients may prefer some aspects of one inhaler while favouring a different inhaler for other features. The individual balance of features will govern the overall preference for one inhaler over others. The method for operation of dry powder inhalers varies. Ease of use is seen as an important consideration when selecting an inhaler device, which should be evaluated in real-life studies using unselected patient populations. In conclusion, the evidence suggests that patients cannot use all dry powder inhalers equally well.

Ondansetron therapy for uremic pruritus in hemodialysis patients.

Pruritus is a distressing symptom affecting up to 90% of dialysis patients. Conventional treatment with antihistamines is often ineffective and may have unacceptable side effects. Serotonin (5-hydroxytryptamine type 3 [5-HT(3)]) is known to enhance pain perception and pruritic symptoms through receptors on sensory nerve endings. Antagonism of 5-HT(3) receptors may be of use in treating uremic pruritus. We randomly assigned 16 hemodialysis patients with persistent pruritus to treatment with the 5-HT(3)-receptor antagonist, ondansetron (8 mg), or placebo three times daily for 2 weeks each in a prospective, placebo-controlled, double-blind crossover study. Patients scored their intensity of pruritus daily on a 0-to-10 visual analogue scale (0 = no pruritus, 10 = maximal pruritus), and daily use of antihistamines as escape medication was recorded. The median daily pruritus score did not change significantly during active or placebo treatment (preondansetron, 5. 3; interquartile range [IQR], 3.4 to 6.3; during ondansetron, 3.9; IQR, 2.7 to 5.0; P = not significant; preplacebo, 3.7; IQR, 3.0 to 4. 6; during placebo, 3.6; IQR, 2.4 to 4.8; P = not significant). The median daily percentage of escape medication use decreased from 21% (IQR, 9 to 61) to 9% (IQR, 0 to 33) with ondansetron (P = not significant) and from 53% (IQR, 0 to 88) to 5% (IQR, 0 to 31) with placebo (P = not significant). There was no difference in predialysis biochemistry test results or dialysis efficacy during treatment phases. Ondansetron does not improve pruritus in hemodialysis patients. Use of antihistamines decreased with both ondansetron and placebo.

Dry powder inhalers are bioequivalent to metered-dose inhalers. A study using a new urinary albuterol (salbutamol) assay technique.

Metered-dose inhalers (MDIs) are extensively used to deliver drugs to the lungs but are driven by chlorofluorocarbon (CFC) propellants. The worldwide phasing out of CFCs within the next 5 to 10 years presents difficulties to the pharmaceutical industry. The mean +/- SD relative lung bioavailability of albuterol to the lung following inhalation of 400 micrograms of albuterol from an MDI, the Rotahaler and Diskhaler in 10 well-trained volunteers, was 2.83 (0.78), 1.72 (0.99), and 2.64 (1.23)%, respectively, expressed as a percentage of the nominal dose. The delivery of albuterol to the lungs from the MDI and Diskhaler was similar. In nine asthmatic subjects, the relative lung bioavailability of albuterol following inhalation with the MDI and Diskhaler was 1.19 (0.79) and 2.38 (1.46)%, respectively, expressed as a percentage of the nominal dose. There was no difference in reversibility 30 min after administration of the dose by the two methods. Similar lung deposition from the Diskhaler in volunteers probably is due to efficient MDI technique, which was absent in the asthmatic subjects. The Diskhaler does not rely on coordination during inhalation and therefore is easier to use.

Ifosfamide enantiomers: pharmacokinetics in children.

Ifosfamide, like other oxazaphosphorine drugs, is chiral and there is some evidence, mainly from animal studies, of stereo-selective differences in metabolism, excretion and cytotoxic activity between the two enantiomers. The pharmacokinetics of racemic ifosfamide (RAC-IFO), R-ifosfamide (R-IFO) and S-ifosfamide (S-IFO) were studied in five children who received intravenous therapy with racemic ifosfamide on 3 consecutive days. The clearance of S-IFO was greater than that of R-IFO. The clearance value at the end of the infusion was faster than the respective rate measured at the beginning of or during the ifosfamide regimens in four children and, therefore, suggests autoinduction of elimination of both enantiomers.

Is inhalation rate important for a dry powder inhaler? Using the In-Check Dial to identify these rates.

The fraction of the emitted dose from an inhaler that has the potential to be deposited into the lungs is known as the fine particle dose (also the respirable dose). During inhalation all dry powder inhalers require a 'force' to be created inside the device so that a fine particle dose is generated from the formulation in the metering chamber. This 'force' is formed by the inhalation rate used together with the resistance (and hence design) inside an inhaler. Studies have shown that the fine particle dose is related to the clinical effect whilst other studies have reported that this dose can be dependent on the inhalation rate used. The inhalation technique recommended by the manufacturer of an inhaled device should, therefore, be used. For those dry powder inhalers that demonstrate significant flow dependent dosage emission it is important that patients use the most desirable rate that has been reported. The In-Check Dial is a simple and ease to use meter that can be used to measure the inhalation rate of a patient when they use each of the commonly prescribed inhalers that are currently available. This meter can be used to identify the most suitable inhaler for each individual.

The relative bioavailability of salbutamol to the lung using urinary excretion following inhalation from a novel dry powder inhaler: the effect of inhalation rate and formulation.

Each dry powder inhaler has a different resistance so that a respirable dose can be generated from the formulation by the patient's inspiratory effort. It is important to recognize that this effect is achievable. The inspiratory flow characteristics of asthmatics inhaling through a Clickhaler were determined. In a separate study 10 volunteers inhaled separate 2 x 100 microg salbutamol doses from a Clickhaler (ML Laboratories plc U.K.). Two different formulations (one with a high and one with a low respirable fraction) were each inhaled using an inspiratory flow of 30 and 60 l min(-1). A urine sample was collected 30 min post inhalation and then pooled for the next 24 h. The mean (SD) inhalation rate of 24 asthmatics when they inhaled from a Clickhaler was 37.3 (14.6) l min(-1). The mean (SD) urinary salbutamol excretion during the first 30 min, by the volunteers, using the high respirable dose formulation at 30 and 60 l min(-1) was 5.59 (1.87) and 4.62 (1.49) microg respectively (P<0.01). Similar values using the low respirable dose formulation were 4.84 (1.58) and 3.86 (2.14) microg. There was no significant difference between the amounts excreted in the 24 h post-dose. The different 30-min urinary excretions following inhalation of the two formulations suggest a link between the relative bioavailability of salbutamol to the lung and the respirable dose, and that a slow inhalation rate should be used when using a Clickhaler. The patient study shows that this rate is achieved by most asthmatics without further training.

Characterization of the inspiratory manoeuvre when asthmatics inhale through a Turbohaler pre- and post-counselling in a community pharmacy.

Dose emission from a Turbohaler has been shown to be dependent on the rate of inhalation, with an optimal flow of 60 l min(-1) recommended. Some patients may need counselling to achieve this fast inhalation. Inhalation rate profiles of 24 asthmatics were measured when they inhaled through a placebo Turbohaler. The setting was a community pharmacy when the asthmatics came to collect their next supply of medication. Profiles were measured before and after counselling on how to use the Turbohaler. The mean (SD) peak inhalation rate through the Turbohaler pre- and post-counselling was 48.0 (16.8) and 54.7 (17.6) l min(-1), and their inspiratory volume was 1.75 (0.68) and 1.94 (0.62) l, respectively. Their mean (SD) percent predicted FEV1 was 57.0 (18.9)%. After counselling, 12 patients achieved an inhalation rate of > 60 l min(-1) and a further four obtained > 55 l min(-1). Emphasis should be placed on counselling patients prescribed all types of inhaled devices rather than concentrating on metered dose inhalers.

Measurement of peak inhalation rates with an in-check meter to identify an elderly patient's ability to use a turbuhaler.

Dry powder inhalers are designed with resistance to airflow so that a respirable cloud of particles is generated during inhalation. Some of these devices require a certain inhalation rate to produce a consistent dose of respirable particles. The aim of the study was to determine the inhalation rate of elderly patients with chronic obstructive pulmonary disease (COPD) when they inhale through a Turbuhaler and assess the potential of the In-Check Meter to identify inhalation rates. Their peak inhalation rate using a normal inhalation, pre- and post-counselling, was measured using a Turbuhaler Trainer and an In-Check Meter. Spirometry was also measured. Seventy-four COPD patients with a mean (SD) age of 79.7 (8.4) years and forced expiratory volume in 1 sec (FEV1) 41.9 (12.8)% predicted. Pre-counselling 14 obtained a rate of <30 l min(-1) with the Turbuhaler Trainer, 31 from 30 to 40 min(-1), 23 between 40-60 l min(-1) and 6 > 60 l min(-1). The median (range) peak inhalation rates with the In-Check Meter were 50 (50-70), 70 (50-130), 100 (60-200) and 225 (200-250) l min(-1). Post-counselling 7, 16,41 and 10 achieved the respective peak inhalation rates using the Turbuhaler Trainer Similarly the In-Check inhalation rates were 50 (50-60), 70 (50-130), 90 (60-200) and 250 (200-270) l min(-1). The results highlight the potential of the In-Check Meter to identify patients' inhalation rates through dry powder inhalers.