Peak Inspiratory Flow Values Research Articles

Performance of Turbuhaler?? in Patients with Acute Airway Obstruction and COPD, and in Children with Asthma

The dry-powder inhaler (DPI) Turbuhaler((R)) has been on the market for nearly two decades. Products containing terbutaline, formoterol, budesonide, and the combination budesonide/formoterol are widely used by patients with asthma and COPD. Most patients and physicians find Turbuhaler((R)) easy to use, and local side effects are rare. This is thought to arise from the lack of additives or only small amounts in the formulation, in addition to minimal deposition of the drug in the oropharynx and on the vocal cords during inspiration.The function of Turbuhaler((R)) has frequently been questioned. This article aims to review and clarify some key issues that have been challenged in the literature (e.g. the effectiveness of Turbuhaler((R)) in patients with more restricting conditions), to discuss the importance of lung deposition, and to explain the low in vivo variability associated with Turbuhaler((R)) and the lack of correlation with the higher in vitro variability.Turbuhaler((R)), like other DPIs, is flow dependent to some degree. However, a peak inspiratory flow (PIF) through Turbuhaler((R)) of 30 L/min gives a good clinical effect. These PIF values can be obtained by patients with conditions thought to be difficult to manage with inhalational agents, such as asthmatic children and adult patients with acute severe airway obstruction and COPD. Excellent clinical results with Turbuhaler((R)) in large controlled studies in patients with COPD and acute severe airway obstruction provide indirect evidence that medication delivered via Turbuhaler((R)) reaches the target organ.Due to the large amount of small particles and the moderate inbuilt resistance in Turbuhaler((R)), which opens up the vocal cords during inhalation, Turbuhaler((R)) is associated with a high lung deposition (25-40% of the delivered dose) compared with pressurized metered-dose inhalers (pMDIs) and other DPIs. A good correlation has been found between lung deposition and clinical efficacy. A high lung deposition always results in the best ratio between clinical efficacy and risk of unwanted systemic activity. Studies with Turbuhaler((R)) also show that the in vivo variation in lung deposition is significantly lower compared with a pMDI or, for example, the Diskus((R)) inhaler, and much lower than the in vitro dose variability seen in laboratory tests. Turbuhaler((R)) appears to be a reliable DPI which can be used with confidence by patients with airway diseases, including those with clinical conditions believed to be difficult to manage with inhalational therapy.

Ventolin Diskus and Inspyril Turbuhaler: An In Vitro Comparison

Dose delivery (total emitted dose, or TED) from dry powder inhalers (DPIs), pulmonary deposition, and the biological effects depend on drug formulation and device and patient characteristics. The aim of this study was to measure, in vitro, the relationship between parameters of inhalation profiles recorded from patients, the TED and fine particle mass (FPM) of Diskus and Turbuhaler inhalers. Inhalation profiles (IPs) of 25 patients, a representative sample of a wide range of 1500 IPs generated by 10 stable asthmatics, 3 x 16 (mild/moderate/severe) COPD patients and 15 hospitalized patients with an exacerbation asthma or COPD, were selected for each device. These 25 IPs were input IPs for the Electronic Lung (a computerdriven inhalation simulator) to determine particle size distribution from Ventolin Diskus and Inspyril Turbuhaler. The TED and FPM of Diskus and FPM of Turbuhaler were affected by the peak inspiratory flow (PIF) and not by slope of the pressure-time curve, inhaled volume and inhalation time. This flow-dependency was more marked at lower flows (PIF < 40 L/min). Both the TED and FPM of Diskus were significantly higher as compared to those of the Turbuhaler [mean (SD) TED(_diskus) (%label claim) 83.5 (13.9) vs. TED(_turbuhaler) (72.5 (11.1) (p = 0.004), FPM(_diskus) (%label claim) 36.8 (9.8) vs FPM(_turbuhaler) (28.7 (7.7) (p < 0.05)]. The TED and FPM of Diskus and FPM of Turbuhaler were affected by PIF, the flow-dependency being greater at PIF values below 40 L/min. Lower PIFs occurred more often when using Turbuhaler than Diskus, since Turbuhaler have a higher resistivity, requires substantially higher pressure in order to generate the same flow as Diskus. TED, dose consistency and the FPM were higher for Diskus as compared to Turbuhaler. The flow dependency of TED and FPM was substantially influenced by inhalation profiles when not only profiles of the usual outpatient population were included but also the real outliers from exacerbated patients.

Variation of peak inspiratory flow through dry powder inhalers in children with stable and unstable asthma.

Drug release from dry powder inhalers depends for a large part on a sufficiently high peak inspiratory flow (PIF). We determined the variation of PIF through two commonly prescribed dry powder inhalers in children with asthma. We analyzed the effect of inhaler device, age, and severity of asthma symptoms on variation of PIF. Fifty-eight children with asthma (4-15 years old) recorded PIF values together with asthma symptoms in a diary twice daily for 4 weeks. PIF was measured with a portable PIF-meter (In-Check) equipped with adapters to simulate flow resistance through the Accuhaler and Turbohaler inhalers. Children generated higher PIF values through an Accuhaler adapter than through a Turbohaler adapter (95% CI for difference, 25.7-31.7). Mean PIF values increased with age, independent of type of inhaler. The mean (SD) variation of PIF (low%high) was 72.3 (8.1)% for patients using the Accuhaler adapter, and 67.0 (14.5)% for patients using the Turbohaler adapter (mean difference, 5.2%; 95% CI, -0.9 to 11.4). Children < or =7 years of age had a significantly greater variation of PIF in addition to a lower mean PIF (P = 0.0003). PIF decreased significantly when symptoms of asthma increased (mean maximal decrease 11 l/min; P < 0.01), but the correlation between PIF and morning and evening symptoms was weak (r = -0.18 and r = -0.16, respectively). Patients who reported moderate or severe symptoms during the study period had a significantly greater variation of PIF compared to patients who remained free of symptoms or reported mild symptoms. The majority of patients generated PIF >30 l/min during the study, even when they experienced symptoms of asthma. The variation of PIF through the Accuhaler and Turbohaler adapter was significantly greater for children < or =7 years of age and for patients experiencing moderate or severe symptoms of asthma.

Inspiratory flow rate through a dry powder inhaler (Clickhaler) in children with asthma.

Dry powder inhalers (DPIs) are increasingly being used to deliver drugs for the treatment of asthma. Both the aerosolization and delivery of the drug from a DPI to the lung are dependent on an adequate inspiratory effort from the patient, and it is well-known that the air flow achieved early in the inspiratory profile is important in determining particle size distribution from the inhaler. The present study assessed the peak inspiratory flow (PIF) generated through the Clickhaler DPI, and the early inspiratory flow at 150 mL of inspired volume (IF(150)), in asthmatic children. These measurements were made in a well-controlled setting, and two attempts were recorded to establish maximum achievement. Results were obtained from 57 children aged 6-17 years, showing a (mean +/- SD) best PIF of 60.5 +/- 18.7 L/min (range, 26.8-97.0). The mean PIF overall was 54.2 +/- 20.8 L/min (7.9-97.0). For children aged 6-8 years, the mean best PIF was 46.5 +/- 14.6 L/min (26.8-71.1); for those aged 9 years or more, it was >65 L/min (30.3-97.0). PIF values were unrelated to % predicted FEV(1) measurements. Best IF(150) (mean +/- SD) was 42.9 +/- 13.6 L/min (23.1-66.6) in children aged 6-8 years, and >55 L/min (28.0-86.4) for the older children, showing that high flow rates were achieved early in the inspiratory profile. These data indicate that children with stable asthma can generate adequate inspiratory flow rates to operate the Clickhaler effectively.

Intranasal fluticasone propionate versus loratadine in the treatment of adolescent patients with seasonal allergic rhinitis

Fluticasone propionate (FP) is a topical corticosteroid with minimal systemic activity. We examined safety and compared the efficacy of FP aqueous nasal spray, 200 μg every day with loratadine tablets, 10 mg by mouth every day in 240 adolescents with ragweed pollen–induced seasonal allergic rhinitis for 4 weeks in a randomized, double-blind, parallel-group study. Nasal and eye symptoms were recorded daily on a 4-point (0 to 3) scale. A higher percentage of symptom-free days was observed for nasal blockage on waking during treatment with FP ( p < 0.0001). Significant results were also obtained for all other nasal symptoms when analyzed for both symptom-free days and symptom scores. No differences were found for eye irritation symptoms ( p = 0.14). Morning and evening nasal peak inspiratory flow (PIF) was recorded daily by 57 subjects. FP treatment was associated with significantly higher PIF values than loratadine both morning ( p = 0.0051) and evening ( p = 0.0036). A greater improvement over 4 weeks was observed for PIF morning values in the FP group ( p = 0.008) but not for evening values ( p = 0.358). Statistically significant correlations were found for nasal blockage and PIF in the morning ( r = -0.54, p = 0.0001) and in the evening ( r= -0.46, p = 0.008). (J A LLERGY C LIN I MMUNOL 1996;97:588-95.)