Single-dose pharmacokinetics and safety pharmacodynamics of formoterol delivered by two different dry powder inhalers

The present study aimed at assessing the pharmacokinetics (PK) and safety pharmacodynamics (PD) of 24 microg formoterol delivered via a Novolizer and via an Aerolizer in healthy subjects. This was a randomized, open-label, crossover study. Beside PK, serum potassium, and glucose profiles, vital signs, and ECG were recorded. Twenty-nine subjects (15 males) were enrolled. The inhalation maneuver had to be repeated by 19 subjects using the Aerolizer and 1 subject using a Novolizer. While eight (28%) subjects completely failed to inhale correctly via the Aerolizer (four were identified by the investigators immediately after inhalation, another four by bioanalytics later), all did it correctly via the Novolizer. The bioanalytical evaluation indicated two distinct serum peaks. The shapes of serum concentration-time profiles were more homogeneous after inhaling via the Novolizer than via the Aerolizer. After adjusting for the delivered dose the Cmax of formoterol predicting pulmonary absorption was higher after the Novolizer than after the Aerolizer, while the average AUC0-infinity levels indicating total systemic exposure were equivalent. There was no evidence for different pharmacodynamic behavior with respect to serum potassium and glucose profiles, vital signs, and ECG. The Novolizer yields higher pulmonary absorption of formoterol than the Aerolizer and equivalent safety profiles. Considering the lower variability of PK profiles and the higher proportion of correct inhalations, formoterol is more reliably inhaled via Novolizer.     

In vitro-in vivo correlation of the pharmacokinetics of vinpocetine

Vinpocetine is extensively metabolized in rats, dogs and humans, and the plasma clearance approximates the hepatic plasma flow in each of the species. In vitro degradation studies with hepatocytes have shown that the activity of human hepatocytes is about one order of magnitude higher than the activity of dog hepatocytes, and two orders of magnitude higher than that of rat hepatocytes. These differences can explain the differences in bioavailabilities of vinpocetine in the three species (52% in rats, 21.5+/-19.3% in dogs and 6.2+/-1.9% in humans). In dogs and humans, the compound seems to be metabolized exclusively in the liver whereas in rats extrahepatic metabolism seems also to be important. The in vivo clearance predicted from the activity of hepatocytes is in good agreement with the values measured in vivo in the case of humans and dogs. The estimated values for bioavailability showed good correlation with in vivo data in each species if the free drug ratio was assumed to equal 1.     

Review of dry powder inhalers

The search for alternatives to metered-dose inhalers has accelerated recently in a bid to find effective products that do not use chlorofluorocarbon (CFC) propellants. This paper reviews the factors to be considered in developing dry powder inhalers (DPIs), particularly the formulation, metering design and flow path in the device. The advantages and disadvantages of current DPIs are discussed and possible future approaches outlined.     

Pharmacokinetics and pharmacodynamics analysis of transdermal iontophoresis of 5-OH-DPAT in rats: in vitro-in vivo correlation

Pharmacokinetics and dopaminergic effect of dopamine agonist 5-OH-DPAT in vivo were determined following transdermal iontophoresis in rats based on drug concentration in plasma (C(p)) and dopamine levels in striatum (C(DA)). Correlation of the in vitro transport with the pharmacokinetic-pharmacodynamic (PK-PD) profiles was characterized in the transport in dermatomed rat skin (DRS) and rat stratum corneum (RSC). The integrated in vivo PK-PD and in vitro transport models successfully described time course of C(p), C(DA), and in vitro flux in DRS and RSC. Population value of steady-state flux (J(ss)) in vivo (31 nmol/cm(2) . h with 95% confidence interval (CI) = 20-41) is closer to J(ss) in vitro in DRS (61 nmol/cm(2) . h, CI = 54-67) than in vitro J(ss) in RSC (98 nmol/cm(2) . h, CI = 79-117). On the other hand, skin release rate constant (K(R)) in vivo was similar to the K(R) in RSC (4.8/h, CI = 2.4-7.1 vs. 2.6/h, CI = 2.5-2.6). Kinetic lag time (t(L)) in vivo was negligible, which is close to in vitro t(L) in RSC (0.0 h, CI = 0.0-0.1). Based on nonlinear mixed-effect modeling, profiles of C(p) and C(DA) were successfully predicted using in vitro values of J(ss) in DRS with K(R) and t(L) in RSC. A considerable dopaminergic effect was achieved, indicating the feasibility to reach therapeutically effective concentrations of 5-OH-DPAT upon transdermal iontophoresis.     

Pulmonary delivery of inhalable nanoparticles: dry powder inhalers

Pulmonary administration of inhalable nanoparticles (NPs) is an emerging area of interest. Dry powder inhalers may offer particular advantages for pulmonary administration of NPs. This article reviews research performed on the formulation of inhalable NPs as dry powder to achieve deep-lung deposition and enhance NP redispersibility. Moreover, the article summarizes up-to-date in vivo applications of inhalable NPs as dry powder inhalers.     

Equivalence testing of salbutamol dry powder inhalers: in vitro impaction results versus in vivo efficacy

The aim of the study was to evaluate several impactors for in vitro equivalence testing of salbutamol with respect to efficacy and to define in vitro equivalence limits validated with in vivo efficacy data. The four impactors described in Supplement 2000 of the European Pharmacopoeia were used: Glass Impinger (GI), Metal Impinger (MI), Multistage Liquid Impinger (MSLI) and Andersen Cascade Impactor (ACI). Three salbutamol dry powder formulations with different fine particle doses (FPDs) were prepared and the aerodynamic particle size distribution was measured. For each impactor also the recovery was determined. The same three preparations were administered to 12 asthmatic patients in a randomized, placebo-controlled, four-way crossover study. Cumulative doses from 50 microg up to 400 microg were given. The FEV(1) was measured at baseline and 15 min after each dose. The in vitro results showed large differences between the FPDs of the three preparations with all impactors, whereas only small differences were observed between the four impactors. Since the recoveries of the MI and GI were low, in vitro equivalence testing should only be performed with the MSLI or ACI. The in vivo measurements did not show significant differences in efficacy between the three active preparations, even at the most discriminatory dose of 50 microg. It is concluded that in case there are no relevant differences between delivered dose, inhalation device and excipients, for salbutamol dry powder inhalers equivalence can be assumed when the 90% confidence interval for the FPD ratio of the test product and reference product is within 0.50-1.20 and each of the two products has a FPD (particles <6 microm) of at least 10 microg.     

The use of colloid probe microscopy to predict aerosolization performance in dry powder inhalers: AFM and in vitro correlation

The atomic force microscope (AFM) colloid probe technique was utilized to measure cohesion forces (separation energy) between three drug systems as a function of relative humidity (RH). The subsequent data was correlated with in vitro aerosolization data collected over the same RH range. Three drug-only systems were chosen for study; salbutamol sulphate (SS), triamcinolone acetonide (TAA), and di-sodium cromoglycate (DSCG). Analysis of the AFM and in vitro data suggested good correlations, with the separation energy being related inversely to the aerosolization performance (measured as fine particle fraction, FPF(LD)). In addition, the relationship between, cohesion, RH, and aerosolization performance was drug specific. For example, an increase in RH between 15% and 75% resulted in increased cohesion and decreased FPF(LD) for SS and DSCG. In comparison, for TAA, a decrease in cohesion and increased FPF(LD) was observed when RH was increased (15-75%). Linear regression analysis comparing AFM with in vitro data indicated R(2) values > 0.80, for all data sets, suggesting the AFM could be used to indicate in vitro aerosolization performance.     

Latest advances in the development of dry powder inhalers

The current market for dry powder inhalers (DPIs) has over 20 devices in present use and at least another 30 under development. Clinicians recognize that DPIs are a suitable alternative to pressurized metered dose inhalers (pMDIs) for some patients but the relative performance of devices is often unclear. The problem is compounded by the need to reformulate pMDIs with new propellants, introducing further products to the market with associated variations in performance. This article reviews the DPIs currently available, the driving forces governing new designs, and the claimed advantages of DPIs in the development pipeline.     

In vitro-in vivo correlation study on nimesulide loaded hydroxypropylmethylcellulose microparticles

This study involves mathematical simulation model such as in vitro-in vivo correlation (IVIVC) development for various extended release formulations of nimesulide loaded hydroxypropylmethylcellulose (HPMC) microparticles (M1, M2 and M3 containing 1, 2, and 3 g HPMC, respectively and 1 g drug in each) having variable release characteristics. In vitro dissolution data of these formulations were correlated to their relevant in vivo absorption profiles followed by predictability worth analysis of these Level A IVIVC. Nimaran was used as control formulation to validate developed formulations and their respective models. The regression coefficients of IVIVC plots for M1, M2, M3 and Nimaran were 0.834 9, 0.831 2, 0.927 2 and 0.898 1, respectively. The internal prediction error for all formulations was within limits, i.e., < 10%. A good IVIVC was found for controlled release nimesulide loaded HPMC floating M3 microparticles. In other words, this mathematical simulation model is best fit for biowaiver studies which involves study parameters as those adopted for M3 because the value of its IVIVC regression coefficient is the closest to 1 as compared to M1 and M2.     

吸入粉雾剂的处方研究和制备工艺

吸入粉雾剂在治疗肺部疾病,如哮喘、慢性阻塞性肺病中应用广泛.文中广泛查阅欧盟、美国等国的吸入粉雾剂研发的要求,结合国内该剂型的研发和审批情况,对吸入粉雾剂的组成、处方筛选以及制备工艺进行详细的阐述.对吸入粉雾剂在处方筛选与制备过程中的影响因素加以详细讨论,为研发粉雾剂药学工作者提供有益的参考.     

Once-daily inhaled corticosteroids in children with asthma: dry powder inhalers

The cornerstone of pharmacological management of asthma in childhood is inhaled corticosteroids. These drugs are intended for long term treatment and, consequently, compliance is a major issue. Once-daily administration of maintenance medication would simplify treatment and it is likely that it would lead to better compliance. Moreover, the excellent safety profile of inhaled corticosteroid treatment tailored to disease severity may, theoretically, be further improved with once-daily administration. Studies comparing inhaled corticosteroids given once or twice daily to patients with asthma indicate that unstable asthma is best treated with at least 2 daily doses. On the other hand, it has been demonstrated that, if the asthma is stabilised, most children can be treated with inhaled corticosteroids once daily without loss of efficacy. Thus, the data suggest that newly diagnosed asthma, or asthma after deterioration, should first be reliably controlled with inhaled corticosteroids divided into at least 2 daily doses. Once-daily maintenance treatment should then be tried with the aim of improving compliance and quality of life. A dry powder inhalation device is probably the best choice for children from the age of 5 years.     

Equivalent lung deposition of budesonide in vivo: a comparison of dry powder inhalers using a pharmacokinetic method

AIMS: The aim of this study was to compare lung deposition of budesonide administered from two dry powder inhalers, Giona Easyhaler 200 microg/dose and Pulmicort Turbuhaler 200 microg/dose by utilizing a pharmacokinetic method. METHODS: This was an open, randomized, crossover study in 33 healthy subjects. The study consisted of four treatment periods separated by at least 4 wash-out days. Equivalence in lung deposition was assessed after a single inhaled 1000 microg (5 x 200 microg) dose of budesonide from Giona Easyhaler and from Pulmicort Turbuhaler. Concomitant oral charcoal administration (40 g) was used to prevent gastrointestinal (GI) absorption of budesonide. The efficacy of the charcoal was studied after oral administration of a budesonide 2 mg capsule. The subjects were trained to inhale the study drugs with controlled flow rates, which resulted in an equal pressure drop (4 kPa) across both inhalers. Venous blood samples for the determination of budesonide concentrations in plasma were drawn before and at predetermined time points up to 8 h after drug administration. Budesonide concentrations in plasma were determined using liquid chromatography-tandem mass spectrometry. Several pharmacokinetic parameters were estimated, the area under the budesonide concentration in plasma vs time curve from dosing to infinity (AUC(0, infinity)) being the primary response variable. Equivalence in lung deposition was concluded if the 90% confidence interval (CI) for the Easyhaler : Turbuhaler ratio of AUC(0, infinity) fell within the limits of 0.8-1.25. RESULTS: The mean AUC(0,infinity) value after Easyhaler treatment was 3.48 (standard deviation (SD) 0.93) ng ml(-1) h and after Turbuhaler treatment 3.46 (1.13) ng ml(-1) h. The Easyhaler : Turbuhaler AUC(0, infinity) ratio was 1.02 and the 90% CI was from 0.96 to 1.09. The mean C(max) values (SD) for budesonide in plasma after Easyhaler and Turbuhaler treatments were 1.22 (0.41) ng ml(-1) and 1.29 (0.44) ng ml(-1), respectively. There was no statistically significant difference (P = 0.39) between the median t(max) for Easyhaler (30 min) and Turbuhaler treatment (23 min). Charcoal impaired the GI absorption of budesonide by 96%. The occurrence of adverse events was similar during both treatments. CONCLUSIONS: The results show that the lung deposition of budesonide from Giona Easyhaler 200 microg/dose and Pulmicort Turbuhaler 200 microg/dose dry powder inhalers is equivalent. The charcoal block used to prevent GI absorption of swallowed budesonide was found to be effective.     

In vitro-in vivo correlation: perspectives on model development

In vitro-in vivo correlation (IVIVC) allows prediction of the in vivo performance of a drug based on the in vitro drug release profiles. To develop an effective IVIVC, the physicochemical and biopharmaceutical properties of the drug as well as the physiological environment in the body must be taken into consideration. Key factors include drug solubility, pK_a, drug permeability, octanol-water partition coefficient and pH of environment. In general, construction of an IVIVC involves three stages of mathematical manipulation: construct a functional relationship between input (in vitro dissolution) and output (in vivo dissolution); establish a structural relationship using data collected; parameterize the unknowns in the structural model. Some key mathematical relationships used in IVIVC development are presented. The establishment of an effective IVIVC has important implications in quality control and regulatory compliance.     

Alternative and generalized approach to in vitro-in vivo correlation

Evaluation of in vitro-in vivo correlation (IVIVC) plays important role in securing therapeutic effect if a dosage form undergoes technological modifications. Similarity (closeness) of dissolution profiles of the original and modified dosage forms has been traditionally considered to be sufficient for similar in vivo responses. This may be true if the IVIVC model (dependence between the dissolution and corresponding absorption profiles) is given by a linear straight line with the unit slope. The paper presents an alternative and generalized approach to IVIVC evaluation. Influences of pre-systemic processes (disintegration, dissolution, absorption) on the system response (concentration time profile C(t), bioavailability BD and other) are analyzed and evaluated. Both the magnitude and sign of IVIVC are then derived from the magnitudes and signs of these influences. The underlining idea is that pre-systemic processes do not correlate with the system response, (e.g., plasmatic concentration) if small modifications of the former do not induce significant changes of the later. If this is so, the therapeutic effects of the modified and original dosage forms may be considered equal or at least similar. In this way the problem of IVIVC is not only exactly mathematically founded but modifications of pre-systemic processes are directly projected to the system output-- the time profile of plasmatic concentration. Moreover, the approach is applicable to virtually any dosage form. Its feasibility was validated in vivo.     

Drug delivery characteristics of Bricanyl TurbohalerTM dry powder inhalers

The Turbohaler^TM is the one multidose reservoir type dry powder inhaler (DPI) with significant clinical usage but there is little information on the precision of its single dose delivery characteristics. The single dose delivery efficiency of terbutaline sulphate (nominally 500 μg) from two batches of Bricanyl Turbohalers^TM (11 and 59 devices) has therefore been studied at air flow rates of 28–30 and 60 1 min ⁻¹ which are clinically relevant test conditions for this DPI. At 60 1 min⁻¹ statistically significant differences both within and between batches were obtained for emitted dose (± SD, n = 110, 130), 421 ± 73, 387 ± 58μg and fine particle dose (0.5–6.4 μm MMAD), 249 ± 41, 214 ± 44μg. These data imply an emitted dose range of ± 50% and a fine particle dose range of ± 70% from this DPI system. Through-life total dose emission in terms of the average values remain consistent. Reducing air flow rates to approx. 30 1 min⁻¹ lowered the mean emitted dose by about one third with the clinically important fine particle dose being reduced 3-fold to 59 ± 25 μg; this underlines the likely sensitivity of effective delivery, to patients' lung function. These results reinforce the need to provide single dose data at clinically relevant flow rates in the assessment of DPI performance. Expressing data as mean performance for a cumulative series of dose units smooths down this single dose variability by a factor of two.     

Physiologically based approaches towards the prediction of pharmacokinetics: in vitro-in vivo extrapolation

In adapting to the challenge to make more informed selection of compounds for development, the pharmaceutical industry is increasingly embracing the application of mechanism-based models and prediction tools for prediction of pharmacokinetic parameters. This review first outlines the concepts and application of the major physiologically based prediction tools to extrapolate clearance, tissue distribution, and rate and extent of absorption from minimal in vitro or animal in vivo input data. Finally, the ability of these prediction tools, when placed within a generic whole body physiologically based model of pharmacokinetics, to predict plasma concentration-time profiles is briefly discussed.     

Application of spectrofluorometry for evaluation of dry powder inhalers in vitro

Andersen cascade impactor (ACI) is commonly used for the testing of pharmaceutical aerosols, which has to be coupled with an instrument for quantitative analysis of drug depositing on each stage of the ACI. This procedure consumes much time in operation. Therefore, this study was aimed at speeding up the process of drug analysis in aerosol formulations after obtaining samples from the ACI. From the results obtained, it was proved that the validated spectrofluorometric method was accurate and sensitive. It was capable of giving similar results to those we obtained from HPLC-UV analysis. There was no interference from the amount of lactose carrier incorporated in the formulation in the step of salbutamol analysis indicating specificity of the method. As a result, samples were analyzed without further separation. The detection limit was 0.1 microg/ml. Hence, spectrofluorometry can be used as a substitute method to HPLC-UV in determining the small quantity of salbutamol after aerosolization from dry powder aerosols. The present study suggests that spectrofluometry can be a rapid and efficient method in the pharmaceutical analysis of aerosols.     

气流速度对粉雾剂在呼吸道沉降的影响

目的 :研究吸入速度对不同粒径粉雾剂在呼吸道沉降的影响。方法 :以硫酸沙丁胺醇为模型药物 ,用双冲程试验仪评价不同的气流速度对吸入型粉雾剂在模拟肺部的沉降量。结果 :粒径为 5 4～ 10 0μm的重结晶乳糖为载体的硫酸沙丁胺醇混合型粉雾剂 ,增加吸入速度 ,提高药物在肺部的沉积量 ;而乳糖、甘露醇为载体 ,喷雾干燥法制备的粒径为 0 .5～ 6.5 μm粉雾剂 ,增加吸入速度 ,药物在肺部沉积量基本不变直至下降。结论 :物理混合型吸入剂随气流速度的增加 ,药物在肺部的沉降量增加。含载体喷干型吸入剂 (0 .5～ 6.5 μm)中的药物在肺部的沉降量取决于载体 (如甘露醇 )和吸入速度 (如 3 0 L· min-1 )。