Relative lung and systemic bioavailability of sodium cromoglycate inhaled products using urinary drug excretion post inhalation

A review of the in vitro and in vivo valved holding chamber (VHC) literature with a focus on the AeroChamber Plus Flow-Vu Anti-static VHC

Valved holding chambers (VHCs) reduce the need for inhalation-actuation coordination with pressurized metered dose inhalers (pMDIs), reduce oropharyngeal drug deposition and may improve lung deposition and clinical outcomes compared to pMDIs used alone. While VHCs are thus widely advocated for use in vulnerable patient groups within clinical and regulatory guidelines, there is less consensus as to whether the performance differences between different VHCs have clinical implications. This review evaluates the VHC literature, in particular the data pertaining to large- versus small-volume chambers, aerosol performance with a VHC adjunct versus a pMDI alone, charge dissipative/conducting versus non-conducting VHCs, and facemasks, to ascertain whether potentially meaningful differences between VHCs exist. Inconsistencies in the literature are examined and explained, and relationships between in vitro and in vivo data are discussed. A particular focus of this review is the AeroChamber Plus® Flow-Vu® Anti-static VHC, the most recent iteration of the AeroChamber VHC family.

Urinary pharmacokinetic methodology to determine the relative lung bioavailability of inhaled beclometasone dipropionate

AIM

Urinary pharmacokinetic methods have been identified to determine the relative lung and systemic bioavailability after an inhalation. We have extended this methodology to inhaled beclometasone dipropionate (BDP).

METHOD

Ethics Committee approval was obtained and all subjects gave consent. Twelve healthy volunteers received randomized doses, separated by >7 days, of 2000 µg BDP solution with (OralC) and without (Oral) 5 g oral charcoal, 10,100 µg inhalations from a Qvar(®) Easibreathe metered dose inhaler (pMDI) with (QvarC) and without (Qvar) oral charcoal and eight 250 µg inhalations from a Clenil(®) pMDI (Clenil). Subjects provided urine samples at 0, 0.5, 1, 2, 3, 5, 8, 12 and 24 h post study dose. Urinary concentrations of BDP and its metabolites, beclometasone-17-monopropionate (17-BMP) and beclometasone (BOH) were measured.

RESULTS

No BDP, 17-BMP or BOH were detected in any samples post OralC dosing. Post oral dosing no BDP was detected in all urine samples and no 17-BMP or BOH was excreted in the first 30 min. Significantly more (P < 0.001) BDP, 17-BMP and BOH were excreted in the first 30 min and the cumulative 24 h urinary excretions post Qvar and Clenil compared with Oral. The mean ratio (90% confidence interval) of the 30 min urinary excretions for Qvar compared with Clenil was 231.4 (209.6, 255.7) %.

CONCLUSION

The urinary pharmacokinetic methodology to determine the relative lung and systemic bioavailability post inhalation, using 30 min and cumulative 24 h post inhalation samples, applies to BDP. The ratio between Qvar and Clenil is consistent with related clinical and lung deposition studies.

Have inadequate delivery systems hampered the clinical success of inhaled disodium cromoglycate? Time for reconsideration

IMPORTANCE OF THE FIELD

Disodium cromoglycate (DSCG) fits with the perception of a safe drug, but conclusions from questionable meta-analyses reduced its use. In addition, drug delivery aspects, such as hygroscopicity and the poor performance of delivery systems, were not considered to be important determinants of therapeutic failures.

AREAS COVERED IN THIS REVIEW

Drug delivery aspects and parameters affecting lung deposition and distribution, important parameters for therapeutic efficacy, are addressed. In addition, the distribution and ratio of mast cell tryptase and chymase-positive phenotypes in the lungs and their role in the prostaglandin and leukotriene pathway are discussed.

WHAT THE READER WILL GAIN

Information on why in vitro data are an excellent tool to understand better therapeutic failures associated with the moisture sensitivity of DSCG and the difficulty in handling and operating DSCG delivery systems in a therapeutically reliable way.

TAKE HOME MESSAGE

Pharmacological efficacy of DSCG has been demonstrated in animals and humans. If the drug is delivered to the site of inflammation in an effective dose, a reliable therapeutic effect can be expected. DSCG has extra properties and potential unspecific antiviral properties and may offer new therapeutic treatment aspects for asthma and viral-induced bronchiolitis in early childhood.

Assessment methods of inhaled aerosols: technical aspects and applications

The pulmonary route has been used with success for the treatment of both lung (asthma) and systemic diseases (diabetes). The fate of an inhaled drug (absorption and deposition) within human lungs has great importance, particularly in drug development and quality control. This article focuses on the various methods that are now applied for aerosol fate investigation. Several assessment methods, ranging from in vitro assays (impaction and optical systems) to in vivo experiments (imaging and pharmacological methods), are described. In vitro assays measure particle size distribution and emitted drug dose, which could be predictive of lung deposition pattern in vivo. However, in vivo methods provide direct information about the concentration and the location of inhaled drug within lung. Advantages and limitations of the different techniques are identified. In addition to these experimental techniques, mathematical deposition models, elaborated in more realistic conditions and designed to predict the fate of inhaled particles, are also illustrated.

Lung Deposition after Electronically Breath-Controlled Inhalation and Manually Triggered Conventional Inhalation in Cystic Fibrosis Patients

The present work aimed to investigate whether lung deposition can be improved by using a device that optimizes the breathing pattern through electronic control. The relative lung deposition was estimated by inhalation of the marker substance, sodium cromoglycate (SCG), and measurement of urinary excretion of SCG. Thirteen cystic fibrosis (CF) patients (aged 8-20 years) received 20 mg of SCG as nebulizer solution by means of (a) conventional inhalation (Parimaster + Pari LC Star nebulizer, manual interrupter) and (b) electronically breath-controlled inhalation (AKITA + Pari LC Star nebulizer). Inhalations were trained and supervised by a physiotherapist. Patients were asked to provide answers to a questionnaire about the convenience of electronically breath-controlled inhalation. Urine was collected in five fractions until 12 h p.a., and the excreted SCG was determined by means of high-performance liquid chromatography (HPLC). Following breath-controlled inhalation, the amount of SCG excreted in urine was significantly greater than after conventional inhalation (2.22 +/- 0.61 mg vs. 1.63 +/- 0.59 mg, p < 0.001). The absorption half-life for SCG following breath-controlled inhalation was significantly shorter when compared with conventional inhalation (78 +/- 23 min vs. 107 +/- 29 min; p < 0.01), suggestive of a more peripheral deposition for the former. Ninety-two percent of the patients judged that the electronically breath-controlled inhalation was good or very good. In conclusion, inhalation with an electronically optimized breathing pattern yields a greater and more peripheral lung deposition of SCG compared with the manually triggered conventional nebulizer technique in CF patients with several years of aerosol inhalation experience.

Risk of high blood pressure in salt workers working near salt milling plants: a cross-sectional and interventional study

BACKGROUND

Workers working close to salt milling plants may inhale salt particles floating in the air, leading to a rise in plasma sodium, which, in turn, may increase the blood pressure and the risk of hypertension.

METHODS

To test the above hypothesis, occupational health check-up camps were organized near salt manufacturing units and all workers were invited for a free health examination. The workers who worked with dry salt in the vicinity of salt milling plants were defined as "non-brine workers," while those working in brine pans located far away from milling plants were defined as "brine workers." Blood pressure (BP) was measured during each clinical examination. In all, 474 non-brine workers and 284 brine workers were studied.

RESULTS

Mean systolic blood pressure of non-brine workers (122.1 +/- 13.3 mm Hg) was significantly higher than that of brine workers (118.8 +/- 12.8 mm Hg, p < 0.01). Mean diastolic blood pressure of non-brine workers (71.5 +/- 10.4 mm Hg) was significantly higher than that of brine workers (69.7 +/- 9.4 mm Hg, p = 0.02). The prevalence of hypertension was significantly higher in non-brine workers (12.2%) than in brine workers (7.0%, p = 0.02). Nineteen salt workers were monitored while they used face masks and spectacles, for six days. Systolic, as well as diastolic, blood pressure of these workers began declining on the third day and continued to decline on the fourth day, but remained stationary up to the sixth day. The concentration of salt particles in the breathing zone of these workers was 376 mg/m3 air.

CONCLUSION

Inhalation of salt particles in non-brine workers may be an occupational cause of increased blood pressure.

Does wearing a noseclip during inhalation improve lung deposition?

Using nebulization, only a small proportion of the dose reaches the lungs, while the remainder is swallowed, exhaled into the atmosphere, or remains in the nebulizer. It was the purpose of this study to investigate whether wearing a noseclip during inhalation can improve lung deposition. Relative lung deposition was compared by inhalation of the marker substance, sodium cromoglycate (SCG), and measurement of urinary excretion of SCG. The SCG absorption half-life allows one to differentiate indirectly between a more or less peripheral deposition. Ten CF patients (9-18 years old) inhaled, under routine conditions, a solution containing 20 mg of SCG in a randomized crossover design through a mouthpiece, without and with a noseclip being worn. Following inhalation without and with a noseclip, no statistically significant difference was seen in the amount of SCG excreted in urine (0.9 +/- 0.4 mg vs. 1.0 +/- 0.5 mg; p = 0.402) and absorption half-life (93 +/- 25 min vs. 113 +/- 36 min; p = 0.083). In conclusion, wearing a noseclip during inhalation under conditions relevant to practice does not increase the amount deposited into the lungs of CF patients and, also, there has been no indication of a more peripheral lung deposition.

Lung deposition in cystic fibrosis patients using an ultrasonic or a jet nebulizer

This study was conducted to compare pulmonary deposition following inhalation with an ultrasonic and a jet nebulizer in CF patients under conditions relevant to practice. The marker substance used to estimate the relative lung bioavailability was sodium cromoglycate (SCG), which is poorly absorbed from the gastrointestinal tract, but is completely absorbed from the lungs. Ten CF patients (aged 9-21 years) used an ultrasonic nebulizer (Multisonic compact 2.4 MHz) and a jet nebulizer (Parimaster, LC Plus Turbo) in a crossover design to inhale a solution containing 20 mg of SCG and a beta(2)-agonist. Urine was collected in five fractions until 12 h p. a., and the excreted SCG was determined by means of HPLC. Prior to each inhalation, the patients' pulmonary function was measured employing a Pneumoscope. Using the ultrasonic nebulizer, the amount of SCG excreted in urine was significantly greater than that after inhalation with the jet nebulizer (1.43 +/- 0.47 mg vs. 1.04 +/- 0.47 mg; p = 0.002), despite the larger residual volume in the ultrasonic nebulizer. The absorption half-life for SCG following ultrasonic nebulization was significantly shorter when compared with jet nebulization (84 +/- 14 min vs. 101 +/- 19 min; p = 0.005), being suggestive of a more peripheral deposition. Furthermore, an inverse relationship was found between absorption half-life and FEV(1) (% pred.) (r = -0.655, p = 0.04) or MMEF(75/25) (% pred.) (r = -0.844, p = 0.031), but only with the ultrasonic nebulizer. In conclusion, the ultrasonic nebulizer tested when used for inhalation in CF patients was found to be at least equivalent to the jet nebulizer.