Simon Warren

Comparison of in vitro and in vivo efficiencies of a novel unit-dose liquid aerosol generator and a pressurized metered dose inhaler

Gamma scintigraphic imaging was employed in 10 healthy volunteers to compare the total and regional lung deposition of aerosols generated by two delivery platforms that permitted microprocessor-controlled actuation at an optimal point during inhalation. An aqueous solution containing 99mTc-DTPA was used to assess the deposition of aerosols delivered by inhalation from two successive unit-dosage forms (44 microl volume) using a prototype of a novel liquid aerosol system (AERx Pulmonary Delivery System). This was compared with aerosol deposition after inhalation of two 50 microl puffs of a 99mTc-HMPAO-labeled solution formulation from a pressurized metered dose inhaler (MDI). The in vitro size characteristics of the radiolabeled aerosols were determined by cascade impaction. For the AERx system, the predicted lung delivery efficiency based on the product of emitted dose (60.8%, coefficient of variation (CV)=12%) and fine particle fraction (% by mass of aerosol particles <5.7 microm in diameter) was 53.3% (CV=13%). For the solution MDI, the emitted dose was 62.9% (CV=13%) and the predicted lung dose was 44. 9% (CV=15%). The AERx system demonstrated efficient and reproducible dosing characteristics in vivo. Of the dose loaded into the device, the mean percent reaching the lungs was 53.3% (CV=10%), with only 6. 9% located in the oropharynx/stomach. In contrast, the lung deposition from the solution MDI was significantly less (21.7%) and more variable (CV=31%), with 42.0% of the radiolabel detected in the oropharynx/stomach. Analysis of the regional deposition of the radioaerosol indicated a homogeneous pattern of deposition after delivery from the AERx system. A predominantly central pattern of distribution occurred after MDI delivery, where the pattern of deposition was biased towards a central zone depicting the conducting airways. The AERx system, in contrast to MDIs, seems highly suited to the delivery of systemically active agents via pulmonary administration.

Gamma scintigraphic evaluation of a novel budesonide dry powder inhaler using a validated radiolabeling technique

A scintigraphic study was carried out to compare the lung deposition of budesonide delivered via Clickhaler and Turbuhaler dry powder inhalers in healthy volunteers. Validation of Technetium-99m ((99m)Tc) radiolabeling of the budesonide/lactose blend used in the Clickhaler and excipient-free budesonide used in the Turbuhaler was carried out using a multistage liquid impinger, and compared with reference unlabeled devices. Budesonide was quantified using high-performance liquid chromatography and (99m)Tc by scintillation counting. The percentages (SD) of fine particles (<5.5 microm diameter) from radiolabeled and unlabeled devices were not significantly different (p > 0.05). Mean values for drug and radiolabel, respectively, were 34.6% (2.5) and 31.6% (3.8) for the Clickhaler, and 29.8% (5.5) and 31.4% (5 6) for the Turbuhaler. Fifteen healthy male volunteers received a single dose (2 x 200 microg actuations) from both devices in a double-blinded, double dummy, crossover study. During dosing, each inhalation maneuver was recorded using a computer-linked pressure transducer. To permit accurate determination of radiolabeled drug deposition, the lung margins of each volunteer were determined by Krypton-81m ((81m)Kr) gas imaging. Mean [SD] lung deposition for the Clickhaler (26.8% [6.8], RSD 25.2) was significantly greater (p < 0.001) than for the Turbuhaler (15.8% [6.6], RSD 42.2). Inspiratory flow rate parameters were similar for both devices with peak and mean values of 73 and 51 L/min for the Clickhaler, and 73 and 47 L/min for the Turbuhaler, respectively. These results indicate that, in healthy volunteers, budesonide lung deposition was higher and more consistent with the Clickhaler than with the Turbuhaler.

Mode of Breathing—Tidal or Slow and Deep—through the I-neb Adaptive Aerosol Delivery (AAD) System Affects Lung Deposition of 99mTc-DTPA

BACKGROUND The I-neb AAD System was designed to deliver aerosol with two different breathing pattern algorithms: the Tidal Breathing Mode (TBM) and the Target Inhalation Mode (TIM). For the purpose of the study, the TBM breathing pattern algorithm was set to guide the subjects to inhalation during tidal breathing with aerosol pulsed during 50-80% of the time spent on inhalation, whereas the TIM breathing pattern was set to guide the subject to a slow and deep inhalation of up to approximately 9 sec with aerosol pulsed for up to 7 sec, leaving 2 sec for particle deposition in the lungs. In TIM, the inspiratory flow was guided to approximately 20 L/min through a built-in resistance in the mouthpiece. METHODS We have, in a randomized, open-label, crossover study of 12 healthy subjects evaluated lung deposition following administration of a radiolabeled aerosol from the I-neb AAD System with the TBM and TIM breathing patterns. RESULTS The results showed that mean lung deposition was significantly higher when using the I-neb AAD System with the TIM breathing pattern (73.3%) than with the TBM breathing pattern (62.8%). The mean exhaled fractions were low (<1%) for both breathing patterns. The nebulization time was significantly shorter with the TIM breathing pattern (3.0 min) than with the TBM breathing pattern (4.7 min). CONCLUSIONS The results of the present study showed that lung deposition with the slow and deep inhalation achieved through the I-neb AAD System in TIM was superior to the lung deposition achieved during tidal breathing in TBM. With the combination of high lung deposition, almost no loss of aerosol during exhalation, and short nebulization time the I-neb AAD System with the TIM breathing pattern should be of special value to patients who require multiple daily dosing of aerosolized medication, are using drugs that should not be wasted into the room air, or would benefit from a more efficient delivery system.

The Synthesis and In Vitro Characterization of the Mucoadhesion and Swelling of Poly(Acrylic Acid) Hydrogels

The purpose of this research was to synthesize insoluble, mucoadhesive hydrogels by crosslinking linear poly(acrylic acid) with sucrose and investigate the relationship between hydrogel crosslink density, swelling, and in vitro mucoadhesion. A condensation reaction was employed to synthesize the hydrogels and crosslink density was varied by altering sucrose concentration and cure time. Equilibrium swelling at pH 7.4 was measured both gravimetrically and geometrically. In vitro mucoadhesion was determined by a tensile technique. Equilibrium swelling studies indicated that the crosslink density was proportional to both sucrose concentration and duration of cure time. In vitro mucoadhesive properties of the hydrogels improved as crosslink density increased. This was attributed to an increase in poly(acrylic acid) chain density/unit area of the equilibrium swollen hydrogel, which promoted interaction of the mucoadhesive and glycoprotein polymer chains.

Effect of Gender and Device Mouthpiece Shape on Bolus Insulin Aerosol Delivery Using the AERx Pulmonary Delivery System

AbstractPurpose. A study was designed to compare differences in insulin aerosol deposition profiles in healthy male and female subjects, as well as examine the effect of mouthpiece cross-sectional shape, volume, and taper on deposition profiles using a developmental AERx pulmonary delivery system. Methods. >Six mouthpieces were screened in the laboratory, and three were selected for clinical investigation: a cylindrical mouthpiece with constant-cross-sectional area, an elliptical mouthpiece with constant-cross-sectional area, and a tapered elliptical mouthpiece with an exit cross-sectional area equal to one half the entrance cross-sectional area. Results. There was no significant difference in the lung dose or in the deposition pattern between males and females (p > 0.05, by ANOVA). The cross-sectional shape of the mouthpiece had no significant effect on the clinical lung dose or the deposition pattern (p > 0.05, by ANOVA), although in vitrotesting showed lower emitted dose values with the tapered elliptical mouthpiece (by ANOVA and Duncans multiple range test, α = 0.05). Using the tapered mouthpiece in the clinic resulted in significantly more deposition on the mouthpiece itself when compared to the nontapered mouthpieces. Conclusion. Inhalation of insulin using the AERx system was insensitive to differences in male and female respiratory tract geometry across all mouthpiece designs examined.

Gamma scintigraphic pulmonary deposition study of glycopyrronium/formoterol metered dose inhaler formulated using co-suspension delivery technology

ABSTRACT This gamma scintigraphy imaging study was the first to assess pulmonary and extrathoracic deposition and regional lung deposition patterns of a radiolabelled long‐acting muscarinic antagonist/long‐acting &bgr;2‐agonist fixed‐dose combination glycopyrronium/formoterol fumarate dihydrate (GFF) 14.4/10 &mgr;g (equivalent to glycopyrrolate/formoterol fumarate 18/9.6 &mgr;g), delivered by pressurized metered dose inhaler (pMDI) using novel co‐suspension delivery technology. In this Phase I, randomized, single‐centre, single‐blind, single‐dose, two‐treatment, crossover, placebo‐controlled study (PT003020), 10 healthy male adults received two actuations of GFF pMDI (7.2/5.0 &mgr;g per actuation) and placebo pMDI (containing phospholipid‐based porous particles without active pharmaceutical ingredient), both radiolabelled with 99mTc, up to 5 MBq per actuation. Gamma scintigraphy images of lungs, stomach, head and neck were recorded. In addition, images of the actuators after use, collected mouth washings and exhalation filters were acquired. On average, 38.4% of the emitted dose of radiolabelled GFF pMDI, and 32.8% of radiolabelled placebo pMDI, was deposited in the lungs. The percentage emitted dose detected in the oropharyngeal and stomach regions was 61.4% and 66.9% for radiolabelled GFF pMDI and placebo pMDI, respectively. For both treatments, ≤0.25% of the emitted dose was detected in the exhalation filter. The normalized outer/inner ratio was 0.57 and 0.59 for radiolabelled GFF pMDI and placebo pMDI, respectively, and the standardized central/peripheral ratio was 1.85 and 1.94 respectively, indicating delivery of both co‐suspension delivery technology formulations throughout the airways. There were no new or unexpected safety findings. In conclusion, both formulations were efficiently and uniformly deposited in the lungs with similar regional deposition patterns, oropharyngeal and stomach deposition, exhalation fraction and actuator‐recovered dose. Graphical abstract Figure. No Caption available.