The onset and duration of the effects of morphine are similar after intravenous administration or inhalation via this new pulmonary drug delivery system. Morphine bioavailability after such administration is 59% of the dose loaded into the dosage form.
NIOV+O₂ yielded substantial exercise endurance improvements accompanied by respiratory muscle unloading and dyspnea reductions in patients with severe hypoxemic COPD.
Bioavailability of an aerosolized anti-inflammatory protein, soluble interleukin-4 receptor (IL-4R), was measured in patients with asthma using two different aerosol delivery systems, a prototype aerosol delivery system (AERx tethered model, Aradigm, Hayward, CA) and PARI LC STAR nebulizer (Pari, Richmond, VA). Regional distribution of the drug in the respiratory tract obtained by planar imaging using gamma camera scintigraphy was utilized to explain the differences in bioavailability. The drug, an experimental protein being developed for asthma, was mixed with radiolabel 99mTechnetium diethylene triaminepentaacetic acid (99mTc-DTPA). Aerosols were characterized in vitro using cascade impaction (mass median aerodynamic diameter [MMAD] and geometric standard deviation [GSD]); the AERx MMAD 2.0 microm (GSD 1.35), the PARI 3.5 microm (GSD 2.5). Four patients with asthma requiring maintenance aerosolized steroids were studied. First, regional volume was determined utilizing equilibrium 133Xe scanning. Then, after a brief period of instruction, patients inhaled four breaths of protein using AERx (0.45 mg in total) followed 1 week later by inhalation via PARI (3.0 mg nebulized until dry). Each deposition image was followed by a measurement of regional perfusion using injected 99mTc albumin macroaggregates. Deposition of 99mTc-DTPA in the subjects was determined by mass balance. Regional analysis was performed using computerized regions of interest. The regional distribution of deposited drug was normalized for regional volume and perfusion. Following each single inhalation, serial blood samples were drawn over a 7-day period to determine area under the curve (AUC) of protein concentration in the blood. Median AUC(AERx)/AUC(PARI) was 7.66/1, based on the amount of drug placed in each device, indicating that AERx was 7.66 times more efficient than PARI. When normalized for total lung deposition (AUC per mg deposited) the ratio decreased to 2.44, indicating that efficiencies of the drug delivery system and deposition were major factors. When normalized for sC/P and (pU/L)xe ratios (central to peripheral and upper to lower ratios are parameters of regional distribution of deposited particles and regional per- fusion ['p']), AUC(AER)x/AUC(PARI) further decreased to 1.35, demonstrating that peripheral sites of deposition with the AERx affected the final blood concentration of the drug. We conclude that inhaled bioavailability of aerosolized protein, as expressed by AUC, is a quantifiable function of lung dose and regional deposition as defined by planar scintigraphy.
This was a preliminary feasibility study to assess the pharmacokinetics and acute safety of a single dose of orally inhaled testosterone via the AERx system, a novel handheld aerosol delivery system in postmenopausal women. Twelve postmenopausal women stabilized on oral estrogen therapy were treated with a single dose of testosterone (0.1, 0.2, or 0.3 mg) by inhalation. Plasma concentrations of sex steroids were measured between 1 and 360 minutes. Pulmonary and cardiovascular adverse events were monitored. Inhaled testosterone produced a dose-dependent increase in plasma total and free testosterone. At the highest dose (0.3 mg), total and free testosterone increased from baseline (mean +/- SD, 0.6 +/- 0.3 nmol/L, 2.5 +/- 1.0 pmol/L) to maximum levels of 62.6 +/- 20.4 nmol/L (total) and 168.2 +/- 50.2 pmol/L(free), occurring 1 to 2 minutes after dosing. A 2-compartment model best described the free and total testosterone pharmacokinetic profile. Dihydrotestosterone levels were higher than baseline at 60 minutes (P < .0002). Estradiol did not vary, but sex hormone binding globulin and albumin fell. There were no adverse events related to the treatment. Administration of inhaled testosterone is safe and achieves a supraphysiologic "pulse" kinetic profile of total and free testosterone with a rapid return to pretreatment levels.
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