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PubMed1998

Concomitant inhaled corticosteroid resensitises cardiac beta2-adrenoceptors in the presence of long-acting beta2-agonist therapy.

OBJECTIVE: The aim of the present study was to evaluate the effects of concomitant inhaled corticosteroid therapy on the sensitivity of cardiac beta2-adrenoceptors in patients receiving regular long-acting beta2-agonists. METHODS: Twelve healthy subjects (6 female), mean age 29 years, were randomised in a double-blind cross-over study to receive either inhaled placebo or inhaled budesonide 1.2 mg twice daily, each for 7 days, with a minimum of 7 days washout period between the two treatments. Patients also received concomitant treatment with inhaled eformoterol 24 microg twice daily during each of the 2 treatment periods. The patients attended the laboratory during both treatment periods at 0730 hours, when a dose-response curve for systemic beta2-adrenoceptor responses to inhaled salbutamol (0.8-3.2 mg) was constructed before and after completing 7 days of each treatment. Early morning (0800 hours) plasma cortisol was also evaluated as a marker of systemic glucocorticoid activity. RESULTS: There was a significant fall in 0800 hours plasma cortisol induced by budesonide comparing pre- and post-values (407 vs 322 nmol.1(-1), but not with placebo. There were no differences in the response to salbutamol prior to treatment when comparing eformoterol with placebo versus eformoterol with budesonide. Comparing before and after within-treatment heart rate response, there was a significant reduction in peak salbutamol response with eformoterol and placebo, which was partially reversed by eformoterol and budesonide. For between-treatment comparisons after eformoterol treatment, the heart rate was significantly higher in the presence of budesonide in comparison with placebo for peak salbutamol response (change from baseline), i.e. 24.2 vs 34.7 beats min(-l). There was, however, no significant difference in the peak delta potassium response to salbutamol after eformoterol treatment when comparing budesonide with placebo (-0.39 vs -0.48 mmol.1(-1)). CONCLUSION: Concomitant therapy with inhaled budesonide resensitised the cardiac beta2-adrenoceptor response to salbutamol in subjects who were receiving regular twice-daily eformoterol. This may be of clinical relevance in terms of the propensity for systemic beta2-mediated adverse effects with repeated puffs of salbutamol, which might conceivably occur in the setting of acute asthma.

Administration, Inhalation↗
PubMed2002

Hyperbaric oxygen increases the lung's susceptibility to inhaled lipopolysaccharide in mice.

Hyperbaric oxygen (HBO2) has been shown to inhibit the adhesion function of beta(2)-integrin, which is important in mediating cell-to-cell adhesion and extravasation of inflammatory cells. In the present study, we examined the effects of HBO2 exposure on neutrophil infiltration and tissue injury in a model of acute lung inflammation induced by lipopolysaccharide (LPS) inhalation. Male C57BL/6 mice of 8 weeks old were exposed to 3 atmosphere absolute (ATA) 100% HBO2, 3 ATA hyperbaric air (HBA), or room air for 90 min. After exposure, they were exposed to aerosolized LPS solution (1 mg/ml) or saline in a plexiglass chamber for 10 min. Four hours after inhalation, bronchoalveolar lavage (BAL) was performed to determine protein concentration, LDH activity, total cells, and differential cell counts in the lavage fluid (BALF). Myeloperoxidase (MPO) content, lung histopathology, and plasma nitric oxide (NO) metabolite concentrations were also determined in separate sets of animals. We observed that LPS inhalation increased neutrophil number in the BALF, which was significantly inhibited by HBO2 but not HBA pre-exposure. However, MPO content in the lung was prominently increased by HBO2 pre-exposure, which correlated with increased PMN infiltration in lung tissues. Further, HBO2 plus LPS, but not saline inhalation caused a significant increase in the BALF protein level and LDH activity compared with that of LPS inhalation alone. LPS exposure induced significant increase in plasma NO metabolites, which was not potentiated by HBO2 pre-exposure. The inducible nitric oxide synthase inhibitor, aminoguanidine, significantly attenuated the increases in plasma NO metabolites and tissue MPO content as well as lung injuries. In summary, our data suggest that HBO2 pre-exposure increases the lung's susceptibility to inhaled LPS, which may be related to increased tissue neutrophil infiltration and dependent on interaction(s) between HBO2 exposure with LPS-induced nitric oxide production.

Administration, Inhalation↗
PubMed1997

Inhaled versus systemic steroids in chronic oxygen dependency of preterm infants.

UNLABELLED: The speed of action and side-effects of systemic verus inhaled steroids was compared in infants with mild-moderate oxygen dependency. Forty infants (median gestational age 27 weeks) were randomized to receive either 10 days of dexamethasone (systemic group) or budesonide (100 micrograms qds) (inhaled group). At randomization, there was no significant difference in the gestational or postnatal age, inspired oxygen requirements or compliance of the respiratory system of the two groups. After 36 h of treatment, there were significant changes (P < 0.01) in both the inspired oxygen concentration and compliance of the respiratory system in the systemic but not the inhaled group. Only after 1 week of inhaled therapy were improvements in respiratory status noted but, even at that time, the inspired oxygen requirement was significantly lower in the systemic versus the inhaled group. In the systemic group only, however, were there significant increases in blood pressure. CONCLUSION: Systemically administered rather than inhaled steroids appear to have a faster onset of action.

Administration, Inhalation↗
PubMed2005

Influence of air flow on the performance of a dry powder inhaler using computational and experimental analyses.

PURPOSE: The aims of the study are to analyze the influence of air flow on the overall performance of a dry powder inhaler (Aerolizer and to provide an initial quantification of the flow turbulence levels and particle impaction velocities that maximized the inhaler dispersion performance. METHODS: Computational fluid dynamics (CFD) analysis of the flow field in the Aerolizer, in conjunction with experimental dispersions of mannitol powder using a multistage liquid impinger, was used to determine how the inhaler dispersion performance varied as the device flow rate was increased. RESULTS: Both the powder dispersion and throat deposition were increased with air flow. The capsule retention was decreased with flow, whereas the device retention first increased then decreased with flow. The optimal inhaler performance was found at 65 l min(-1) showing a high fine particle fraction (FPF) of 63 wt.% with low throat deposition (9.0 wt.%) and capsule retention (4.3 wt.%). Computational fluid dynamics analysis showed that at the critical flow rate of 65 l min(-1), the volume-averaged integral scale strain rate (ISSR) was 5,400 s(-1), and the average particle impaction velocities were 12.7 and 19.0 m s(-1) at the inhaler base and grid, respectively. Correlations between the device flow rate and (a) the amount of throat deposition and (b) the capsule emptying times were also developed. CONCLUSIONS: The use of CFD has provided further insight into the effect of air flow on the performance of the Aerolizer. The approach of using CFD coupled with powder dispersion is readily applicable to other dry powder inhalers (DPIs) to help better understand their performance optimization.

Administration, Inhalation↗
PubMed1996

Inhalation of nitric oxide after lung transplantation.

BACKGROUND: Pulmonary hypertension is a postoperative complication that may adversely affect the outcome of lung transplantation. The effect of nitric oxide (NO) inhalation on pulmonary hemodynamic indices after lung transplantation was studied and compared with findings in control pigs. METHODS: Varying concentrations of NO were inhaled by 5 pigs after left lung transplantation and right pneumonectomy and by 5 controls after right pneumonectomy at an inspired oxygen fraction of 0.21 and 0.5. Hemodynamic data were recorded continuously, and fast circulatory courses were analyzed. RESULTS: Inhalation of NO reduced pulmonary vascular resistance and mean pulmonary arterial pressure in all pigs, but the decrease was pronounced and dose dependent only at an inspired oxygen fraction of 0.21 in the pigs that had transplantation. These were the only pigs that became hypoxic. With the termination of NO, there was a dose-independent rebound pulmonary vasoconstriction in the controls, especially at an inspired oxygen fraction of 0.21, but not in the pigs that had transplantation. This response was transient and could be blunted with a higher inspired oxygen fraction. CONCLUSION: Inhalation of NO reduced pulmonary vascular resistance in the transplanted lung and may be useful in the treatment of pulmonary hypertension after lung transplantation. The rebound pulmonary vasoconstriction with the termination of NO inhalation stresses the need to be aware of this effect and to wean NO carefully in clinical situations. This study showed oxygen dependency, which has to be taken into consideration in dose-response studies involving NO inhalation.

Administration, Inhalation↗
PubMed1994

Predicting ventilation failure in children with inhalation injury.

Despite advances in mechanical ventilatory support for patients with smoke inhalation injury, including the use of high-frequency flow-interruption ventilators such as the VDR, inhalation injury alone may increase mortality by as much as 20% in patients with thermal injury, and up to 60% when pneumonia occurs. Inhalation injury causes a primary large and small airway epithelial insult that results in ventilation abnormalities, rather than a primary alveolar lesion that results in oxygenation abnormalities as occur in multiple-system organ failure. Patients with inhalation injury requiring high ventilatory pressures experience complications of barotrauma and frequently succumb to necrotizing tracheobronchitis and oxygenation abnormalities after 2 to 4 weeks of mechanical ventilation. Ventilatory indexes obtained early in the postburn period allow the development of accurate predictive formulae that identify patients who will not be adequately supported by mechanical ventilation after smoke inhalation injury. Early identification of such patients will allow rapid conversion to other methods of ventilatory support that effect gas exchange, with minimal risk of further barotrauma, while inhalation injury healing occurs. Such predictors may be developed for other disease processes that are characterized by severe pulmonary ventilatory dysfunction.

Adolescent↗
PubMed1996

Nitrous oxide inhalation: effects on maternal and fetal circulations at term.

OBJECTIVE: To evaluate the hemodynamic effects of nitrous oxide inhalation in normal term pregnancy. METHODS: Twenty healthy term pregnant women were given 30% nitrous oxide in pure oxygen for 2 minutes, and the hemodynamics were assessed by pulsed-wave color Doppler velocimetry of the uterine and internal carotid artery of the mother and the umbilical and middle cerebral artery of the fetus. Each vessel was assessed separately, allowing a 5-minute wash-out period between the inhalations. The measurements were continued for 2 minutes after the inhalation, and the pulsatility index (PI) was determined at 1-minute intervals. The maternal heart rate and blood pressure (BP) were recorded before and after inhalation; fetal well-being was confirmed with cardiotocography. Analysis of variance for repeated measurements and paired-sample t test were used for statistical analysis. RESULTS: A significant decrease in the PI of the maternal internal carotid artery was observed after 2-minutes of inhalation (from 0.83 +/- 0.22 to 0.71 +/- 0.20; P < .001). The uterine artery PI and maternal BP and heart rate were not affected by nitrous oxide. A significant decrease was evident even in the fetal middle cerebral artery PI (from 1.37 +/- 0.27 to 1.22 +/- 0.17; P = .02). The umbilical artery PI remained unchanged. CONCLUSION: Both maternal and fetal central vascular resistance were decreased by 30% nitrous oxide inhalation. So far, no adverse effects to mother or fetus have been demonstrated in clinical practice. However, preterm fetuses are susceptible to intracranial hemorrhage, and the cerebral hyperemia by nitrous oxide might increase the risk of hemorrhage in these fetuses. This hypothesis requires further investigation.

Adult↗
PubMed1994

Effects of inhaled nitric oxide in rats with chemically induced pulmonary hypertension.

To determine the model animal with pulmonary hypertension in which nitric oxide (NO) inhalation reduces pulmonary arterial pressure (PAP), we examined the inhalation of 20-100 ppm NO gas on normal rats and rats with monocrotaline induced pulmonary hypertension. In the control group, mean PAP showed no change after spontaneous breathing of NO at the concentration of 20 to 100 ppm for 5 min. On the contrary, in both the severe (mean PAP > 40 mmHg) and moderate (mean PAP < 40 mmHg) pulmonary hypertensive groups, NO inhalation produced a prompt reduction of the mean PAP which had been elevated by monocrotaline. 20 ppm NO inhalation reduced mean PAP from 64.4 +/- 3.7 mmHg to 56.2 +/- 4.4 mmHg (mean +/- SEM, P < 0.01) in the severe pulmonary hypertensive group, from 31.0 +/- 2.0 mmHg to 24.2 +/- 0.9 mmHg in the moderate pulmonary hypertensive group (mean +/- SEM, P < 0.05). The onset of the reduction of mean PAP occurred within 30 sec after the start of NO inhalation and maximum reduction occurred within 4 min. 20 ppm NO inhalation significantly reduced mean PAP, and mean PAP was reduced dose-dependently at the concentration of 20 to 60 ppm and reaction to NO was almost constant at the concentrations of over 60 ppm.

Administration, Inhalation↗
PubMed1987

The fate of isoprene inhaled by rats: comparison to butadiene.

Isoprene (2-methyl-1,3-butadiene), a volatile monomer occurring in the natural environment and used in the manufacture of elastomers, is a close chemical relative of the animal carcinogen 1,3-butadiene. To obtain toxicokinetic data for inhaled isoprene, male F344 rats were exposed in groups of 30 to 14C-labeled isoprene vapor at four concentrations from 8 to 8200 ppm. The percentage of the inhaled isoprene that was metabolized decreased with increasing exposure concentration. The percentage of the total metabolites (that is, non-isoprene-retained 14C) excreted in urine and feces or expired was determined as a function of vapor concentration. About 75% of the total metabolites was excreted in urine. This was independent of inhaled isoprene concentration. After exposure to 8200 ppm, a larger percentage of the metabolites was excreted in feces than after exposure to lower concentrations. Using vacuum line techniques, blood metabolite concentrations were determined as functions of both vapor concentration and exposure duration. At one exposure concentration (1480 ppm) metabolites were measured in the nose, lungs, liver, kidney, and fat, as well as in blood. A mutagenic metabolite, isoprene diepoxide, was tentatively identified in all tissues examined. Between 0.0018 and 0.031% of the inhaled 14C label was tentatively identified as this metabolite in blood. The relative amount of the metabolites present in blood was highest for low concentrations of inhaled isoprene and for shorter exposure durations. Body fat appeared to be a reservoir for both isoprene metabolites and isoprene itself. The appearance of metabolites in the respiratory tract after short exposure durations together with low blood concentrations of isoprene indicated that substantial metabolism of inhaled isoprene in the respiratory tract may occur.

Administration, Inhalation↗
PubMed1989

The fate of inhaled octane and the nephrotoxicant, isooctane, in rats.

To determine if inhaled nephrotoxic branched and nonnephrotoxic straight chain alkanes differ substantially in their biological fate, male F344 rats were exposed to 14C-labeled isooctane and octane vapors at approximately 1 and 350 ppm by the nose-only mode for 2 hr. Radioactivity in exhalant, urine, and feces was determined for 70 hr post exposure, after which residual radioactivity in the rat carcasses was determined. Absorbed [14C]isooctane equivalents were eliminated almost exclusively via the kidneys, while absorbed [14C]octane equivalents were excreted about equally via the kidneys and as 14CO2. Kidney excretion of isooctane-introduced 14C was protracted over the entire 70 hr postexposure observation period whereas for octane-introduced 14C, kidney excretion was essentially complete after 10-20 hr. About 5% of the [14C]octane equivalents inhaled at 1 ppm remained in the carcass 70 hr after inhalation exposure. Two percent of the [14C]octane equivalents inhaled at 350 ppm and 1-2% of the [14C]isooctane equivalents inhaled at either 1 or 350 ppm remained in the carcass 70 hr after inhalation exposure. The different patterns of excretion of metabolites of isooctane compared to octane may be a factor affecting the differences in nephrotoxicity between these two compounds.

Acute Kidney Injury↗
PubMed1991

Sites for uptake of inhaled vapors in beagle dogs.

The site of uptake of inhaled vapors profoundly influences which respiratory tract tissues receive the highest doses. How the site of uptake depends on the physicochemical properties of inhaled vapors has been the subject of experiment and speculation for decades, but remains undefined. Using techniques that distinguish between vapor uptake in the nose and lung during cyclic breathing by Beagle dogs, we examined uptake of the vapors of 2,4-dimethypentane (DMP), propyl ether, butanone, dioxolane, and ethanol. These compounds have blood/air partition coefficients ranging from 1 to 2000. The effect of altering respiratory rates on vapor uptake was examined for DMP and dioxolane vapors. Deposition of vapors in the nasal cavity during inhalation was highly dependent on the partition coefficient. Vapor deposited in the nasal mucosa during inhalation was desorbed to a substantial extent during exhalation. Lung uptake of total inhaled vapor was limited by the amount available after passage through the nose, but in no case did it exceed 50% of the available amount. The data suggest that the diffusion of vapor molecules through the tissue barrier separating the air/tissue interface from the tissue/blood interface constitutes a significant resistance for both nasal uptake and lung uptake of many inhaled vapors. The data were used to validate a mathematical model describing nasal uptake of vapors. The model is described in the companion paper.

Administration, Inhalation↗
PubMed1989

Lung injury induced by short-term intermittent trimellitic anhydride (TMA) inhalation.

We have developed a rat model of lung injury with interstitial pneumonitis, lung hemorrhage, and a systemic and pulmonary immune response to trimellitic anhydride (TMA)-haptenized proteins induced by TMA inhalation for 10 days. The present studies explored the induction of lung injury induced by short-term intermittent TMA inhalation, a model more likely to simulate short-term industrial exposures during inadvertent spills of TMA. Sprague-Dawley rats inhaled TMA powder (500 micrograms/m3) on days 1, 5, and 10, and were necropsied on day 30, 18 hours after a 6-hour TMA-inhalation challenge on day 29. Rats were bled every second day and at necropsy. Serum IgG, IgA, and IgM antibody to trimellityl rat serum albumin was measured by ELISA. There was a rise in IgM and IgA antibody to trimellityl rat serum albumin starting at day 5 that peaked at day 20 with a decline in IgM by day 30. IgG antibody rose at day 7, peaked at day 20, and plateaued. The IgG antibody level was 10 times higher than the IgA or IgM level. In a second experiment, 18 rats were administered TMA-inhalation exposure on days 1, 5, and 10, and a TMA challenge on day 22. The number of hemorrhagic foci, lung weights, and lung-displacement volumes at necropsy on day 23 were highly correlated with IgG, IgA, and IgM serum-antibody levels. In a final experiment, rats developed a mean of 112 hemorrhagic foci per lung on day 30 after receiving only two TMA-inhalation exposures on days 1 and 5 with a rechallenge on day 29. (ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1990

A study of the mechanism of the antiasthmatic action of inhaled budesonide.

Inhaled antiasthmatic steroids have been assumed and yet never proved to exert their antiasthmatic effect by topical action in the airways. We tested the hypothesis that the efficacy of inhaled budesonide (BUD) might be due instead to its systemic activity after absorption. We compared inhaled and oral BUD with doses selected to ensure higher peak plasma levels and a greater area under the plasma concentration curve with the oral treatment. After pretreatment with beclomethasone to maximize asthma control, 47 adults with asthma were randomized to receive 0.4 mg of inhaled BUD per day (n = 16) or 1.4 mg of oral BUD per day (n = 15), or placebo (n = 16) in double-blind fashion and then followed weekly until asthma relapsed or for 8 weeks if no relapse occurred. "Relapse" was defined as a drop in the mean peak expiratory flow rate greater than 2 SEM below the mean during the baseline week before switching to the test drugs. The time to relapse was the primary outcome variable. Time to relapse was longer with inhaled than with oral BUD (medians, 22 versus 7.9 days; p = 0.003) or placebo (medians, 22 versus 9 days; p = 0.004). Oral BUD and placebo did not differ (p = 0.41). The morning serum cortisol levels remained normal during all three treatments. Thus, at conventional dosage the antiasthmatic effect of inhaled BUD may be fully explained by a local intrapulmonary action.

Administration, Inhalation↗
PubMed1990

Effect of inhaled furosemide on the bronchial response to methacholine and cold-air hyperventilation challenges.

Inhaled furosemide has been recently demonstrated to inhibit the bronchoconstrictive effects of exercise, ultrasonically nebulized distilled water, and antigen challenge. The presumed mechanism of action of these challenges is through mast cell degranulation. We report on the effect of inhaled furosemide on cold-air hyperventilation challenge (CAHC) and methacholine challenge. We studied 10 subjects with mild to moderate asthma in a double-blind, placebo-controlled, crossover study. Inhaled furosemide did not affect FEV1 in the hour after inhalation, and there was no significant difference between placebo or furosemide on the dose of methacholine causing a 20% fall in FEV1. Our results demonstrated inhaled furosemide significantly attenuated the bronchoconstrictive effect at 6 and 9 minutes after CAHC (p less than 0.05 and 0.029, respectively) when furosemide was compared to placebo and approached significance at 12 and 15 minutes after CAHC (p = 0.052 and 0.56, respectively). Inhaled furosemide attenuates CAHC but does not effect methacholine-induced bronchoconstriction.

Administration, Inhalation↗
PubMed1992

The effect of aerosol distribution on airway responsiveness to inhaled methacholine in patients with asthma.

It has been demonstrated that airway deposition of inhaled aerosols is more heterogeneous in patients with asthma than in normal subjects. Nevertheless, the influence of abnormal airway deposition on responses to bronchoactive aerosols is poorly understood. We altered bronchopulmonary deposition heterogeneity of methacholine aerosol in nine asymptomatic patients with asthma by controlling inspiratory flow at high (approximately 60 L/min) versus low (approximately 12 L/min) rates on 2 study days and determined the effect on the provocative dose of methacholine causing a 20% fall in FEV1 (PD20) (often used as a measure of airway responsiveness). Deposition uniformity was quantified from gamma-camera scans of the lungs in terms of the distribution of a technetium-labeled aerosol that was inhaled rapidly or slowly before the inhalation of methacholine. Increased deposition in an inner (large, central airways) versus an outer (peripheral airways and alveoli) zone of the right lung (inner/outer ratio, greater than 1) and higher values of skew (an index of deposition asymmetry) and kurtosis (an index of deposition range) indicated enhanced heterogeneity of deposition. Mean (+/- SD) inner/outer ratio was significantly higher during rapid inspiration compared to slow inspiration with 2.91 +/- 0.51 and 1.84 +/- 0.30, respectively (p less than 0.01). Mean skew and kurtosis were also significantly higher after rapid inspiration, with 1.12 +/- 0.35 and 3.86 +/- 1.25, respectively, compared to 0.74 +/- 0.36 and 2.64 +/- 0.77 after slow inhalation (p less than 0.01). Geometric mean PD20 methacholine was significantly reduced when the aerosol was inhaled rapidly, with 5.9 cumulative methacholine units compared to 15.7 units after slow inhalation (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1993

Relative potencies and time course of changes in adenosine 5'-monophosphate airway responsiveness with inhaled furosemide and bumetanide in asthma.

A randomized, double-blind, placebo-controlled study was conducted to compare the effects of two chemically unrelated "loop" diuretics, furosemide (40 mg) and bumetanide (2 mg) on the bronchoconstrictor response to inhaled adenosine 5'-monophosphate (AMP) in 12 subjects with asthma. In eight additional volunteers with asthma, we also carried out a separate randomized, double-blind study to examine in more detail the time course of change in bronchial reactivity to inhaled AMP after administration of nebulized furosemide and bumetanide. Inhaled loop diuretics significantly increased the provocative concentration of AMP causing a 20% fall in forced expiratory volume in 1 second (FEV1) from the value of 21.2 mg/ml (range, 2.5 to 96.9 mg/ml) after placebo administration to 83.4 mg/ml (range, 11.3 to 345.0 mg/ml) (p < 0.01) and 33.8 mg/ml (range, 4.7 to 120.9 mg/ml) (p < 0.05) after administration of furosemide and bumetanide, respectively. After placebo administration, the provocative concentration of AMP causing a 20% fall in FEV1 (PC20 AMP) at 10, 30, and 120 minutes did not differ significantly; their geometric mean (range) values were 57.8 mg/ml (10.9 to 341.0 mg/ml), 55.0 mg/ml (13.2 to 304.1 mg/ml), and 52.8 mg/ml (14.4 to 252.2 mg/ml), respectively. When compared with placebo, inhaled furosemide significantly reduced the airway responsiveness to AMP at all time points; the PC20 AMP values at 10, 30, and 120 minutes were 154.6 mg/ml (29.4 to 658.7 mg/ml) (p < 0.01), 142.6 mg/ml (25.5 to 639.9 mg/ml) (p < 0.01), and 103.9 mg/ml (12.5 to 605.5 mg/ml) (p < 0.05), respectively. The PC20 values for AMP after pretreatment with bumetanide were significantly increased up to 110.2 mg/ml (25.9 to 639.0 mg/ml) (p < 0.01) and to 92.0 mg/ml (21.6 to 531.7 mg/ml) (p < 0.05) at 10 and 30 minutes, respectively. At 120 minutes, inhaled bumetanide failed to affect AMP airway responsiveness; the PC20 AMP was not significantly different from that of placebo, with a value of 71.5 mg/ml (22.6 to 318.0 mg/ml). We conclude that comparable equidiuretic doses of furosemide and bumetanide are effective in attenuating the airway response to AMP, with furosemide being approximately 2.5 times more potent than bumetanide (p < 0.01). The time course of change in bronchial reactivity to AMP is similar for both drugs with a peak effect at 10 minutes. It is possible that the mechanism(s) underlying the protective effects of inhaled loop diuretics in asthma may be distinct from those responsible for their diuretic properties.

Adenosine Monophosphate↗
PubMed1994

Effects of long-term use of high-dose inhaled steroids on bone density and calcium metabolism.

BACKGROUND: Inhaled steroids are the mainstay in the antiinflammatory treatment of asthma. In the last few years, these agents have been used in increasing doses. Because high doses of inhaled steroids can reduce serum osteocalcin levels, there are concerns regarding their long-term effects on bone metabolism. METHODS: We examined the effects of doses of 800 micrograms/day or greater of beclomethasone or budesonide for more than 18 months in 37 asthmatic subjects (group A), matched to a control group of 37 asthmatic subjects using little or no inhaled steroids (< 500 micrograms, group B). All had a clinical evaluation, measurements of expiratory flows, and determination of serum creatinine, calcium, phosphate, gamma-glutamyl transpeptidase, alkaline phosphatase, cortisol, and osteocalcin levels. A 2-hour urinary sample was obtained for creatinine, calcium, phosphate, hydroxyproline, and cortisol measurements. Bone density was assessed at the lumbar spine level and at the hip with a Hologic-QDR-2000 osteodensitometer (Hologic, Boston, Mass.). RESULTS: The mean (+/- SD) daily dose of inhaled steroids over the last 2 years was 1140 +/- 353 micrograms in group A (mean duration of use of > 800 micrograms/day, 34.2 +/- 13.0 months) and 89 +/- 98 micrograms for group B (mean duration of use of < 500 micrograms/day, 15.7 +/- 18.8 months). The number of oral steroid treatments (< 15 days) during the last 2 years was small in the two groups, 0.92 +/- 1.27 in group A and 0.05 +/- 0.23 in group B (p > 0.05). The only differences between our two groups in terms of serum or urinary parameters were for mean osteocalcin level, which was lower in group A (2.16 +/- 1.09 ng/ml) than in group B (2.70 +/- 0.98 ng/ml) (p = 0.029), and in mean urinary phosphorous level, which was higher in group A (1.44 +/- 0.76 mmol/2 hr) than in group B (1.26 +/- 0.89 mmol/2 hr (p = 0.034). Mean urinary hydroxyproline levels were 15.51 +/- 6.98 mumol/2 hr in group A and 13.53 +/- 7.13 mumol/2 hr in group B (p > 0.05). Mean mineral bone densities of the lumbar spine and hip were similar in the two groups with values of 0.923 +/- 0.136 gm/cm2 and 0.719 +/- 0.147 gm/cm2 in group A and 0.933 +/- 0.154 gm/cm2 and 0.694 +/- 0.095 gm/cm2 in group B (p > 0.05). The T and Z scores for lumbar spine were -1.32 +/- 1.22 and -0.85 +/- 1.02 in group A and -1.19 +/- 1.33 and -0.72 +/- 1.08 in group B (p > 0.05). There was no correlation between the duration or dose of steroid use and bone density or osteocalcin. Although the serum osteocalcin level was lower in the group of subjects using high-dose inhaled steroids, suggesting an osteoblastic depression, bone density was not significantly different compared with the control group. CONCLUSIONS: This study shows that although the serum osteocalcin level was lower and the urinary phosphorus level was higher in subjects using high-dose inhaled steroids for a mean of 34 months, compared with a control group, no significant difference in bone density or other markers of bone metabolism was found between the two groups.

Administration, Inhalation↗
PubMed1991

Disposition and metabolism of [14C]1,2-dichloropropane following oral and inhalation exposure in Fischer 344 rats.

The objective of this study was to compare the disposition and metabolism of [14C]1,2-dichloropropane [( 14C]DCP) following oral and inhalation exposure since these two routes are of interest with regards to occupational and accidental exposure. [14C]DCP was administered orally to groups of four rats of each sex as a single dose of 1 or 100 mg/kg and as a multiple 1 mg/kg nonradiolabeled dose for 7 days followed by a single 1 mg [14C]DCP/kg dose on day 8. In addition, four rats of each sex were exposed to [14C]DCP vapors for a 6-h period in a head-only inhalation chamber at target concentrations of 5, 50 and 100 ppm. [14C]DCP was readily absorbed, metabolized and excreted after oral or inhalation exposure. For all treatment groups the principal routes of elimination were via the urine (37-65%) and expired air (18-40%). The tissues, carcass, feces and cage wash contained less than 11, 9.7 and 3.8% of the dose, respectively. The major urinary metabolites, as a group, from the oral and inhalation exposures were identified as three N-acetylcysteine conjugates of DCP, N-acetyl-S-(2-hydroxypropyl)-L-cysteine, N-acetyl-S-(2-oxopropyl)-L-cysteine and N-acetyl-S-(1-carboxyethyl)-L-cysteine. The majority (61-87%) of the expired volatile organic material was found to be parent DCP in all samples analyzed. Increasing the dose/concentration of [14C]DCP resulted in an increase in the amount of exhaled [14C]-volatile organics. The peak DCP blood concentrations (inhalation exposure) were not proportional to dose, indicating a dose-dependency in the blood clearance of DCP. Nonetheless, upon termination of exposure, DCP was rapidly eliminated from the blood. In all treatment groups, following oral and inhalation exposure the majority of the radioactivity was eliminated by 24 h postdosing and no differences were noted between sexes. Therefore, it can be concluded that in the rat the pharmacokinetics and metabolism of [14C]DCP are similar regardless of route of exposure or sex.

Administration, Inhalation↗