Jet nebulization of prostaglandin E1 during neonatal mechanical ventilation: stability, emitted dose and aerosol particle size

Stability of prostaglandin E1 solutions stored in polypropylene syringes for continuous intravenous administration to newborns

Objective

We aimed to monitor the physicochemical stability of prostaglandin E₁ (PGE₁) 1.5 and 15 µg/mL in 10% dextrose stored in polypropylene syringes.

Methods

We developed a liquid chromatography-high resolution mass spectrometry (LC-HRMS) method to detect and quantify levels of PGE₁. Method selectivity was performed with a mixture of PGE₁ and its degradation products. Forced degradation tests were performed to determine which degradation products were most likely to form. PGE₁ injection solutions in 10% dextrose were stored in unprotected and shielded-from-light polypropylene syringes in a climatic chamber. Samples were taken immediately after preparation (T₀) and after 24, 48, 72 and 168 hours for analysis. PGE₁ solutions were considered stable if ≥90.0% of the initial concentration was retained.

Results

The LC-HRMS method was validated in the range of 0.086-0.200µg/mL PGE₁ with trueness values between 98.2% and 100.3%, and repeatability and intermediate precision values of <2.2%and <4.7%, respectively. The quantification and detection limits of the method were 0.086 and 0.026µg/mL, respectively. PGE₁ and its degradation products were resolved chromatographically. PGE₁ injection solutions were≥90.0%stable after 48hours in unprotected from light (UPL) syringes. The solutions remained clear without precipitation, colour or pH modification and subvisible particles within the permitted levels. Prostaglandin A₁ was the sole degradation product observed.

Conclusions

A LC-HRMS method to evaluate PGE₁ stability in a 10% dextrose was developed and validated. PGE₁ 1.5 and 15µg/mL in 10% dextrose solution are stable for 48hours when stored at 30ºC in UPL polypropylene syringes.

Iloprost drug delivery during infant conventional and high-frequency oscillatory ventilation

Iloprost is a selective pulmonary vasodilator approved for inhalation by the Food and Drug Administration. Iloprost has been increasingly used in the management of critically ill neonates with hypoxic lung disease. This in vitro study was designed to test the hypothesis that aerosol drug delivery could be effectively administered to infants with both conventional ventilation and high-frequency oscillatory ventilation (HFOV). A neonatal test lung model configured with newborn lung mechanics was ventilated with a conventional ventilator and an HFOV with standard settings. A vibrating-mesh nebulizer was placed (1) proximal to the patient airway in the inspiratory limb between the humidifier probe and patient wye (conventional) as well as between the vent circuit and the endotracheal tube (ETT) for HFOV and (2) between the ventilator and humidifier (distal). Iloprost was nebulized in three separate runs using three new nebulizers in each of the circuit locations. A collecting filter was placed at the distal end of the ETT for each trial. Iloprost was quantified using high-performance liquid chromatography. The percentage of nominal dose delivered was greater with the nebulizer placed proximal to the airway for conventional ventilation (10.74% ± 2%) and HFOV (29% ± 2%) than with it placed in the distal position (2.96% ± 0.2% vs. 0.96% ± 0.8%, respectively; P < 0.05). Drug delivery in proximal position was nearly threefold greater during HFOV than during conventional ventilation. In conclusion, iloprost drug delivery was best achieved when the nebulizer was placed proximal to the patient airway during neonatal mechanical ventilation. Drug delivery appears to be more efficient during HFOV than during conventional ventilation.

The function and performance of aqueous aerosol devices for inhalation therapy

OBJECTIVES

In this review paper, we explore the interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations for several types of devices, namely jet, ultrasonic and vibrating-mesh nebulizers; colliding and extruded jets; electrohydrodynamic mechanism; surface acoustic wave microfluidic atomization; and capillary aerosol generation.

KEY FINDINGS

Nebulization is the transformation of bulk liquids into droplets. For inhalation therapy, nebulizers are widely used to aerosolize aqueous systems, such as solutions and suspensions. The interaction between the functioning mechanism of different nebulizers and the physicochemical properties of the formulations plays a significant role in the performance of aerosol generation appropriate for pulmonary delivery. Certain types of nebulizers have consistently presented temperature increase during the nebulization event. Therefore, careful consideration should be given when evaluating thermo-labile drugs, such as protein therapeutics. We also present the general approaches for characterization of nebulizer formulations.

SUMMARY

In conclusion, the interplay between the dosage form (i.e. aqueous systems) and the specific type of device for aerosol generation determines the effectiveness of drug delivery in nebulization therapies, thus requiring extensive understanding and characterization.

Ciprofloxacin plus erythromycin or ambroxol ameliorates endotracheal tube-associated Pseudomonas aeruginosa biofilms in a rat model

BACKGROUND AND OBJECTIVE

Pseudomonas aeruginosa is a multi-drug resistant bacterium, with its biofilm-growing mucoid (alginate-producing) strains being particularly resistant. As atomized drug administration is a common practice in pediatric patients, we compared the effect of inhalational therapy with erythromycin plus ciprofloxacin, with that of ambroxol plus ciprofloxacin, against biofilm producing strains of P. aeruginosa.

RESULTS

Both combined treatment regimens were associated with a significant reduction in bacterial counts in endotracheal (ET) tubes and lungs, as compared to that observed with ambroxol and erythromycin monotherapies (P<0.05). Ciprofloxacin plus ambroxol appeared to have a higher efficacy than ciprofloxacin plus erythromycin, both in lowering bacterial counts (P<0.05) and in disrupting the structural integrity of biofilm. Histopathological changes in the lungs were milder in the two combined treatment groups, as compared to that in groups treated with single drugs.

CONCLUSION

Erythromycin or ambroxol in combination with ciprofloxacin could eliminate P. aeruginosa biofilms. When combined with ciprofloxacin, ambroxol outperformed erythromycin in eradicating P. aeruginosa biofilm.

Inhaled PGE1 in neonates with hypoxemic respiratory failure: two pilot feasibility randomized clinical trials

Background

Inhaled nitric oxide (INO), a selective pulmonary vasodilator, has revolutionized the treatment of neonatal hypoxemic respiratory failure (NHRF). However, there is lack of sustained improvement in 30 to 46% of infants. Aerosolized prostaglandins I₂ (PGI₂) and E₁ (PGE₁) have been reported to be effective selective pulmonary vasodilators. The objective of this study was to evaluate the feasibility of a randomized controlled trial (RCT) of inhaled PGE₁ (IPGE₁) in NHRF.

Methods

Two pilot multicenter phase II RCTs are included in this report. In the first pilot, late preterm and term neonates with NHRF, who had an oxygenation index (OI) of ≥15 and <25 on two arterial blood gases and had not previously received INO, were randomly assigned to receive two doses of IPGE₁ (300 and 150 ng/kg/min) or placebo. The primary outcome was the enrollment of 50 infants in six to nine months at 10 sites. The first pilot was halted after four months for failure to enroll a single infant. The most common cause for non-enrollment was prior initiation of INO. In a re-designed second pilot, co-administration of IPGE₁ and INO was permitted. Infants with suboptimal response to INO received either aerosolized saline or IPGE₁ at a low (150 ng/kg/min) or high dose (300 ng/kg/min) for a maximum duration of 72 hours. The primary outcome was the recruitment of an adequate number of patients (n = 50) in a nine-month-period, with fewer than 20% protocol violations.

Results

No infants were enrolled in the first pilot. Seven patients were enrolled in the second pilot; three in the control, two in the low-dose IPGE₁, and two in the high-dose IPGE₁ groups. The study was halted for recruitment futility after approximately six months as enrollment targets were not met. No serious adverse events, one minor protocol deviation and one pharmacy protocol violation were reported.

Conclusions

These two pilot RCTs failed to recruit adequate eligible newborns with NHRF. Complex management RCTs of novel therapies for persistent pulmonary hypertension of the newborn (PPHN) may require novel study designs and a longer period of time from study approval to commencement of enrollment.

Trial registration: ClinicalTrials.gov

Pilot one: NCT number: 00598429 registered on 10 January 2008. Last updated: 3 February 2011.

Pilot two: NCT number: 01467076 17 October 2011. Last updated: 13 February 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-486) contains supplementary material, which is available to authorized users.

Effect of aerosolized PGE(1) on the ductus arteriosus of neonatal swine

BACKGROUND

Inhaled PGE(1) (IPGE(1)) is a potential pulmonary vasodilator in neonatal respiratory failure. However, its effect on the patency of the ductus arteriosus (DA) has not been described.

OBJECTIVE

To investigate the effect of IPGE(1) on the DA in healthy piglets.

DESIGN/METHODS

IPGE(1) (1200ng/kg/min) [Study] or nebulized saline [Control] was administered using a jet nebulizer. Transthoracic echocardiography (TTE) was performed prior to (T0) and after 24h of aerosol therapy (T24). The DA was also evaluated histomorphologically at autopsy.

RESULTS

Fifteen piglets, 1-9 days old (study=9; control=6), were evaluated for DA patency. Study piglets received IPGE(1) for 12-24h. TTE was performed on 12 piglets at T0. Nine animals showed no ductal flow and 3 (1 study, 2 control) had a small DA. TTE at T24 in 5 animals showed no change in DA. At autopsy, the ductal diameter and histologic maturity stage were comparable in study and control animals.

CONCLUSIONS

High dose IPGE(1) given for 12-24h does not exert significant effect on the DA of healthy term piglets as evaluated by echocardiography and histomorphology. We conclude that ductal patency in neonates is influenced not only by prostaglandins but also by factors like hypoxemia, prematurity, and heart disease.

Aerosol delivery in ventilated newborn pigs: an MRI evaluation

Pulmonary deposition of inhaled drugs in ventilated neonates has not been studied in vivo. The objective of this study was to evaluate pulmonary delivery of gadopentetate dimeglumine (Gd-DTPA) following nebulization in ventilated piglets using magnetic resonance imaging. Seven ventilated piglets (5 +/- 2 d old, weight 1.8 +/- 0.5 kg) were scanned in the Bruker/Siemens 4T magnetic resonance scanner using T1 weighted spin-echo sequence. Aerosols of Gd-DTPA were generated continuously using the MiniHeart jet nebulizer. Breath-hold coronal images were obtained before and every 10 min during aerosolized Gd-DTPA for 90 min. Signal intensity (SI) changes over the lungs, kidneys, liver, skeletal muscle, and heart were evaluated. A significant increase in SI was observed in the lungs, kidney, and liver at 10, 20, and 40 min respectively after start of aerosol. At the end of 90 min, the SI increased by 95%, 101%, and 426% over the right lung, left lung, and kidney, respectively. A much smaller increase in SI was observed over the liver. In conclusion, we have demonstrated effective pulmonary aerosol delivery within 10 min of contrast nebulization in ventilated piglets. Contrast visualization in the kidneys within 20 min of aerosol initiation reflects alveolar absorption, glomerular filtration and renal concentration.

Toxicity of prolonged high dose inhaled PGE1 in ventilated neonatal pigs

OBJECTIVE

To study the toxicity of inhaled PGE1 (IPGE1) in healthy ventilated piglets.

METHODS

Mechanically ventilated anesthetized piglets received either high dose IPGE1 (IPGE1 group) or nebulized saline (control group) continuously for 24h. Cardio-respiratory parameters, complete blood counts and serum electrolytes were monitored. Lung histology was evaluated by a masked pathologist for the severity (minimal, moderate, and severe) and extent (focal, multifocal, and diffuse) of histologic injury.

RESULTS

Ten neonatal pigs were instrumented. Four received nebulized saline and six received high dose IPGE1. There was no evidence of adverse cardio-respiratory effects, bronchial irritation or hypernatremia related to IPGE1. Diffuse/multifocal alveolar edema and focal polymorphonuclear infiltration was observed in both the control and IPGE1 groups suggesting that alveolar alterations may be secondary to effects of mechanical ventilation. The most distinct histomorphological abnormalities observed in the IPGE1 animals were focal ulceration, flattening of the bronchial epithelium and loss of cilia of moderate to severe degree in the trachea and bronchi.

CONCLUSION

In healthy piglets, inhalation of high dose IPGE1 was not associated with adverse cardiorespiratory effects, bronchial irritation, or hypernatremia and produced minimal signs of pulmonary toxicity even after 24h. Prolonged inhalation of high dose PGE1 therefore appears safe in newborn piglets.