Nebulizer Choice Affects the Airway Targeting of Amphotericin B Lipid Complex Aerosols

Background: Although amphotericin B is highly effective against fungal infections, it has serious adverse effects. Encapsulation of amphotericin B in liposomes reduces its potential for systemic side effects. Administration of liposomal amphotericin via aerosols to the lungs (a main portal of fungal infections) further reduces its toxicity while increasing its therapeutic index and prophylactic efficacy. However, the effectiveness of aerosol therapy depends on the dose deposited and the distribution of the drug within the lungs. The size of the aerosol particle is an important factor that affects the distribution of the drug within the lungs and the effectiveness of therapy. Objective: This study aims to determine the physicochemical suitability of amphotericin B lipid complex (ABLC) for aerosolization and to compare the performance of 3 commercially available air jet nebulizers in generating ABLC aerosols in terms of aerosol output (mg/min) and drug amount aerosolized within various particle-size ranges, the latter of which affects airway deposition. Methods: We aerosolized 2 concentrations (5 mg/mL and 10 mg/mL) of ABLC and evaluated their physicochemical properties, including osmolality, pH, and viscosity. The aerosolization performances of Pulmo-Aide/Micromist, Envoy/Sidestream, and Proneb/Pari LC Star systems were then evaluated in terms of output rate (mg/min), percent aerosolized, and milligram per minute of drug aerosolized within particle-size ranges of 1 to 3.5 µm, 3.5 to 6 µm, and 1 to 6 µm. Results: The output rate increased with higher drug concentration regardless of device. Pulmo-Aide/Micromist and Envoy/Sidestream showed high output rates. Proneb/Pari LC Star and Envoy/Sidestream delivered the highest percentages of aerosolized particles within the 1 to 3.5 µm particle-size range, favoring deposition within the alveolar/distal end area of the airways. Pulmo-Aide/Micromist delivered a higher percentage of aerosol within the 3.5 to 6 µm than the 1 to 3.5 µm particle-size range, favoring deposition in the central airways. Conclusion: The present study shows that different nebulizers produced different size ranges of aerosolized particles of ABLC preferentially targeting different parts of the airways. Thus, effective aerosol therapies may require the evaluation of different nebulizers for optimal targeting.

Efficacy of inhaled ciprofloxacin in the management of non-cystic fibrosis bronchiectasis

Non-cystic fibrosis bronchiectasis (NCFBE), a historically under-recognized chronic respiratory condition, is a significant diagnosis currently experiencing a resurgence of interest in its clinical management. Ciprofloxacin is part of the current armamentarium used in the treatment of the recurrent respiratory tract infections seen in NCFBE. Inhaled ciprofloxacin, a novel method of drug delivery for the fluoroquinolone class, is being actively investigated. The inhaled formulation is designed to enhance drug delivery to the site of infection in the lung while minimizing the risk of systemic toxicity. This review summarizes the pharmacology and pharmacokinetics of ciprofloxacin and the rationale for the development of an inhaled formulation for NCFBE. Preclinical and clinical data regarding current development of inhaled ciprofloxacin formulations is also evaluated. Lastly, the anticipated role of inhaled ciprofloxacin in the management of NCFBE is discussed, including future considerations and potential limitations of therapy.

Use of nebulized antimicrobial agents in burned and mechanically ventilated patients with persistent Acinetobacter baumannii, Pseudomonas aeruginosa, or Enterobacteriacea

BACKGROUND

Nebulized antibiotics are used to locally treat colonizations of multi-resistant organisms. Prior systemic nephrotoxic antibiotic use with serum creatinine rises warranted an alternative therapy in 69 ventilator-dependent patients with persisting sputum cultures and need for ventilatory support.

MATERIALS AND METHODS

Following IRB approval, retrospective patient data were reviewed. Analysis included comparison of these 69 patients (71 treatments) to 142 Gram-negative infected burn patients matched for age and burn size.

RESULTS

Mean pooled age and burn wound percent for the 71 triplicates (n=211 patients) were 55.6±18.3 years and 27.4±22.3% burns. Fifty-seven of 69 (83%) patients had inhalation injuries and 54 of 69 (78%) patients survived. Nebulizations averaged 6.8±3.3 days (range 3-12 days). Serum creatinine rose in 2 patients receiving colistimethate nebulizations, known to cause nephrotoxicity following nebulization. Triplicate comparisons via ANOVA noted prolonged ventilatory support (F=13.39; p≪0.05) and length of stay (F=6.11; p≪0.5). Variance was attributed to the sicker nebulized patients. Twenty-four inhalation injury-only triplicates further confirmed that nebulized patient subgroup was more ill.

CONCLUSION

Short duration antibiotic nebulization may allow higher intra-tracheal antibiotic concentrations and may facilitate weaning from the ventilator by reducing bacterial bioburden.

Stability of colistimethate sodium in aqueous solution

Colistimethate sodium, increasingly used to treat multidrug-resistant Gram-negative infections, spontaneously hydrolyzes to form colistin A (polymyxin E1) and B (polymyxin E2/B) when mixed with water. High levels of these active breakdown products at the time of administration have been associated with nephrotoxicity and even death. In this study, reconstituted colistimethate sodium was shown to be stable (<1.0% colistin A/B formation) for up to 24 h when stored at 21, 0, -20, and -70°C.

Inhaled aztreonam lysine for cystic fibrosis pulmonary disease-related outcomes

OBJECTIVE

To evaluate the pharmacology, clinical efficacy, and safety of aztreonam lysine for inhalation (AZLI) for cystic fibrosis (CF)-related signs and symptoms of pulmonary disease.

DATA SOURCES

Literature was searched in MEDLINE through PubMed and cross-referenced with EMBASE (1980-June 2012). The key search terms used were aztreonam lysine, nebulized, inhaled, and cystic fibrosis. Bibliographies of selected articles were used to identify additional references. Ongoing trials were identified through a review of Web site trial registries.

STUDY SELECTION AND DATA EXTRACTION

Articles were limited to those written in English about studies conducted in humans. Studies included in this review examined both adult and pediatric patients with CF.

DATA SYNTHESIS

Aztreonam lysine is an inhaled monocyclic β-lactam antibiotic approved for use in the CF population. Four completed clinical trials with peer-reviewed published data were reviewed to assess the efficacy and safety of single-course AZLI; a fifth trial assessed the safety and efficacy of repeat courses of AZLI. None of these trials compared AZLI in a head-to-head manner with tobramycin for inhalation. In patients with moderate to severe pulmonary disease, AZLI administration improved forced expiratory volume in 1 second measurements, decreased sputum bacterial Pseudomonas aeruginosa density, and improved symptoms. Adverse effects in clinical trials were generally mild and similar to those with placebo.

CONCLUSIONS

AZLI is safe and effective for management of pulmonary-related symptoms in patients with CF who are colonized with P. aeruginosa and have moderate to severe pulmonary disease. Additional trial data comparing AZLI with tobramycin are warranted to further establish the place of AZLI in therapy.

Medical device-associated infections in the long-term care setting

Indwelling medical devices are increasingly used in long-term care facilities (LTCFs). These devices place residents at a heightened risk for infection and colonization and infection with multidrug-resistant organisms. Understanding the risk and pathogenesis of infection associated with commonly used medical devices can help facilitate appropriate therapy. Programs to minimize unnecessary use of indwelling medical devices in residents and maximize staff adherence to infection control and maintenance procedures are essential features of a LTCF infection prevention program. LTCFs that provide care for large numbers of residents with indwelling medical devices should routinely perform surveillance for device-related infections and develop systems for assessing the safety and efficacy of newly introduced device-related technology.

Inhaled antibiotic therapy for ventilator-associated tracheobronchitis and ventilator-associated pneumonia: an update

Ventilator-associated pneumonia (VAP) remains a leading cause of morbidity and mortality in mechanically-ventilated patients in the Intensive Care Unit (ICU). Ventilator-associated tracheobronchitis (VAT) was previously believed to be an intermediate stage between colonization of the lower respiratory tract and VAP. More recent data, however, suggest that VAT may be a separate entity that increases morbidity and mortality, independently of the occurrence of VAP. Some, but not all, patients with VAT progress to develop VAP. Although inhaled antibiotics alone could be effective for the treatment of VAP, the current consensus of opinion favors their role as adjuncts to systemic antimicrobial therapy for VAP. Inhaled antibiotics are increasingly employed for salvage therapy in patients with VAP due to multi-drug resistant Gram-negative bacteria. In contrast to VAP, VAT could be effectively treated with inhaled antibiotic therapy alone or in combination with systemic antimicrobials.

The potential for inhaled treprostinil in the treatment of pulmonary arterial hypertension

Inhaled treprostinil is a safe and well-tolerated approved pharmaceutical for the treatment of pulmonary arterial hypertension. In a series of open-label studies and in the pivotal trial with 253 patients, this long-acting prostacyclin analogue demonstrated pronounced pulmonary selectivity of vasodilatory effects, improved physical capacity and excellent tolerability and safety following aerosol administration. For efficient treatment, only four daily inhalations of treprostinil are necessary compared with six to nine in iloprost aerosol therapy. This review describes in detail the development of inhaled treprostinil, starting with intravenous epoprostenol followed by inhaled iloprost and subcutaneous treprostinil, all three representing well-established and widely approved prostanoid therapies for pulmonary hypertension.

In order to circumvent the drawbacks of intravenous epoprostenol, stable prostacyclin analogues with similar pharmacological properties have been investigated. In addition, alternative routes of administration have been proposed and evaluated, mainly inhaled and subcutaneous delivery. The concept of inhaled treprostinil was to combine the pulmonary selectivity of an aerosolized vasodilator with the long-acting effects of a stable prostacyclin analogue.

Pulmonary arterial hypertension remains, however, a severe, life-threatening disease, in spite of the enormous progress in specific drug therapy over the last decade. Therefore, further improvement of drug therapy will be essential, with clear potential for inhaled treprostinil: a reduction of inhalation frequency and duration would markedly improve quality of life and compliance, and a longer-lasting local prostanoid effect might further enhance the efficacy of inhaled treprostinil. The advantageous pharmacological properties of treprostinil offer the opportunity to establish a convenient metered dose inhaler as a delivery system, to combine inhaled treprostinil with available or future drugs for pulmonary arterial hypertension, or to develop sustained release formulations of treprostinil suitable for inhalation based on liposomes or biodegradable nanoparticles.