Pharmacokinetics and safety of paclitaxel delivery into porcine airway walls by a new endobronchial drug delivery catheter.

BACKGROUND AND OBJECTIVE: Intratumoral administration of chemotherapeutic agents is a treatment modality that has proven efficacious in reducing the recurrence of tumours and increases specificity of treatment while minimizing systemic side effects. Direct intratumoral injection of malignant airway obstruction has potential therapeutic benefits but tissue drug concentrations and side-effect profiles are poorly understood. METHODS: Bronchial wall injection of generic paclitaxel (PTX) (102 injections of 0.05, 0.5, 1.5 or 2.5 mg/mL in 10 healthy pigs), saline (14 injections in 2 healthy pigs) or Abraxane (ABX) (24 injections of 0.5 mg/mL in 4 healthy pigs) was performed with a microneedle infusion catheter. Local histopathology, plasma and tissue PTX concentrations were evaluated at 7, 20 or 28 days post-injection. RESULTS: Injection of generic PTX directly into the bronchial wall at doses up to 1.5 mg/mL only caused minimal tissue injury. Dose-limiting tissue reaction was observed at 2.5 mg/mL. Plasma PTX was detectable for up to 5 days but not at 28 days, with area under the curve (AUC)(0-5d) 20- to 50-fold lower than the AUC(0-∞) of 6300 ng h/mL for the approved intravenous dose. At 7 and 28 days post-injection, bronchial PTX tissue concentrations were above a 10-nmol/L cancer therapeutic level. PTX was not found in peripheral tissues. Similar results were observed between ABX and generic PTX. CONCLUSION: Results of these studies confirm the administration of PTX directly into the bronchial wall is safe and feasible. PTX was detectable in plasma for <7 days but tissue concentrations remained therapeutic throughout the follow-up period.

Experimental Pilot Study of a Novel Endobronchial Drug Delivery Catheter.

BACKGROUND: An endobronchial infusion catheter introduced through a flexible bronchoscope channel has not been previously described. The aim of this study was to evaluate the technical feasibility of a new device. METHODS: Four porcine models underwent bronchoscopy with the infusion catheter. In the first experiment, methylene blue was injected into airway in volumes of 0.1, 0.3, or 1.0 mL into 2 animals. One animal was killed at 1 hour and the other at 24 hours after the procedure and gross dye diffusion was visually assessed. In the second experiment, a mixture of 80% sterile normal saline and 20% contrast media was injected into the airway in volumes of 0.3, 1.0, and 3.0 mL into 2 animals. One animal was killed at 7 days and the other at 20 days. Histologic evaluations were performed according to a bronchial damage scoring system. RESULTS: There was no perioperative morbidity. In the first experiment, infusion volumes of 0.1, 0.3, and 1.0 mL resulted in dye surrounding 67%±29%, 55%±17%, and 80%±20% of the infusion-site circumference, and longitudinal distribution of 4.0±1.7, 8.1±4.1, and 18.0±3.0 mm each, respectively. In the second experiment, infusion of 0.3 to 3.0 mL resulted in mild injury, inflammation, and hemorrhage/fibrin/thrombus at 7 and 20 days after surgery. CONCLUSIONS: Endobronchial infusion of dye and contrast media by the endobronchial drug delivery catheter showed that the media spread in a dose-dependent manner macroscopically and histologically. Further investigation will be required to assess the catheter as a new tool for localized drug delivery into the airway.