Pulmonary absorption of liposomal levonorgestrel

Area of Science:

• Pharmacokinetics and Drug Delivery

Background:

• Oral administration of Levonorgestrel (LN) can lead to side effects and fluctuating plasma concentrations.
• Pulmonary drug delivery offers a potential alternative for achieving sustained therapeutic effects.

Purpose of the Study:

• To evaluate the bioavailability and pharmacokinetic profile of Levonorgestrel (LN) after pulmonary administration.
• To compare pulmonary delivery with oral administration for prolonged effective drug concentration and reduced side effects.

Main Methods:

• Levonorgestrel (LN) formulations (plain suspension, physical mixture, liposomal encapsulation) were administered intratracheally to rats.
• A 10 µg drug suspension was administered orally as a control.
• Plasma drug concentrations were analyzed using spectrofluorimetry over time.

Main Results:

• Pulmonary administration yielded high relative bioavailability (97.6%–109.9%) for all LN formulations.
• Pulmonary delivery maintained effective plasma drug concentrations for up to 60 hours, significantly longer than oral administration (30 hours).
• Pulmonary routes showed lower Cmax but prolonged drug presence compared to oral routes.

Conclusions:

• Pulmonary delivery of Levonorgestrel (LN) formulations demonstrates superiority in maintaining effective therapeutic concentrations.
• This method is expected to reduce dosing frequency and systemic side effects associated with oral LN administration.
• Pulmonary drug delivery is a promising strategy for sustained Levonorgestrel (LN) therapy.