Emulsion formulations of testosterone for nasal administration

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Nanotechnology

Background:

• Parenteral administration of testosterone is common, but oral delivery is limited by metabolism.
• The nasal route offers advantages over parenteral administration, but drug solubility is a challenge.
• Emulsion formulations are explored to enhance drug solubilization and residence time for nasal delivery.

Purpose of the Study:

• To develop and evaluate testosterone submicron emulsion formulations for nasal delivery.
• To investigate the effect of emulsion charge (zeta potential) on nasal bioavailability.
• To assess the potential of charged emulsions for improving testosterone absorption via the nasal route.

Main Methods:

• Preparation of three testosterone submicron emulsion formulations with varying zeta potentials (+24.8, -23.0, and 0.06 mV).
• Nasal administration of testosterone emulsions (3.8 mg/rabbit) in rabbits.
• Assessment of bioavailability using solid-phase extraction and High-Performance Liquid Chromatography (HPLC) analysis, compared to intravenous administration.

Main Results:

• Bioavailability of 55%, 51%, and 37% for positively, negatively, and neutrally charged emulsions, respectively.
• Positively and negatively charged emulsions demonstrated superior bioavailability compared to the neutral emulsion.
• Charged particle interactions with the nasal mucus layer are hypothesized to enhance drug absorption.

Conclusions:

• Testosterone emulsion formulations show promise for nasal drug delivery.
• Charged emulsions enhance drug absorption by prolonging contact with the nasal membrane.
• Further research into charged emulsion formulations could optimize nasal delivery of poorly soluble drugs like testosterone.