A Rapid Extraction Method to Quantify Drug Uptake in Contact Lenses

Area of Science:

• Ophthalmic Drug Delivery
• Contact Lens Technology
• Analytical Chemistry

Background:

• Contact lenses (CLs) are increasingly explored for ocular drug delivery.
• Quantifying drug uptake into CLs is crucial for developing effective delivery systems.
• Existing methods for drug quantification in CLs can be complex.

Purpose of the Study:

• To develop a straightforward extraction procedure for quantifying topical ocular drug uptake into various contact lens materials.
• To evaluate drug uptake differences between silicone hydrogel (SH) and conventional hydrogel (CH) CLs.
• To establish a reliable method for assessing drug-lens interactions.

Main Methods:

• Four silicone hydrogel (SH) and four conventional hydrogel (CH) CL types were incubated with four model drugs: natamycin, moxifloxacin, timolol maleate, and ketotifen fumarate.
• A simple methanol extraction procedure was employed over three cycles to recover drugs from the CLs.
• Drug concentrations were quantified using UV-Vis spectrophotometry at specific wavelengths for each drug.

Main Results:

• The majority of the drugs were efficiently extracted after the first cycle (P < 0.001).
• Conventional hydrogel (CH) CLs demonstrated significantly higher uptake for moxifloxacin and timolol maleate compared to silicone hydrogel (SH) CLs (P < 0.05).
• No significant differences in drug uptake were observed between CH and SH CLs for natamycin and ketotifen fumarate (P > 0.05).

Conclusions:

• A simple and effective extraction method for quantifying drug uptake into contact lenses has been successfully developed.
• This method provides a valuable tool for researchers investigating CL-based ocular drug delivery.
• The procedure is adaptable, allowing modifications to extraction parameters for diverse drug-lens combinations.