The purpose of this study was to investigate the release of the anti-
myopia drugs
atropine sulfate and
pirenzepine dihydrochloride from commercially available
soft contact lenses. Standard ultraviolet (UV) absorbance-concentration curves were generated for
atropine and
pirenzepine. Ten commercially available
contact lenses, including four multifocal
lenses, were loaded by soaking in
atropine or
pirenzepine solutions at two different concentrations (10 mg/mL and 1 mg/mL). The release of the drugs into
phosphate-buffered saline was determined over the course of 24 hours at 34°C using UV absorbance. Materials with surface charge released the greatest amount of
atropine when loaded with either concentration when compared to the other lens types (p<0.05), releasing upward of 1.026±0.035 mg/lens and 0.979±0.024 mg/lens from
etafilcon A and ocufilcon A, respectively. There were no significant differences in the amount of
atropine or
pirenzepine released from the multifocal and non-multifocal
lenses made from the same lens materials. Narafilcon A material demonstrated prolonged release of up to 8 hours when loaded with
pirenzepine, although the overall dose delivered from the lens into the
solution was among the lowest of the materials investigated. The rest of the
lenses reached a plateau within 2 hours of release, suggesting that they were unable to sustain drug release into the
solution for long periods of time. Given that no single method of
myopia control has yet shown itself to be completely effective in preventing
myopia progression, a combination of optical and pharmaceutical devices comprising a drug delivering
contact lens presents a novel
solution that warrants further investigation.