Precorneal residence time in humans of sodium hyaluronate as measured by gamma scintigraphy

Abstract

The aim of the present study was to quantify in man the distribution and clearance of two aqueous sodium hyaluronate (SH) solutions of 0.125% and 0.250% after the administration of 25 microliters onto the cornea. Isotonic phosphate buffer (PB) was used as a reference instillation. No systemic or local medication was given to the seven 18- to 30-year-old, healthy male volunteers. A detailed evaluation of the anterior segment of the eye, as well as a Schirmer test and a break-up time measurement, yielded results within the normal range. The clearance of 0.125% and 0.250% SH solutions radiolabelled with sodium pertechnetate Tc-99m was measured by gamma scintigraphy and compared with that of a PB solution tagged with the same radiolabel. There was no statistically significant difference between the quantities of 0.125% SH and PB solutions remaining in the precorneal space at 20 min (paired t-test, P = 0.78, n = 7). However, in comparing the 0.250% SH with the PB solution, we observed a statistically significant difference (P = 0.01, n = 7) in the amount remaining in the precorneal space after the same interval. Actually, 53% of the radiolabelled 0.250% SH solution remained on the cornea as compared with 30% for the 0.125% SH solution and 18.3% for the PB solution. These results suggest that an SH solution of 0.250% might have a prolonged residence time on the precorneal surface, and that SH could therefore be used as an additive in various drug-release systems for the eye.

Mucoadhesive drug delivery system: An overview

“…Poor retention of the gels at the site of application has been overcome by using mucoadhesive formulations. Certain mucoadhesive polymers, for example, sodium carboxymethylcellulose,[35] carbopol,[36] hyaluronic acid,[37] and xanthan gum,[38] undergo a phase change from liquid to semisolid. This change enhances the viscosity, which results in sustained and controlled release of drugs.…”

Efficacy and safety of 0.18% sodium hyaluronate in patients with moderate dry eye syndrome and superficial keratitis

“…Several authors obtained excellent results in treating this pathology with solutions containing sodium hyaluronate (SH) [5,6,9,12,17,27,33]. In brief, when these solutions were given at regular intervals, clinical signs were alleviated and tear film stability was improved, with better results compared to a control solution (the vehicle or saline).…”

Effectiveness of hyaluronan on corneal epithelial barrier function in dry eye

“…6 16 Among these products, hyaluronan, whose viscoelastic properties are known to help protect the corneal endothelium24 during intraocular surgical intervention, has also been shown to be of benefit as a tear substitute 714 15 The water retentive properties of hyaluronan, as reflected by diminished fluorescein turnover within the tear meniscus,11 radioactive molecule turnover in precorneal tears,12 helps to preserve tear fluid and also provides tear film stability in dry eyes 10. Moreover, hyaluronan is known to actively promote corneal wound healing by accelerating cell migration 8.…”