Transcleral delivery of triamcinolone acetonide and ranibizumab to retinal tissues using macroesis.
OBJECTIVE
To determine the feasibility of macroesis for the delivery of ranibizumab and triamcinolone acetonide via a transcleral route.


METHODS
Macroesis is a non-invasive method of drug delivery that uses alternating current (AC) to deliver drugs to target tissues. Two preclinical models of drug delivery were used for feasibility studies of delivering ranibizumab and triamcinolone acetonide to ocular tissues. In the first model, full-thickness sections of rabbit ocular tissue (conjunctiva to retina) were placed on an interdigitated electrode platform, and the drug was placed on the surface of the tissue. A non-uniform electrical field was applied to the ocular tissue, and electrical conductivity, a measurement of drug delivery, was monitored during the course of the experiment. In a second model, termed a 'simulated vitreous model,' the same full-thickness sections of rabbit ocular tissue were mounted below the electrode device, and the test compounds were placed on the electrodes. The fluid below the tissue, which simulated the vitreous cavity, was analysed using UV spectroscopy at the end of the study for the presence of drug.


RESULTS
In the electrical conductivity studies, the electric characteristics of the tissue-drug system clearly showed movement of the drug through the tissue to the dielectric sensor based on changes in the electrical conductivity of the tissue sample with triamcinolone. No change in tissue conductivity was observed when no drug was placed. No heat generation occurred during the course of the study; nor was any gross tissue destruction noted. In the simulated vitreous model, studies using triamcinolone yielded concentrations ranging from 0.280 to 0.970 mg/ml, depending on the voltage, frequency and time applied. In as little as 6.7 min, clinically efficacious doses could be obtained in the preclinical system. Studies using ranibizumab yielded concentrations of 0.070-0.171 mg/ml, depending on the voltage, frequency, and time applied. In as little at 6.7 min, 92.8% throughput could be achieved.


CONCLUSIONS
Successful delivery of ranibizumab and triamcinolone acetonide can be achieved with macroesis in preclinical studies.
Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA. singhr@ccf.org
Rishi P
RP
Singh
Michael Ellen
ME
Mathews
Michael
M
Kaufman
Alan
A
Riga
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000493:pharmacokinetics; D061067:Antibodies, Monoclonal, Humanized; D016503:Drug Delivery Systems; D004553:Electric Conductivity; D005240:Feasibility Studies; D005938:Glucocorticoids / Q000008:administration & dosage / Q000493:pharmacokinetics; D007478:Iontophoresis / Q000379:methods*; D023421:Models, Animal; D011817:Rabbits; D000069579:Ranibizumab; D012160:Retina / Q000378:metabolism*; D012590:Sclera; D014222:Triamcinolone Acetonide / Q000008:administration & dosage* / Q000493:pharmacokinetics
D000893:Anti-Inflammatory Agents; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D005938:Glucocorticoids; D014222:Triamcinolone Acetonide; D000069579:Ranibizumab