To determine efficacy and therapeutic index in the context of ocular hypotensive activity of the new ethacrynic acid (ECA) derivatives of the 8000 series (SA8248 and SA8389), 9000 series (SA9000, SA9622 and SA9995) and ticrynafen, we undertook a comparative evaluation of the dose-dependent effects of these compounds on human trabecular meshwork (HTM) cell shape, actin cytoskeletal organization, focal adhesions and transcellular fluid flow. Responses were either scored using an arbitrary scale of 1—5 or quantified. Compounds of the 9000 series (SA9995>SA9000>SA9622) were found to be 14- to 20-fold more potent than ECA, ticrynafen or analogs from the 8000 series (SA8389>SA8248) in terms of ability to induce cell shape alterations in HTM cells. Similarly, compounds of the 9000 series (SA9995>SA9622>SA9000) were found to be much stronger (2 to 20 fold) than ECA, ticrynafen or analogs of the 8000 series in terms of affecting decreases in actin stress fiber content in HTM cells. Analogs of the 9000 series (SA9622>SA9995>SA9000) were also observed to be 8 to 10 fold more potent than ECA (SA8389>ECA>SA8248>ticrynafen) at eliciting decreases in cellular focal adhesions. Interestingly, analogs of the 9000 series (SA9000>SA9622>SA9995) and SA8248 demonstrated a huge increase (by many folds) in transcellular fluid flow of HTM cell monolayers as compared to ECA and ticrynafen. Collectively, these analyses revealed that the structural modification of ECA improves its ocular hypotensive efficacy, indicating that the SA9000 series compounds might be promising novel ocular hypotensive drugs.
2005 The Pharmaceutical Society of Japan