This invention relates to new pyridazinone derivatives. More particularly, it is concerned with a novel series of pyrido-pyridazinone acetic acid compounds. These compounds are useful in the control of certain chronic complications arising from diabetes mellitus (e.g., diabetic cataracts, retinopathy, nephropathy and neuropathy).
Past attempts to obtain new and better oral antidiabetic agents have, for the most part, involved an endeavor to synthesize new compounds that lower blood sugar levels. More recently, several studies have been conducted concerning the effect of various organic compounds in preventing or arresting certain chronic complications of diabetes, such as diabetic cataracts, nephropathy, neuropathy and retinopathy, etc. For instance, K. Sestanj et al. in U.S. Pat. No. 3,821,383 disclose that certain aldose reductase inhibitors like 1,3-dioxo-1H-benz[d,e]isoquinoline-2(3H)-acetic acid and some closely-related derivatives thereof are useful for these purposes even though they are not known to be hypoglycemic. Additionally, D. R. Brittain et al. in U.S. Pat. No. 4,251,528 disclose various aromatic carbocyclic oxophthalazinyl acetic acid compounds, which are reported to possess useful aldose reductase inhibitory properties. These compounds all function by inhibiting the activity of the enzyme aldose reductase, which is primarily responsible for catalyzing the reduction of aldoses (like glucose and galactose) to the corresponding polyols (such as sorbitol and galactitol) in the human body. In this way, unwanted accumulations of galactitol in the lens of galactosemic subjects and of sorbitol in the lens, retina, peripheral nervous system and kidney of diabetic subjects are prevented or reduced. As a result, these compounds control certain chronic diabetic complications, including those of an ocular nature, since it is already known in the art that the presence of polyols in the lens of the eye leads to cataract formation and concomitant loss of lens clarity.