Modulation of Insulin Secretion in Non‐insulin‐dependent Diabetes Mellitus by Two Novel Oral Hypoglycaemic Agents, NN623 and A4166

Abstract

Two novel oral hypoglycaemic agents, NN623 and A4166, have been developed and are now in phase II clinical trial. Both agents have several common characteristics from sulphonylureas. NN623 is a stereoisomer of derivatives of benzoic acid and A4166 is also a stereoisomer of phenylalanine derivative. The predominant mechanism of the action is thought to be like sulphonylureas. Both NN623 and A4166 occupy, at least partly, a common receptor site with glibenclamide and close the ATP-dependent K+ channel. They are rapidly absorbed from the intestine and are eliminated mainly into the bile. NN623 is about 10 times more potent in hypoglycaemic action than glibenclamide and 100 times more than A4166 in terms of dosage. When 1.0 mg NN623 or 60 mg A4166 was given orally in the post-absorptive state to healthy volunteers, both agents evoked hypoglycaemia by 40 min. The duration of hypoglycaemia after NN623 was longer than after A4166 by about 1 hour. The effect of food on their bioavailability is similar. Food has marked influence on the absorption of both drugs and on their efficacy. When 1 mg of NN623 or 60 mg of A4166 was administered just before the meal, Tmax of NN623 and A4166 was 34 +/- 18 min and 18 +/- 6 min, while T1/2 was 0.64 +/- 0.12 h and 0.98 +/- 0.06 h, respectively. The postprandial rise in plasma glucose was reduced at 45 min and thereafter over 4-h after 1.0 mg NN623 and at 30 min to 90 min after 60 mg A4166. Plasma insulin levels rose more than those after placebo from 30 to 90 min after NN623 and at 20 to 40 min after A4166. Both agents stimulated insulin release much more in the postprandial than in the fasting state. There was no difference in the bioavailability after 5 or 7 days of administration. However, when administered immediately after the meal, the absorption of both drugs was delayed and the rise in plasma absorption was not suppressed until 60 min after the meal. Both fasting and postprandial hyperglycaemia were reduced after 1 to 4 weeks of premeal treatment with 0.5 mg NN623 or 60 mg A4166 in subjects with NIDDM. Plasma glucose levels were decreased over 4 h after NN623 and over 1 h after A4166. The meal-induced insulin response was almost doubled by NN623 over 2 h and 1 h by A4166. There was no difference in the bioavailability after breakfast between the first and last administrations of both drugs. In conclusion, a rapid rise in plasma insulin levels is associated with the suppression of postprandial hyperglycaemia.