Glucagon-like peptide-1(7-37) has a larger volume of distribution than glucagon-like peptide-1(7-36)amide in dogs and is degraded more quickly in vitro by dog plasma.

The pharmacokinetic properties of glucagon-like peptide-1(7-36)amide (GLP-1(7-37) were compared. Four beagle dogs received on 4 separate occasions s.c. bolus doses of 50 micrograms/kg, and 2 min i.v. infusions of 50 micrograms/kg of each peptide. The plasma immunoreactivity of GLP-1 (P-GLP-1-IR) was measured by a sandwich enzyme-linked immunosorbent assay (ELISA). After i.v. infusion, the plasma half-life in the first-phase was 2.1 +/- 0.1 and 2.4 +/- 0.3 min, in the final-phase 68 +/- 6 and 81 +/- 3 min, the total plasma clearance 25 +/- 3 and 22 +/- 4 ml/kg.min, the volume of distribution at steady state 0.16 +/- 0.02 and 0.84 +/- 0.24 l/kg, and the mean residence time 6.2 +/- 0.3 and 36 +/- 5 min for GLP-1(7-36)amide and GLP-1(7-37), respectively. After s.c. administration, the maximum plasma concentration was reached after 15 +/- 5 and 19 +/- 4 min and the absolute bioavailability was 48 +/- 7 and 49 +/- 13% for GLP-1(7-36)amide and GLP-1(7-37), respectively. P-GLP-1-IR, measured by a radioimmunoassay (RIA), was considerably higher than when measured by ELISA. This discrepancy was due to cross-reactivity with metabolites of the parent peptide. The plasma degradation was studied in vitro in dog plasma at 37 degrees C, and the half-lives were found to be 61 +/- 9 and 132 +/- 16 min for GLP-1(7-36)amide and GLP-1(7-37), respectively (n = 6). Bacitracin inhibited the degradation of both peptides.

Tolerability, safety and pharmacokinetics of single dose and multiple dosing of the selective D1 antagonist NNC 01-0687 in healthy subjects.

Selective dopamine D1-receptor antagonists have been shown to exhibit similar effects in animal models for antipsychotic action as the selective D2 antagonists. NNC 01-0687, a benzazepine with selective and high affinity to the D1-receptor, was well tolerated by healthy subjects allocated to double blind, placebo controlled studies. Complaints of moderate restlessness and drowsiness were reported after administration of 25 mg NNC 01-0687, indicating the dose to be the maximum tolerated single dose. The highest multiple dose level of a daily dose of 45 mg NNC 01-0687 administered t.i.d. for 14 days was assessed as safe and well-tolerated with few reports of adverse events. Some alanine aminotransferase (ALT) elevations appeared in both treatment groups (active and placebo) and no evident influence of NNC 01-0687 on the liver function could be derived. No statistically significant or clinically relevant effects were observed in haematological parameters, urinalyses, blood pressure, heart rate, ECG or plasma levels of prolactin, cortisol or growth hormone. The plasma drug concentration curves indicated a fast absorption with tmax at 0.5-1 h and an apparent elimination half-life of 3-4 h. Both AUC and Cmax appeared to be linearly correlated to the dose, indicating linear pharmacokinetics. With similar Cmax and AUC on day 1 and day 10 no accumulation was observed. When administered just after lunch, the Cmax was reduced by 50-60% and the tmax increased to 3 h, but without change of AUC.

Determination of (+)-5-(2,3-dihydrobenzofuran-7-yl)-3-methyl-8-nitro-2,3,4,5- tetrahydro-1H-3-benzazepin-7-ol (NNC 01-0687), a novel dopamine D-1 receptor antagonist, in plasma by solid-phase extraction and high-performance liquid chromatography.

A fast and reliable method has been established for the determination of the dopamine D-1 receptor antagonist (+)-5-(2,3-dihydrobenzofuran-7-yl)-3-methyl-8-nitro-2,3,4,5-tetrahydro-1 H-3- benzazepin-7-ol (NNC 01-0687) in plasma. A combination of reversed-phase extraction on C18 columns and straight-phase high-performance liquid chromatographic analysis with ultraviolet detection at 287 nm resulted in very clean chromatograms. The limit of quantitation was about 1 ng/ml of plasma. Validation of the method showed good selectivity, linearity, recovery, accuracy and precision. Several modifications of the method were possible with little or no influence on the assay.