Glucokinase is a key regulator of glucose homeostasis, and small molecule allosteric activators of this enzyme represent a promising opportunity for the treatment of type 2 diabetes. Systemically acting glucokinase activators (liver and pancreas) have been reported to be efficacious but in many cases present hypoglycaemia risk due to activation of the enzyme at low glucose levels in the pancreas, leading to inappropriately excessive insulin secretion. It was therefore postulated that a liver selective activator may offer effective glycemic control with reduced hypoglycemia risk. Herein, we report structure-activity studies on a carboxylic acid containing series of glucokinase activators with preferential activity in hepatocytes versus pancreatic β-cells. These activators were designed to have low passive permeability thereby minimizing distribution into extrahepatic tissues; concurrently, they were also optimized as substrates for active liver uptake via members of the organic anion transporting polypeptide (OATP) family. These studies lead to the identification of 19 as a potent glucokinase activator with a greater than 50-fold liver-to-pancreas ratio of tissue distribution in rodent and non-rodent species. In preclinical diabetic animals, 19 was found to robustly lower fasting and postprandial glucose with no hypoglycemia, leading to its selection as a clinical development candidate for treating type 2 diabetes.

Compound 4 (PF-04971729) belongs to a new class of potent and selective sodium-dependent glucose cotransporter 2 inhibitors incorporating a unique dioxa-bicyclo[3.2.1]octane (bridged ketal) ring system. In this paper we present the design, synthesis, preclinical evaluation, and human dose predictions related to 4. This compound demonstrated robust urinary glucose excretion in rats and an excellent preclinical safety profile. It is currently in phase 2 clinical trials and is being evaluated for the treatment of type 2 diabetes.

The medicinal chemistry and preclinical biology of imidazopyridine-based inhibitors of diacylglycerol acyltransferase 2 (DGAT2) is described. A screening hit 1 with low lipophilic efficiency (LipE) was optimized through two key structural modifications: (1) identification of the pyrrolidine amide group for a significant LipE improvement, and (2) insertion of a sp(3)-hybridized carbon center in the core of the molecule for simultaneous improvement of N-glucuronidation metabolic liability and off-target pharmacology. The preclinical candidate 9 (PF-06424439) demonstrated excellent ADMET properties and decreased circulating and hepatic lipids when orally administered to dyslipidemic rodent models.

Glucokinase is a key regulator of glucose homeostasis and small molecule activators of this enzyme represent a promising opportunity for the treatment of Type 2 diabetes. Several glucokinase activators have advanced to clinical studies and demonstrated promising efficacy; however, many of these early candidates also revealed hypoglycemia as a key risk. In an effort to mitigate this hypoglycemia risk while maintaining the promising efficacy of this mechanism, we have investigated a series of substituted 2-methylbenzofurans as ''partial activators'' of the glucokinase enzyme leading to the identification of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2carboxamide as an early development candidate.

Brain mitochondrial cytochrome oxidase and respiratory activities were compared after in vivo and in vitro exposure to cyanide. For the in vivo studies, mice were exposed to a non-lethal (4 mg kg-1) or lethal (20 mg kg-1) dose of KCN. From these mice, purified brain mitochondria were prepared and cytochrome oxidase and respiratory activities measured. Results of these experiments revealed greater inhibition of cytochrome oxidase activity following a lethal (20 mg kg-1) than a non-lethal (4 mg kg-1) KCN dose (57 and 45% inhibition, respectively). Respiration states 3 and 4 of brain mitochondria prepared from mice that received 4 mg kg-1 KCN were inhibited by 15 and 20%, respectively. In mice that received a lethal 20 mg kg-1 KCN dose, respiration states 3 and 4 were each inhibited by ca. 30% (P < 0.05). In vitro, mitochondrial cytochrome oxidase activity was inhibited in a concentration-dependent fashion at cyanide concentrations of 10(-6)-10(-2) M. A biphasic inhibition of ADP-stimulated (state 3) respiration was observed. Cyanide concentrations of 10(-6)-10(-4) M produced only a 25% inhibition of respiration state 3, whereas 10(-3) M produced 80% inhibition. Because this dramatic inhibition only occurred at cyanide concentrations that caused > 50% inhibition of mitochondrial cytochrome oxidase activity, these findings suggest that a large proportion of cytochrome oxidase activity may be functional reserve and that cyanide poisoning likely involves other mechanisms in addition to inhibition of cytochrome oxidase.

Weak peroxisome proliferator-activated receptor (PPAR) a agonists (fibrates) are used to treat dyslipidemia. This study compared the effects of the potent and selective PPARa agonist CP-778875 on peroxisomal b-oxidation and cardiac and/or skeletal muscle injury with those of the weak PPARa agonist fenofibrate. We hypothesized that these muscle effects are mediated through the PPARa receptor, leading to increased b-oxidation and consequent oxidative stress. CP-778875 (5 or 500 mg/kg) and fenofibrate (600 or 2,000!1,200 mg/kg, dose lowered because of intolerance) were administered to rats for six weeks. Standard end points, serum troponin I, heart and skeletal muscle b-oxidation of palmitoyl-CoA, and acyl co-oxidase (AOX) mRNA were assessed. Both compounds dose-dependently increased the incidence and/or severity of cardiomyocyte degeneration and necrosis, heart weight, troponin I, and skeletal muscle degeneration. Mean heart b-oxidation (3.4-to 5.1-fold control) and AOX mRNA (2.4-to 3.2-fold control) were increased with CP-778875 500 mg/kg and both doses of fenofibrate. b-Oxidation of skeletal muscle was not affected by either compound; however, a significant increase in AOX mRNA (1.6-to 2.1-fold control) was observed with CP-778875 500 mg/kg and both doses of fenofibrate. Taken together, these findings were consistent with PPARa agonism and support the link between increased cardiac and skeletal muscle b-oxidation and resultant muscle injury in the rat.

The present article summarizes Metabolites in Safety Testing (MIST) studies on a glucokinase activator, N,N-dimethyl-5-((2-methyl-6-((5-methylpyrazin-2-yl)carbamoyl)benzofuran-4-yl)oxy)pyrimidine-2-carboxamide (PF-04937319), which is under development for the treatment of type 2 diametes mellitus. Metabolic profiling in rat, dog, and human hepatocytes revealed that PF-04937319 is metabolized via oxidative (major) and hydrolytic pathways (minor). N-Demethylation to metabolite M1 [N-methyl-5-((2-methyl-6-((5-methylpyrazin-2-yl)carbamoyl)benzofuran-4-yl)oxy)pyrimidine-2-carboxamide] was the major metabolic fate of PF-04937319 in human (but not rat or dog) hepatocytes, and was catalyzed by CYP3A and CYP2C isoforms. Qualitative examination of circulating metabolites in humans at the 100-and 300-mg doses from a 14-day multiple dose study revealed unchanged parent drug and M1 as principal components. Because M1 accounted for 65% of the drug-related material at steady state, an authentic standard was synthesized and used for comparison of steady-state exposures in humans and the 3-month safety studies in rats and dogs at the no-observed-adverse-effect level. Although circulating levels of M1 were very low in beagle dogs and female rats, adequate coverage was obtained in terms of total maximal plasma concentration (∼7.73 and 1.83) and area under the plasma concentration-time curve (AUC; 3.63 and 0.83 AUC) relative to the 100-and 300-mg doses, respectively, in male rats. Examination of primary pharmacology revealed M1 was less potent as a glucokinase activator than the parent drug (compound PF-04937319: EC 50 = 0.17 mM; M1: EC 50 = 4.69 mM). Furthermore, M1 did not inhibit major human P450 enzymes (IC 50 > 30 mM), and was negative in the Salmonella Ames assay, with minimal offtarget pharmacology, based on CEREP broad ligand profiling. Insights gained from this analysis should lead to a more efficient and focused development plan for fulfilling MIST requirements with PF-04937319.

Growth hormone secretagogues (GHSs) represent attractive therapeutic alternatives to recombinant growth hormone (GH), given their ability to amplify pulsatile hormone secretion in a relatively physiologic manner. CP-424,391 (391) is a novel, orally active pyrazolinone-piperidine [corrected] GHS. In rat pituitary cell cultures, 391 stimulated GH release with an EC50 = 3 nM. The addition of 391 to rat pituitary cells activated intracellular calcium signaling but did not elevate intracellular cyclic adenosine monophosphate (cAMP). 391 also modulated the effects of GH-releasing hormone and somatostatin on pituitary cell GH-release and intracellular signaling. In nonpituitary cell lines, the ability of 391 to stimulate intracellular signaling was dependent on the expression of recombinant human GHS receptor. Acute administration of 391 to anesthetized rats or to conscious dogs induced pulsatile release of G H in a dose-dependent manner. Plasma insulin-like growth factor-I (IGF-I) was elevated progressively over a 5-d course of daily oral dosing in dogs. Chronic oral administration of 391 augmented body weight gain in rats and dogs. Thus, the peptidomimetic GHS 391 has potential utility for the treatment of clinical conditions that could benefit from systemic augmentation of GH and IGF-I levels.