Alan David Palkowitz

Angiotensin ii antagonists

Acute blockade of the renin-angiotensin system with the parenterally active angiotensin II antagonist saralasin has been shown to effectively lower blood pressure in a large fraction of patients with essential hypertension and to improve hemodynamics in some patients with congestive heart failure. It is now possible to antagonize chronically angiotensin II at its receptor using the non-peptide angiotensin II inhibitor losartan (DuP 753, MK 954). When administered by mouth, this compound induces a dose-dependent inhibition of the pressor response to exogenous angiotensin II. This effect is closely related to circulating levels of the active metabolite E3174. Preliminary studies performed in hypertensive patients suggest that losartan has a blood pressure lowering action equivalent to that of an ACE inhibitor. Whether this compound will compare favorably with ACE inhibitors requires however further investigation.

Open Innovation for Phenotypic Drug Discovery: The PD2 Assay Panel

Phenotypic lead generation strategies seek to identify compounds that modulate complex, physiologically relevant systems, an approach that is complementary to traditional, target-directed strategies. Unlike gene-specific assays, phenotypic assays interrogate multiple molecular targets and signaling pathways in a target “agnostic” fashion, which may reveal novel functions for well-studied proteins and discover new pathways of therapeutic value. Significantly, existing compound libraries may not have sufficient chemical diversity to fully leverage a phenotypic strategy. To address this issue, Eli Lilly and Company launched the Phenotypic Drug Discovery Initiative (PD2), a model of open innovation whereby external research groups can submit compounds for testing in a panel of Lilly phenotypic assays. This communication describes the statistical validation, operations, and initial screening results from the first PD2 assay panel. Analysis of PD2 submissions indicates that chemical diversity from open source collaborations complements internal sources. Screening results for the first 4691 compounds submitted to PD2 have confirmed hit rates from 1.6% to 10%, with the majority of active compounds exhibiting acceptable potency and selectivity. Phenotypic lead generation strategies, in conjunction with novel chemical diversity obtained via open-source initiatives such as PD2, may provide a means to identify compounds that modulate biology by novel mechanisms and expand the innovation potential of drug discovery.

Long‐Term Dosing of Arzoxifene Lowers Cholesterol, Reduces Bone Turnover, and Preserves Bone Quality in Ovariectomized Rats

Long‐term effects of a new selective estrogen receptor modulator (SERM) arzoxifene were examined in ovariectomized (OVX) rats. Arzoxifene was administered postoperatively (po) at 0.1 mg/kg per day or 0.5 mg/kg per day to 4‐month‐old rats, starting 1 week after OVX for 12 months. At study termination, body weights for arzoxifene groups were 16–17% lower than OVX control, which was caused by mainly reduced gain of fat mass. Longitudinal analysis of the proximal tibial metaphysis (PTM) by computed tomography (CT) at 0, 2, 4, 6, 9, and 12 months showed that OVX induced a 22% reduction in bone mineral density (BMD) at 2 months, which narrowed to a 12% difference between sham‐operated (sham) and OVX rats by 12 months. Both doses of arzoxifene prevented the OVX‐induced decline in BMD. Histomorphometry of the PTM showed that arzoxifene prevented bone loss by reducing osteoclast number in OVX rats. Arzoxifene maintained bone formation indices at sham levels and preserved trabecular number above OVX controls. Micro‐CT analysis of lumbar vertebrae showed similar preservation of BMD compared with OVX, which were not different from sham. Compression testing of the vertebra and three‐point bending testing of femoral shaft showed that strength and toughness were higher for arzoxifene‐treated animals compared with OVX animals. Arzoxifene reduced serum cholesterol by 44–59% compared with OVX. Uteri wet weight from arzoxifene animals was 38–40% of sham compared with OVX rats, which were 29% of sham. Histology of the uterine endometrium showed that cell heights from both doses of arzoxifene were not significantly different from OVX controls. In summary, treatment of OVX rats with arzoxifene for nearly one‐half of a lifetime maintained beneficial effects on cholesterol and the skeleton. These data suggest that arzoxifene may be a useful therapeutic agent for osteoporosis in postmenopausal women.

Reversal of resistance in multidrug resistance protein (MRP1)-overexpressing cells by LY329146.

The benzothiophene LY329146 reverses the drug resistance phenotype in multidrug resistance protein (MRP1)-overexpressing cells when dosed in combination with MRP1-associated oncolytics doxorubicin and vincristine. Additionally, LY329146 inhibited MRP1-mediated uptake of the MRP1 substrate LTC4 into membrane vesicles prepared from MRP1-overexpressing cells.

Open Innovation Drug Discovery (OIDD): A Potential Path to Novel Therapeutic Chemical Space

The continued development of computational and synthetic methods has enabled the enumeration or preparation of a nearly endless universe of chemical structures. Nevertheless, the ability of this chemical universe to deliver small molecules that can both modulate biological targets and have drug-like physicochemical properties continues to be a topic of interest to the pharmaceutical industry and academic researchers alike. The chemical space described by public, commercial, in-house and virtual compound collections has been interrogated by multiple approaches including biochemical, cellular and virtual screening, diversity analysis, and in-silico profiling. However, current drugs and known chemical probes derived from these efforts are contained within a remarkably small volume of the predicted chemical space. Access to more diverse classes of chemical scaffolds that maintain the properties relevant for drug discovery is certainly needed to meet the increasing demands for pharmaceutical innovation. The Lilly Open Innovation Drug Discovery platform (OIDD) was designed to tackle barriers to innovation through the identification of novel molecules active in relevant disease biology models. In this article we will discuss several computational approaches towards describing novel, biologically active, drug-like chemical space and illustrate how the OIDD program may facilitate access to previously untapped molecules that may aid in the search for innovative pharmaceuticals.

Chiral recognition of the angiotensin II (AT1) receptor by a highly potent phenoxyproline octanoamide

Abstract The synthesis and in vitro biological evaluation of a novel series of diastereomeric phenoxyproline octanoamides ( 3–h ) as angiotensin II (AT 1 ) receptor antagonists are reported.

Synthesis and pharmacological evaluation of a novel series of 5-aryl benzimidazole angiotensin II receptor antagonists

Abstract A novel series of benzimidazole angiotensin II (Ang II) receptor antagonists (4, 13, 5, 17) were synthesized and compared pharmacologically to the previously described imidazole analogues (1, 3a-b).