Methods of treating bone loss

Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...

Reexamination Certificate

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C514S254080, C514S419000

Reexamination Certificate

active

06239144

ABSTRACT:

SUMMARY OF THE INVENTION
Tachykinins are a family of peptides which share a common amidated carboxy terminal sequence. Substance P was the first peptide of this family to be isolated, although its purification and the determination of its primary sequence did not occur until the early 1970's.
Between 1983 and 1984 several groups reported the isolation of two novel mammalian tachykinins, now termed neurokinin A (also known as substance K, neuromedin L, and neurokinin &agr;), and neurokinin B (also known as neuromedin K and neurokinin &bgr;). See, J. E. Maggio,
Peptides
, 6 (Supplement 3):237-243 (1985) for a review of these discoveries.
Tachykinins are widely distributed in both the central and peripheral nervous systems, are released from nerves, and exert a variety of biological actions, which, in most cases, depend upon activation of specific receptors expressed on the membrane of target cells. Tachykinins are also produced by a number of non-neural tissues.
The mammalian tachykinins substance P, neurokmin A, and neurokinin B act through three major receptor subtypes, denoted as NK-1, NK-2, and NK-3, respectively. These receptors are present in a variety of organs.
Substance P is believed inter alia to be involved in the neurotransmission of pain sensations, including the pain associated with migraine headaches and with arthritis. These peptides have also been implicated in gastrointestinal disorders and diseases of the gastrointestinal tract such as inflammatory bowel disease. Tachykinins have also been implicated as playing a role in numerous other maladies, as discussed infra.
Tachykinins play a major role in mediating the sensation and transmission of pain or nociception, especially migraine headaches. see. e.g., S. L. Shepheard, et al.,
British Journal of Pharmacology
, 108:11-20 (1993); S. M. Moussaoui, et al.,
European Journal of Pharmacology
, 238:421-424 (1993); and W. S. Lee, et al.,
British Journal of Pharmacology
, 112:920-924 (1994).
In view of the wide number of clinical maladies associated with an excess of tachykinins, the development of tachykinin receptor antagonists will serve to control these clinical conditions. The earliest tachykinin receptor antagonists were peptide derivatives. These antagonists proved to be of limited pharmaceutical utility because of their metabolic instabilty.
Recent publications have described novel classes of non-peptidyl tachykinin receptor antagonists which generally have greater oral bioavailability and metabolic stability than the earlier classes of tachylinin receptor antagonists. Examples of such newer non-peptidyl tachykinin receptor antagonists are found in U.S. Pat. No. 5,491,140, issued Feb. 13, 1996; U.S. Pat. No. 5,328,927, issued Jul. 12, 1994; U.S. Pat. No. 5,360,820, issued Nov. 1, 1994; U.S. Pat. No. 5,344,830, issued Sep. 6, 1994; U.S. Pat. No. 5,331,089, issued Jul. 19, 1994; European Patent Publication 591,040 A1, published Apr. 6, 1994; Patent Cooperation Treaty publication WO 94/01402, published Jan. 20, 1994; Patent Cooperation Treaty publication WO 94/04494, published Mar. 3, 1994; Patent Cooperation Treaty publication WO 93/011609, published Jan. 21, 1993; Canadian Patent Application 2154116, published Jan. 23, 1996; European Patent Publication 693,489, published Jan. 24, 1996; and Canadian Patent Application 2151116, published Dec. 11, 1995.
It is known that even in the adult human, bone is subject to turnover. In certain locations, such as the internal auditory capsule, there is apparently no turnover after the organ is formed. In other locations, particularly in the central skeletal axis, the turnover appears to continue during adulthood. Bone turnover occurs on the surface of the existing bone matrix, which is composed of protein (mainly collagen) and minerals. Bone turnover is initiated with the destruction of bone matrix by osteoclasts. The osteclast is a multinucleated cell which secretes acid and proteolytic enzymes leading to the lysis of the collagen matrix protein and the release of minerals into the extracellular fluid compartment. Following this initial phase of bone destruction, or resorptive phase, formation of new bone protein matrix sets in. New bone proteins are deposited, and sometime later, minerals begin to be incorporated into the newly formed matrix. The formation of bone matrix and its subsequent mineralization are functions of osteoblasts, which are mononucleated cells. The formation phase is often followed by a period of inactivity (1,2). In vivo, resorption appears to be tightly coupled with formation (3) and bone turnover is thus a succession of events, the location of which is known as the Bone Metabolism Unit or the BMU. Osteoblasts and osteoclasts, the putative mediators of bone turnover are thought to belong to two distinct cell lineages. These two cell types are not preformed cells, but they differentiate from their precursors through cell activation.
Bone matrix can either be maintained by a cessation of bone turnover as for the bone of the internal auditory capsule, or by a balance between resorption and formation. In many studies on skeletal changes in relation to age, a gain in the total body bone volume is observed during the growth period and the skeletal mass readies a maximum during early adulthood. This gain is followed by a fall in bone volume with age. In females, a phase of more rapid bone loss often occurs during the perimenopausal period before a slower steadier phase. For this reason, bone loss in the female tends to be more severe than in the male. An understanding of bone balance in the BMU may thus be critical to understanding the pathogenesis of skeletal aging. In any case, mechanisms controlling bone turnover are complex and are not well understood at this time. The complexity of the control mechanisms has resulted in a variety of approaches to reducing bone loss.
Bone turnover can be regulated at two different stages. It can be regulated at the stage of the activation of precursor cells. Regulators of cellular activation can control not only the number of active BMU in the skeleton, but possibly also the number of osteoclasts and osteoblasts in an individual BMU. Bone turnover secondly can be regulated at the level of differentiated bone cells. The complexity of the bone cell system makes the separate study of these two levels of regulation difficult.
Regulators of bone cells appear to fall into two categories. The first type interacts with specific receptors on cell membranes. One class of these regulators acts through the adenylate cyclase system with the generation of intra-cellular cyclic AMP as the second messenger acting on the protein kinase K system. Parathyroid hormone (PTH) and calitonin (CT) belong to this class. A second class also interacts with a membrane receptor and results in the intracellular release of a molecule derived from phosphoinositides which in turn leads to an increase in intracellular calcium and activation of Kinase C. A third class involves interaction of the regulator with a cell surface receptor, but the second signal is generated by the receptor molecule itself with the subsequent activation of tyrosine Kinase. Many of the growth factors appear to act in this way (8-15). Regulators falling into the second category do not interact with a cell membrane receptor, but can cross the cell membrane to bind with a cytosolic receptor. The regulator is then transported across the nuclear membrane by the cytosolic receptor to interact with the DNA resulting in increased transcription of specific genes. Steroid hormones, including vitamin D, appear to act in this manner.
Many hormones stimulate the proliferation of osteoclasts. These include 1,25(OH)2D, PTH and prostaglandins. PTH and 1,25(OH)2D receptors in osteoclasts have apparently not yet been identified. These two hormones seem to have no effect on osteoclasts in culture. However, when osteoclasts are co-cultured with osteoblast-like cell lines, PTH and 1,25(OH)2D stimulate the proliferation of osteoclasts. IL-1 and TNF appear to act in a similar way as PTH and 1,2

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