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Delivery of Ovarian Hormones for Bone Health
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
This targeting approach does not require the use of liposome or other nanoparticles. The targeting motif can also be directly conjugated to drugs of interest such as estrogen. For example, tetracyclines are known to have high binding affinity to hydroxyapatite.58,141 Tetracycline and tetracycline analogs have been used for conjugation to estrogen to improve bone targeting selectivity to bone compared to nontarget tissues that would be susceptible to estrogen effects, such as uterus.110 Similarly, estrogens have also been conjugated to bisphosphonates. As described above, the bisphosphonates are a first-line treatment for osteoporosis. One reason that the bisphosphonates are successful in slowing the effects of osteoporosis through their antiresorptive effects is due to their high binding capacity for bone. Bisphosphonates can persist in bone tissue for months or years after deposition, likely due to their chemical similarity to hydroxyapatite.162 Given their beneficial effects when given in conjunction with hormone therapy,163,164 it is rational to use the bisphosphonates as targeting motifs to improve localization of hormone therapy, potentially providing the benefits of both with a greater degree of selectivity.17,108
Synthetic Approaches to Inhibitors of Isoprenoid Biosynthesis
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Pedro Merino, Loredana Maiuolo, Ignacio Delso, Vincenzo Algieri, Antonio De Nino, Tomas Tejero
Bisphosphonates are also classified into three generations depending when they were developed. Typical examples of first generation bisphophonates are etidronate (3) and cloronate (4). Their mechanism of action consists of being incorporated to non-hydrolyzable analogues of ATP, inducing osteoclast apoptosis (Fig. 2.3) (Nishida et al., 2003; Reszka and Rodan, 2003). Bisphosphonates clinically used for the treatment of bone disorders.
60)
Published in Sourav Bhattacharjee, Principles of Nanomedicine, 2019
A bisphosphonate derivative of C60 was synthesized in order to treat osteoporosis, where bones in the body, especially spine, hip, and wrist joints, become prone to fractures due to lack of bony mass (hydroxyapatite [HAp]) produced by the osteoblasts or higher bone resorption by the osteoclasts. Bisphosphonates are an established therapeutic strategy in osteoporosis and act by decreasing bone resorption due to inhibition of the osteoclasts. Typically, osteoporotic bones exhibit high metabolic activity, and a targeted delivery of bisphosphonates to such sites will cause improvement and is also expected to mitigate its side effects, such as gastric irritation and bone pain. The bisphosphonate conjugate C60(OH)16AMBP (Fig. 5.13), that is, 4,4-bisphosphono-2-(polyhydroxyl-1,2-dihydro1,2-methanofullerene[60]-61-carboxamido)butyric acid showed decent affinity (1 μM) toward HAp and curtailed its mineralization by half in vitro [56]. Another polyhydroxylated derivative, C60(OH)30, also reduced mineralization of HAp by 28%. It was shown in rat models that fullerenols can induce osteogenesis by eliminating ROS [57, 58].
The opportunity of using alloplastic bone augmentation materials in the maxillofacial region– Literature review
Published in Particulate Science and Technology, 2019
Simion Bran, Grigore Baciut, Mihaela Baciut, Ileana Mitre, Florin Onisor, Mihaela Hedesiu, Avram Manea
Osteoclasts are multinucleated cells that play the main role in bone resorption. They are only cells that destroy and resorb bone. Abnormal increase in osteoclast function leads to bone diseases such as osteoporosis (where resorption exceeds formation decreasing bone density and increasing fracture rate). In other pathologic conditions (e.g., bone metastases and inflammatory arthritis) abnormal osteoclast activity results in periarticular erosions and painful osteolytic lesions (Hellstein et al. 2011). This imbalance between resorption and formation of the bone is frequently treated with drugs called bisphosphonates which decrease osteoclast activity. Although their benefits considerably outweigh the risks, one side effect must be noted: the risk of BRONJ (Bisphosphonate-Related Osteonecrosis of the Jaw). This is why, the practitioner that performs any type of bone surgery must be aware of present bisphosphonate therapy and even distant history of such treatment (Charles and Aliprantis 2014).