25 terms

Pharmacology: 62 Bone Mineral Homeostasis

MOA: recombinant PTH

USE: osteoporosis

PK: pulsatile dose stimulate bone formation-intermittent SC injection

AE: excess causes resorption
Cholecalciferol (Vitamin D3)
From precursor 7-dehydrocholesterol; gets converted to 25OH VitD3 and then 1a-hydroxylase in kidney converts to 1,25 DiOH VitD3

USE: added to nutritional supplement

AE: chronic overdose leads to hyperphosphatemia
Vitamin D2

USE: iAdded to Ca supplements and dairy products
Active form of Vitamin D; 1,25 Dihydroxy Vitamin D

MOA: acts by steroidal receptor

USE: secondary hyperparathyroidism in patients with Chronic Renal Disease and liver disease

AE: chronic overdose leads to hyperphosphatemia
1alpha hydroxy vitamin D2
19-nor-1,25 Dihydroxyvitamin
Vitamin D

USE: psoriasis (topical)

calciPotriol Psoriasis
USE: osteoporosis (increase bone mass and reduces spine fractures)

note: Calcitonin itself is not use; SALMON calcitonin is used (has longer half life and greater potency)

PK: injection, nasal spray
Calcium salts
Tamoxifen, Raloxifene (SERMs)
Estrogen (useful in preventing bone loss)

USE: Osteoporosis in post menopausal women

Given as hormonal replacement therapy

AE: Thromboembolism, Migraine, Increased risk of breast and endometrial cancer, hot flushes (tamo)

Tamoxifene: estrogen antagonisitic action in breast, while agonistic effect in bone and uterus (also used to tx. breast cancer)

Raloxifene: estrogen antagonistic action on breast and agonist at bone. Has NO estrogenic effect on endometrium
Etidronate (iv), Alendronate, Pamidronate (iv)

MOA: inhibit osteoclastic activity disrupting the mevalonate pathway decreasing osteoclast H+ATPase: reduces resorption and helps formation of hydroxyapatite.

oral bioavailability less than 10%

USE: osteoporosis, malignancy associated with hypercalcemia, paget's

AE: erosive esophagitis due to direct irritation to esophageal lining (take meds upright, increase fluid intake); osteonecrosis of jaw
MOA: Activates the calcium sensing receptors in parathyroid cells. Leading to suppression of PTH synthesis and release

USE: secondary hyperparathyroidism in Chronic Renal Disease; hyperparathyroidism in patients with parathyroid carcinoma

AE: Hypocalcemia, decreased bone cell activity (adynamic bone disease)
MOA: binds to Ph binding site in GIT tract and decreases the absorption because it forms an insoluble complex (prevents hyperphosphatemia)

USE: patients with CRF
Chronic exposure can lead to new bone synthesis which is denser but brittle
Gallium nitrate
MOA: Inhibits bone resorption

USE: cancer realted hypercalcemia

AE: Nephrotoxic
Plicamycin (mithracin)
cytotoxic anticancer drug

USE: cancer related hypercalcemia

AE: Thrombocytopenia, Hepatic and renal toxicity
MOA: decrease the excretion of calcium by increasing reabsorption

USE: prevent renal stone formation; Treatment: hypertension in osteoporosis patient
increase osteoclast and osteoblast activity in bone via ligand RANK (TNF cytokine)

PTH couples Gs receptors to increase cAMP in bone and renal tubular cells

High levels of PTH present continously causes subperiosteal bone resorption
Vitamin D
acts by activatin steroidal nuclear receptor (hormonal)

Deficiency causes rickets in childrena nd osteomalacia in adults

USE: osteoporosis, chronic renal failure, nutritional rickets due to inadequate dietary intake, chronic liver disease

AE: chronic overdose leads to hyperphosphatemia
Drugs causing osteoporosis
corticosteroids, heparin, lithium, anastrazole, chronic alcohol use
Drugs causing osteomalacia
Phenytoin, etidronate (more than 12 mo. use)
Treatment of hypercalcemia
furosemide and saline infusion; bisphosphonates
Treatment of osteoporosis
Smoking cessation; calcium and vitamin D supplementation, bisphosphonates, SERMs, Teriparatide