With the exception of the
possible development of a hypervitaminosis associated with high-dose
administra-tion of vitamin D2 or D3,. Allergic reactions
to the injection of calcitonin and PTH have occurred and chronic use of some
bisphosphonates has been associ-ated with the development of osteomalacia. The
princi-pal side effects of intravenous bisphosphonates are mild and include low-grade
fever and transient increases in serum creatinine and phosphate levels. Oral
bisphos-phonates are poorly absorbed and can cause esophageal and gastric
ulceration. They should be taken on an empty stomach; the individual must
remain upright for 30 minutes after ingestion.
Human rPTH (1-34) has been
produced by recombinant technologies, is now approved, and will soon be
available for the treatment of osteoporosis. It is given subcuta-neously, 25
g/day cyclically for 12 to 18 months, to in-crease bone density in individuals
with a history of frac-tures, severe osteopenia, or osteoporosis. PTHrP (1-36)
has also been synthesized and is in early clinical trials.
Calcitonin (Miacalcin, Miacalcin Nasal Spray) is a
syn-thetic 32–amino acid polypeptide that is identical to salmon calcitonin.
Salmon calcitonin is more potent than human calcitonin because of its higher
affinity for the human calcitonin receptor and its slower metabolic clearance.
Administration is by subcutaneous or intra-muscular injection or by nasal
spray. The absorption of the nasal form is slower than that of the parenteral
Vitamin D comes in many
formulations, including mul-tivitamin preparations, fish liver oils with or
without vi-tamin A, combinations with calcium salts, and vitamin D preparations
alone. Most forms of vitamin D contain ei-ther cholecalciferol (D3)
or ergocalciferol (D2).
Cholecalciferol is pure vitamin D3 derived from the ultraviolet conversion of 7-dehydrocholesterol to
chole-calciferol. Ergocalciferol (vitamin D2) is a sterol
derived from yeast and fungal ergosterol. Calcitriol
is the metabolically active vitamin D3 compound. Dihydrotachysterol is a synthetic
compound that may act somewhat more quickly than either vita-min D2
compounds are available for both oral and intravenous use. Some [alendronate (Fosamax) and etidronate (Didronel)] are used for os-teoporosis,
others [etidronate, tirludronate (Skelid),
risedronate (Actonel)] for Paget’s
disease, and yet oth-ers [pamidronate (Aredia),
zoledronic acid] for the hy-percalcemia of malignancy.