26 with 200 mg of 5-CNAC, 16 patients were randomized to receive up to six regimens of rhPTH (1–34) or 2.5 or 5 mg of oral hPTH (1–34) with 100 or 200 mg of 5-CNAC, and treatments were administered for at least 6 days [28]. They reported all doses of the oral PTH were well absorbed and serum concentrations increased in a dose-dependent man- ner. The dose of PTH (1–34) of 2.5 or 5 mg combined with the oral enhancer CNAC at 200 mg had an area under the curve that was very similar to rhPTH (1–34) given by subcutaneous injection. The side effects of rhPTH (1–34) given by subcutaneous injections can be hypercalcemia; however; in this phase 1 study, ionized calcium remained within normal limits for all evaluated doses. Adverse events reported that resulted in study subjects withdrawing from the study were symptomatic hypotension (n = 3 from the PTH [1-34] at 2.5 or 5 mg with 200-mg CNAC; n = 1 rhPTH [1-34]; n = 1 placebo), three withdrew from pro- longed vomiting (5-mg PTH [1–34] and 200-mg CNAC), and symptomatic but unconfirmed hypercalcemia (n = 1 from the PTH [1–34] at 2.5 mg with 100-mg CNAC) [28]. This novel oral delivery system for hPTH (1–34) combined with an absorption enhancer CNAC appears to show promise for treating osteoporosis. Additional studies and refinement of the dosing regimen appear warranted to enhance the use of this novel technology. Parathyroid Hormone–Related Protein Parathyroid hormone–related protein (PTHrP) is a hormone that is closely related to another hormone discovered in the 1920s named parathyroid hormone (PTH). Similar to PTH, PTHrP is also a hormone that regulates calcium metabolism. PTH has been shown to be effective in treating osteoporosis in animals and humans [29]. PTHrP has been shown to be effective in treating osteoporosis in laboratory animals, and there are strong scientific reasons to think that it may be effective in humans also [30]. A study of PTHrP (1–36) was performed to determine if it could increase bone mass in postmenopausal women with osteoporosis when adminis- tered daily by subcutaneous injection for 3 months [31]. The double-blind, placebo-controlled, randomized clini- cal study enrolled 16 postmenopausal women with osteo- porosis between 50 and 75 years of age [31]. All had been on hormone replacement therapy for an average of 8 years and still had osteoporosis. Women who had been taking any other type of osteoporosis medication were excluded from the study. Half of the participants received a self- administered injection of PTHrP and the other half received a placebo. The patients were followed up for 3 months and the participants tolerated the treatment without developing hypercalcemia, hypotension, nausea, flushing, or other adverse effects. The lumbar spine BMD increased by Curr Osteoporos Rep (2010) 8:23–27 4.7% during the 3-month treatment period, a larger increase in bone gain that is usually observed with the available antiresorptive osteoporosis medications. Even though the study was designed as a pilot, the results were surprisingly more favorable than expected, and larger studies of longer duration are needed to elucidate the full potential of this bone-building agent and if the increase in bone mass can reduce incident fracture risk. Conclusions We now have a diverse menu of osteoporosis therapies including both antiresorptive and one anabolic therapy (teriparatide). Current research suggests that in the future we may have multiple different anabolic therapies such as sclerostin, PTHrP, and other potential molecules, and alternate delivery systems for administration. The therapies may have orthopedic benefits in terms of fracture healing and fusions. The future of anabolic therapies looks bright. Disclosure No potential conflicts of interest relevant to this article were reported. Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which per- mits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. References Papers of particular interest, published recently, have been highlighted as follows: Of major importance 1. van Amerongen R, Nusse R. Towards an integrated view of Wnt signaling in development. Development 2009;136:3205–14. 2. Hoeppner LH, Secreto FJ, Westendorf JJ. 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