A new patch product in clinical trials could provide a patient-friendly means of delivering the only drug treatment for osteoporosis that can actually replace lost bone, reports Phil Taylor.
Canada's Theratechnologies has just completed Phase I clinical trials of the patch, which delivers parathyroid hormone (PTH) using a transdermal technology developed by US drug delivery specialist Alza.
PTH is the only osteoporosis treatment on the market that rebuilds the bone lost as a result of the disease, but its use is limited by the fact that it must be delivered by subcutaneous injection. As a consequence, many patients prefer to receive treatment using alternative drug classes, such as the bisphosphonates, which can prevent bone breakdown and are orally available.
At present, the only PTH-type drug on the market its Eli Lilly's Forteo (teriparatide), although intranasal and oral versions are in clinical development. Theratechnologies' initial studies have shown that its patch can deliver PTH to the blood at level which rival those achieved with subcutaneous Forteo.
The preliminary results also showed that the patch had a positive effect on urinary cyclic AMP levels (cAMP), a marker of PTH's biological activity. Within two hours of administration, both the patch and Forteo showed increases in cAMP that suggested the hormone was exerting its intended effect in the body.
Changes were also observed for both routes of administration in other markers of PTH's biological activity, such as serum calcium. There were no serious adverse events reported for the patch group, and the systemic adverse events observed in both treatment groups are typical of what has been previously reported with PTH treatment.
Alza's Macroflux transdermal technology is at the heart of the new product. This incorporates a thin titanium screen with precision microprojections that, when applied to the skin, creates superficial pathways through the skin's dead barrier layer allowing transport of macromolecules. The technology is also being used in vaccine development, as a means of delivering protein antigens across the skin.
It is estimated that osteoporosis affects approximately 30 million people in the US, Europe and Japan.