In vitro disintegration and dissolution studies of once-weekly copies of alendronate sodium tablets (70 mg) and in vivo implications

Curr Med Res Opin. 2008 Apr;24(4):1137-45. doi: 10.1185/030079908x280725. Epub 2008 Mar 10.


Objective: The aim of this study was to evaluate the in vitro disintegration and dissolution of 26 alendronic acid tablets (70 mg) on the market in Canada, Germany, the Netherlands, and the United Kingdom compared to the branded product (Fosamax).

Research design and methods: The disintegration and dissolution times were determined using the methods described in the United States Pharmacopeia 30 (USP 30). The disintegration of four orally disintegrating tablets (non-bisphosphonates) and branded film-coated risedronate sodium tablets were included for comparison.

Results: The mean disintegration times of the alendronic acid tablets ranged from 14 s for Pharmachemie (Netherlands) to 342 s (5.7 min) for Betapharm (Germany). The mean disintegration time of the branded product tablets ranged from 43 to 78 s. Six of the 26 companies market alendronic acid tablets with very rapid disintegration times which are similar to those of orally disintegrating tablets (non-bisphosphonates). The alendronic acid tablets with very rapid mean disintegration times are as follows: Pharmachemie (Netherlands), 14 s; Novopharm (Canada), 13-24 s; GRY-Pharma (Germany), 21 s; Juta Pharma (Germany), 30 s; APS/Teva (United Kingdom), 26 and 37 s; and Teva (UK), 14-29 s. Since there is no established disintegration time for alendronic acid tablets there can be no assurance that the copy tablets are equivalent to the branded product in terms of esophageal drug exposure. However, the in vitro disintegration times have not been correlated with in vivo disintegration and performance. The dissolution of all the bisphosphonate tablets was rapid with greater than 80% dissolved in 15 min and all products conformed to the USP 30 specification.

Conclusions: The dissolution of all alendronic acid tablets was rapid and complete and conformed to the established USP 30 specifications which should ensure adequate drug absorption from the copy products. However, copies of alendronic acid tablets are approved based on the results of single-dose bioavailability studies in healthy subjects and this is not adequate to establish similar disintegration characteristics.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alendronate / chemistry*
  • Biological Availability
  • Bone Density Conservation Agents / chemistry*
  • Canada
  • Diphosphonates / chemistry
  • Drugs, Generic*
  • Etidronic Acid / analogs & derivatives
  • Etidronic Acid / chemistry
  • Germany
  • Humans
  • In Vitro Techniques
  • Netherlands
  • Risedronic Acid
  • Tablets
  • Technology, Pharmaceutical
  • Time Factors
  • United Kingdom


  • Bone Density Conservation Agents
  • Diphosphonates
  • Drugs, Generic
  • Tablets
  • Risedronic Acid
  • Etidronic Acid
  • Alendronate