Men's Osteoporosis Support Group

Generic Fosamax approved

The FDA announced that generic Fosamax (alendronate) has been approved for distribution and sale in the United States. With generic Fosamax it is important that the pill form is easily swallowed and that it couldn't adhere to the esophageal surface since problems developed with Fosamax when it was first approved by the FDA in the round pill form which was used on a once-daily basis. This occasionally caused "pill esophagitis" if not taken with adequate water or if the individual did not remain upright until they ate. This esophagitis manifests as esophageal ulceration and inflammation at the site where adherence occurred. There are no studies of which I'm aware that have evaluated this new generic substitute for Fosamax as concerns how easily it can be swallowed, or how likely it is to adhere to the esophagus. There are, however, some European studies on generic Fosamax pills in use there, so I will highlight some of their findings.

Eur J Pharm Sci 2007 Aug;31(5):262-70. Comparative in vitro study of oesophageal adhesiveness of different commercial formulations containing alendronate. Shakweh M and others. PMID: 17576054. This was a laboratory (in vitro) study to evaluate the bioadhesive characteristics of alendronate generics marketed in Europe. This included the 10-mg variety that is taken once-daily as well as the preferred 70-mg dosage that is taken once-weekly. The important finding was that some of the generic formulations had cleavage rupture which left a large piece of the tablet mass attached to the mucosa. The authors conclude this was related to the inactive ingredients. The authors note: "The demonstrated differences in adhesiveness suggest that differences in oesophageal tolerance between Fosamax tablets and generics of sodium alendronate may exist."

Curr Med Res Opin. 2003;19(8):781-9. Disintegration/dissolution profiles of copies of Fosamax (alendronate). Epstein S and others. PMID: 14687450. The format in this study was to use the standard United States Pharmacopeia disintegration method to compare Fosamax to 13 copies manufactured outside the U.S. What they found was nine forms disintegrated faster than Fosamax and three disintegrated at least five-fold slower. Additionally one softgel capsule was variable. The ideal is to disintegrate at the same speed as Fosamax to duplicate its efficacy. Slower disintegration may reduce the effectiveness and faster disintegration could allow for esophageal irritation. A capsule form should not be used. The authors conclude: "Additional testing is warranted to evaluate the pharmacokinetics and clinical safety of these copies."

Ann Pharmacother. 2007 Jan;41(1):29-34. Brand versus generic alendronate gastrointestinal effects measure by resource utilization. Halkin H and others. PMID: 17190847. This study tracked the adverse reactions to the upper gastrointestinal tract (UGIT) in people who took either 10- or 70-mg Fosamax or a generic alendronate for three continuous months during 2001-2005, which included 6962 individuals. In the year before the study began the people had not taken alendronate nor had any GI problems. The incidence rates of new use of gastric medications, gastroenterology visits, endoscopies and hospital admissions were compared. Those taking generics appeared to have slightly worse results but the authors conclude: "We found insufficient evidence to indicate major differences in UGIT adverse effects related to use of daily generic, as compared to brand, alendronates." (Note there was no placebo group which would have been enlightening for comparison purposes. That is, how many people not taking any form of alendronate have a new incidence of UGIT during a three-month period?)

Editor's comments: In a previous Update, a study was cited which showed capsules can take almost eight times longer to transit the esophagus than an oval film-coated tablet. Thus that formulation should not be used for alendronate generics which are known to be inflammatory if they adhere in the esophagus. I would suggest before switching to a generic alendronate you try to find how the medication compared to brand-name Fosamax in studies that compared esophageal transit time, dissolution time, etc. These are important issues for Fosamax. And/or it might be smart to have some form of biochemical marker of bone resorption testing done, such as serum or urinary CTX. That is, a CTX test done before switching to generic should be done again in perhaps 3-6 months at which time you would expect roughly equal results if the generic is working as well as the brand did.

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