Two-year results of once-weekly Fosamax
The once-weekly 70-mg dosage of Fosamax to treat osteoporosis is relatively new. Studies showed that it was effective after one year of therapy, but longer-term studies are just now being published showing it is also effective after two years of therapy. See: J Bone and Miner Res 2002 Nov,17(11):1988-96, Two-year results of once-weekly administration of alendronate 70 mg for the treatment of postmenopausal osteoporosis. Greenspan SL and others, PMID 12412806. Twelve hundred fifty-eight postmenopausal women aged 42-95 with either osteoporosis (lumbar spine or femoral neck BMD at least 2.5 SDs below peak young adult mean) or prior vertebral or hip fracture were placed in one of three groups taking Fosamax (alendronate): Five hundred nineteen took 70-mg once-weekly , 369 took 35-mg twice-weekly, and 370 took 10-mg daily for two years in this double-blind study. Mean bone mineral density (BMD) increases from baseline at 24 months were 6.8%, 7.0%, and 7.4% in the lumbar spine and 4.1%, 4.3%, and 4.3% in the total hip in the once-weekly, twice-weekly, and daily dosage groups respectively. The authors conclude: "The 2-year results confirm the conclusion reached after 1 year that once-weekly alendronate is therapeutically equivalent to daily dosing, providing patients with a more convenient dosing option that may potentially enhance adherence to therapy". They also state, "All treatment regimens were well tolerated with a similar incidence of upper gastrointestinal (GI) adverse experiences." (Editor's comments. These results are not particularly surprising, however, anything to the contrary would have been. Still, it is good to know that this convenient form of therapy works as well long term as it does short term. Another interesting aspect is that incidence of upper gastrointestinal adverse experiences was similar in all three groups showing that if Fosamax is taking according to the directions it is safe with adverse events similar to placebo.)
Fosamax should be taken if total knee or hip replacement surgery is done
Recent studies have shown that Fosamax can be effective at preventing bone loss for reasons other than osteoporosis. After total hip arthroplasty (THA), or total knee arthroplasty (TKA), prosthetic hip or knee replacement surgery in layman's terms, there is often undesired bone loss around the implants, apparently because the implants shield the bone from stress. This loss of BMD can be quite significant, in fact, up to 44% one year after TKA. There are two recent articles discussing this problem which will be discussed. For the first of these, see J Bone Miner Res 2001 Nov;16(11)2126-31, Alendronate reduces periprosthetic bone loss after uncemented primary total hip arthroplasty: a prospective randomized study. Venesmaa PK and others, PMID 11697810. This six-month study had 13 THA patients separated into two groups with one group taking only 500 mg calcium daily and one group taking 10 mg Fosamax plus 500 mg calcium daily. The periprosthetic BMD decreased by 17.1% in the calcium-only group and by 0.9% (p=0.019) in the Fosamax group. The authors felt this was too short term of a study to draw long-term conclusions, but felt Fosamax may be beneficial for THA patients. For the second study, see also Acta Orthop Scand 1996 Aug;67(4):339-44, Decreased bone density of the distal femur after uncemented knee arthroplasty. A 1-year follow-up of 29 knees. Petersen MM and others, PMID: 8792735. This study looked at adaptive bone remodeling of the distal femur prospectively for one year after TKA. The authors looked at three different models of prosthetic devices while comparing two regions of interest (ROI 1 and ROI 2) near the prosthetic fixation pegs using dual photon absorptiometry (DPA). They found, "On average (n =29), a significant bone loss of 44% and 19% in ROI 1 and ROI 2, respectively, was reached at the 1-year follow-up, compared to the initial value." They concluded: "A decrease of this magnitude in BMD in the anterior distal femur 1 year after TKA may be an important determinant of periprosthetic fracture and later failure of the femoral component." (Editor's comments. The Petersen and others study didn't test the effectiveness of Fosamax or other approved osteoporosis therapy to reduce or eliminate the significant loss of BMD they found after TKA, which is unfortunate. It would be incorrect to apply the results of the Venesmaa and others study, but logically we can assume there might be similar improvement. Hopefully there will be a follow-up study to test this hypothesis. Until then, patients and physicians will have to decide if Fosamax is proper therapy before and after TKA or THA, and how long to continue the therapy if it is started. The bottom line from these studies appears to be that understanding that Fosamax might prevent a serious complication after the surgery could be extremely important to know, and something to discuss with your surgeon before having the THA or TKA done).