Yes and not on being done if one stops.

This is from pdr.net. Notice the half-life.

"Alendronate is administered orally. Transient distribution into soft tissue is rapidly followed by redistribution to bone or urinary excretion. Alendronate is approximately 78% bound to protein in human plasma. There is no evidence that any metabolism takes place. Once alendronate is bound to bone, the half-life is more than 10 years. Inhibition of bone resorption diminishes after completion of treatment, suggesting that not all the alendronate sequestered in bone is biologically active.
Bone resorption in individual remodeling units normally continues for approximately 2 weeks. Due to the long half-life of alendronate in the bone, weekly administration of alendronate should inhibit bone resorption and provide benefits on bone mass and strength to a similar extent as daily administration."