Reader's Question: I have been told that Fosamax is coming out in generic form. I have been taking a brand name osteoporosis drug (in the same drug class) for numerous years with good results. Should I switch?
The first thing one must understand is what exactly is a generic medication. Pharmaceutical companies spend many years developing new drugs. They may file a patent that allows them to be the only one that can produce this drug for 20 years from the date of submission (not from the date of U.S. Food and Drug Administration (FDA) approval). This allows them to make a significant profit, taking into account the financial risks the company often has to take. These risks can often be very high, as the cost of developing some drugs can be hundreds of millions of dollars, with studies finding unexpected side effects, lack of efficacy and then, even after approval, failure of the drug to generate demand. When the patent expires, other drug manufacturers, often the original drug manufacturer themselves, apply to the FDA to produce a generic version.
Requirements for Generic Drugs
To gain FDA approval, a generic drug must:
- contain the same active ingredients as the innovator drug (inactive ingredients may vary)
- be identical in strength, dosage form, and route of administration
- have the same use indications
- be bioequivalent
- meet the same batch requirements for identity, strength, purity, and quality
- be manufactured under the same strict standards of FDA's good manufacturing practice regulations required for innovator products 
In most cases, the availability of equivalent generics is a great benefit to the public as the cost of the drug finally becomes affordable and in reach of many who could not take these before. However, one must be aware of the above FDA requirements and understand what they mean.
- While the active ingredients are the same, the inactive ones may vary. This can be a problem if one can tolerate the brand name but not the generic one. There can also be variations in the different generic brands as someone may tolerate one generic but not another. It may be best to stick to the same generic brand and not switch between the different available generics.
- While the drugs may be "identical in strength and dosage", the pills may look different, i.e. size, color or shape or have a different outside coating. These can often confuse people and cause medication errors or affect tolerability.
- While drugs must be bioequivalent, the FDA allows a variation of 20% of bioavailability. This is a range from 80% - 125%, where there is considered to be no statistically significant difference. oavailability is used to describe the amount of a dose of medication, which after being taken, arrives unchanged in the blood stream. 
I think the release of generic Fosamax is a big benefit to the consumer/patient. It will help many people who stopped, or never started, their osteoporosis medication due to the price, be able to afford a necessary medication and start to protect their bones.
When deciding to change to a generic there are some things to consider, should one switch brands if....
- they are tolerating one drug without difficulties or adverse reactions?
- it appears that the drug is working (in this case, increased bone density or/and lack of fractures)?
- there is thought to be a difference in drug efficacy?
- the drug being switched to may be less absorbed (i.e within the 20% of the standard FDA's range)?
I think the decision to change to a generic drug must be discussed carefully with your physician and all considerations based on the patient's personal history must be taken into account.
 FDA web site: http://www.fda.gov/cder/ogd/
 FDA web site: http://www.fda.gov/cder/guidance/5356fnl.pdf