Purinethol (Mercaptopurine)

What is a "Generic" medication/drug?

Generic drugs are medications that have the comparable medicinal ingredients as the original brand name drug, but which are generally cheaper in price. Nearly 1 in 3 drugs dispensed are "generic". They undergo comparative testing to ensure that they are the same as their "brand" counterparts in:

• Active Ingredient (e.g. "Pravastatin" is the active ingredient in brand name Pravachol)
• Dosage (e.g. 10 mg of the active ingredient)
• Safety (e.g. same or similar side effects, drug interactions)
• Strength
• Quality
• Performance (e.g. 10 mg of a "generic" can be substituted for 10 mg of the "brand" and have the same therapeutic result)
• Intended use (e.g. both "generic" and "brand" would be prescribed for the same conditions)

What this means is that "generic" medications can be used as a substitute of their brand equivalents with comparable therapeutic results. There are a few exceptions (examples are outlined at the end of this page) and as always you should consult your physician before switching from a brand name medications to a generic or vice versa.

What differences are there between generic and brand?

While generics and brand equivalent drugs contain comparable active ingredients, they may be different in the following ways:

• Color
• Shape
• Size
• Cost
• Appearance (e.g. the scoring or markings)

The color, shape and size of the medication come from the fillers that are added to the active ingredients to make the drug. These fillers that are added to the drug have no medical use and do not to change the effectiveness of the final product. A generic drug must contain comparable active ingredients and must be comparable in strength and dosage to the original brand name equivalent. Generic drugs can be more cost effective than purchasing the brand name.

Why do generics cost less than the brand name equivalents?

When a new drug is "invented", the company that discovered it has a patent on it that gives them the exclusive production rights for this medication. Once the patent expires in a country, other companies can bring the product to market under their own name. This patent prevents other companies from copying the drug during that time so they can earn back their Research and Development costs through being the exclusive supplier of the product. After the patent expires however, other companies can develop a "generic" version of the product. These versions generally are offered at much lower prices because the companies do not have the same development costs as the original company who developed the medication.

The main thing to realize here though is that the two products are therapeutically comparable. They may look different, and be called something different, but they are required to be have the same active ingredient.

How are Generic drugs tested to ensure quality and efficacy?

The two most generally accepted methods to prove the safety of a generic version of a drug are to either repeat most of the chemistry, animal and human studies originally done, or to show that the drug performs comparably with the original brand name drug. This second option is called a "comparative bioavailability" study. During this type of study, volunteers are given the original drug, and then separately later the generic drug. The rates at which the drug is delivered to the patient (into their blood stream or otherwise absorbed) are measured to ensure they are the same. Because the same active ingredient is used the major concern is just that it delivers the common chemical(s) at the same rate so that they have the same effect. Please note that the methods that the manufacturers use may vary from country to country.