Generic drugs contain the same active ingredients and are equivalent to their brand name counterparts. They are allowed for sale after the original drug patent expires. Generics are usually cheaper than brands because generic manufacturers don't have the same research and development costs as brand manufacturers. The FDA requires generics to have the same clinical effects as their brand versions.

1. Generic Drugs
A generic drug is a pharmaceutical drug that has the same chemical substance as
the drug that was originally developed, patented and innovated. Generic drugs are
allowed for sale after the expiry of the patent of the original drugs. Because the
active chemical substance is the same, the medical profile of generics is believed to
be equivalent in performance. The generic drug has the same active pharmaceutical
ingredient (API) as the original, but it may differ in characteristics such as
manufacturing process,formulation, excipient, color, taste, and packaging.
Although they may not be associated with a particular company, generic drugs are
usually subject to government regulations in the countries in which they are
dispensed. They are labeled with the name of the manufacturer and a generic
nonproprietary name such as the United States Adopted Name or international
nonproprietary name of the drug. A generic drug must contain the same active
ingredients as the original brand name formulation. The U.S. Food and Drug
Administration (FDA) requires generics to be identical to or within an
acceptable bioequivalent range of their brand name counterparts, with respect
to pharmacokinetic and pharmacodynamics properties. (The FDA's use of the word
"identical" is a legal interpretation, not literal.)
Biopharmaceuticals, such as monoclonal antibodies, differ biologically from small
molecule drugs. Bio similars have active pharmaceutical ingredients that are
almost identical to the original product and are typically regulated under an
extended set of rules, but they are not the same since generic drugs as the active
ingredients are not the same as those of their reference products.
In most cases, generic products become available after the patent protections,
afforded to a drug's original developer, expire. Once generic drugs enter the
market, competition often leads to substantially lower prices for both the original
brand name product and its generic equivalents. In most countries, patents give 20
years of protection. However, many countries and regions, such as the European
Union and the United States, may grant up to five years of additional protection
("patent term restoration") if manufacturers meet specific goals, such as
conducting clinical trials for pediatric patients.
Manufacturers, wholesalers, insurers, and drug stores can all increase prices at
various stages of production and distribution. In 2014, according to an analysis by

2. the Generic Pharmaceutical Association, generic drugs accounted for 88% of the
4.3 billion prescriptions filled in the United States.
"Branded generics" on the other hand are defined by the FDA and NHS as
"products that are (a) either novel dosage forms of off-patent products produced by
a manufacturer that is not the originator of the molecule, or (b) a molecule copy of
an off-patent product with a trade name. Since the company making branded
generics can spend little on research and development, it is able to spend on
marketing alone, thus earning higher profits and driving costs down. For example,
the largest revenues of Ranbaxy, now owned by Sun Pharma, came from branded
generics.
What is a drug patent definition?
Medical Definition of patent medicine: a packaged nonprescription drug which is
protected by a trademark and whose contents are incompletely disclosed; also: any
drug that is a proprietary.
Patent medicines are NOT medicines that have been patented. They are instead
proprietary (i.e., "secret formula") and unproved remedies advertised and sold
directly to the public. The growth of the patent medicine industry was rooted in the
medical shortcomings of the early 19th century.
How long does a drug patent last in the US?
Now, patents protect drugs from copycat versions for 20 years after the drug is
invented. This is a bitter pill for pharmaceutical companies because it can
take eight years or more after invention to accumulate enough data to get a drug
past the U.S. Food and Drug Administration.

3. Are generic drugs safe?
Yes. The FDA requires that all drugs be safe and effective. Since generics use the
same active ingredients and are shown to work the same way in the body, they
have the same risks and benefits as their brand-name counterparts.
Brand Name
Branded medicines are medicines which have a name given to them by a company
for the purpose of advertising. Branded medicines may be the original
medicine developed by a company or several companies may make the same
generic medicine, to which each company gives its own brand name.
Why generic medicines are cheaper?
Generic makers don't face the same costs as manufacturers of brand-name drugs.
That's because the brand-name maker often invented the drug, a process that can
cost hundreds of millions of dollars. ... That is an enormous economic advantage
for these companies, which is why their drugs can be much cheaper.
What is a branded generic?
Generic drugs are frequently as effective as, but much cheaper than, brand-name
drugs.2 Many generic medicines are marketed using only the generic name and are
not given a brand name. A branded generic is the brand name given to a drug that
is bioequivalent to the original (innovator).
Is generic medicine less effective?
A generic medicine is the same as a brand-name medicine in dosage, safety,
effectiveness, strength, stability, and quality, as well as in the way it is taken and
should be used. The FDA Generic Drugs Program conducts a rigorous review to
make sure generic medicines meet these requirements.

4. Can pharmacist substitute generic drugs?
A pharmacist may substitute a therapeutically equivalent drug product listed in the
current state drug formulary. ... A pharmacist may substitute with a generic product
unless the FDA has determined that a drug product of the same generic name is not
bioequivalent to the prescribed brand name prescription medication.
Generic Drugs- Why is it important?
A generic drug is equivalent to the brand name drug. After a brand name drug is
developed after considerable amount of research and after the patent expires,
generic drugs can be manufactured and sold to customers at very cheap rates.
According to the US FDA, “A generic drug is identical or bioequivalent to a brand
name drug in dosage, form, safety, strength, root of administration and intended
use.”
As we shall see, very often the cost difference is so much that even well to do
people cannot afford a branded drug while the generic version can be afforded.
Take the case of Novartis. It sells its anti cancer drug for treating chronic myeloid
leukemia ‘Gleevec’ for Rs. 1.2 lakh per month. The generic version costs Rs.
8000/month. The drug is out of patent in India and thus the generic drug can be
sold.
Novartis is fighting a case for grant of patent on a new, crystalline salt form of the
anti cancer drug ‘Immatinib Mesylate’ which it sold under the brand name
Gleevec. A patent on this new form could provide another 20 year monopoly to
Novartis. Such practices are called evergreening of patent.

5. Reference:
1. https://www.google.com
2. http://greencleanguide.com/generic-drugs/