Generic Drugs, What is Generic Drugs?
A generic drugs (generic drugs, short: generics) is a drug defined as "a drug product that is comparable
to brand reference listed drug product in dosage form, strength, route of administration, quality and performance
characteristics, and intended use." It has also been defined as a term referring to any drug marketed under its
chemical name without advertising.
Although they may not be associated with a particular company, generic drugs are subject to the regulations
of the governments of countries where they are dispensed.
Generic drugs are labeled with the name of the manufacturer and the adopted name (nonproprietary name) of the drug.
A generic drug must contain the same active ingredients as the original formulation.
According to the U.S. Food and Drug Administration (FDA), generic drugs are identical or within an acceptable
bioequivalent range to the brand-name counterpart with respect to pharmacokinetic and pharmacodynamic properties.
By extension, therefore, generics are considered (by the FDA) identical in dose, strength, route of administration, safety,
efficacy, and intended use.
The FDA's use of the word "identical" is very much a legal interpretation, and is not literal.
In most cases, generic products are available once the patent protections afforded to the original developer have expired.
When generic products become available, the market competition often leads to substantially lower prices for both
the original brand name product and the generic forms.
The time it takes a generic drug to appear on the market varies. In most countries of the world, patents give 20 years of
protection. However, many countries regions, e.g. the European Union and the USA  may grant up to 5 years of
additional protection for drugs (patent term restoration).
Prescriptions may be issued for drugs specifying only the chemical name, rather than a manufacturer's name; such a
prescription can be filled with a drug of any brand meeting the specification.
For example, a prescription for lansoprazole can be filled with generic lansoprazole, Prevacid, Helicid, Zoton,
Inhibitol, or Monolitum.
A generic drug of biological type (e.g. monoclonal antibodies), is different from chemical drugs because of its biological
nature and it is regulated under extended set of rules for it; see Biosimilars.
Generic drugs names are constructed using standardized affixes that separate the drugs between and within
classes and suggest the action of the drug.
Generic drugs are usually sold for significantly lower prices than their branded equivalents. One reason for the relatively
low price of generic medicines is that competition increases among producers when drugs no longer are protected
by patents. Companies incur fewer costs in creating generic drugs
(only the cost to manufacture, rather than the entire cost of development and testing) and are therefore able to maintain
profitability at a lower price. The prices are low enough for users in many less-prosperous countries to afford them.
Thailand has imported millions of doses of a generic version of the blood-thinning drug Plavix
(used to help prevent heart attacks), at a cost of 3 US cents per dose, from India, the leading manufacturer of generic drugs.
In the UK, generic drug pricing is controlled only by the reimbursement price. Beneath this, the price paid by chemists and
doctors is determined mainly by the number of licence holders, the sales value of the originator brand and the ease of
manufacture. A typical price decay graph will show a 'scalloped' curve, which usually starts out on the day of generic
launch at the brand price, and then falls as competition intensifies.
After some years, the graph typically flattens out at approximately 20% of the originator brand price.
In about 20% of cases, the price 'bounces', which means some licence holders withdraw from the market when
the selling price dips below their cost of goods. The price then rises for a while until they re-enter the market with new stock.
Generic manufacturers do not incur the cost of drug discovery. Sometimes, reverse-engineering is used to develop
bioequivalent versions to existing drugs. Generic manufacturers also do not bear the burden of proving the safety and
efficacy of the drugs through clinical trials, since these trials have already been conducted by the brand name company.
The average cost to brand-name drug companies of discovering and testing a new innovative drug
(with a new chemical entity) has been estimated to be as much as $800 million.
Merril Goozner estimates the true cost is closer to $100-$200 million.
Generic drug companies may also receive the benefit of the previous marketing efforts of the brand-name drug company,
including media advertising, presentations by drug representatives, and distribution of free samples.
Many drugs introduced by generic manufacturers have already been on the market for a decade or more, and may already
be well known to patients and providers (although often under their branded name).
For as long as a drug patent lasts, a brand name company enjoys a period of “marketing exclusivity” or monopoly, in
which the company is able to set the price of the drug at a level which maximizes profitability. The profit often greatly
exceeds the development and production costs of the drug.
This is partially offset by research and development of other drugs which do not make a profit.
The advantage of generic drugs to consumers comes in the introduction of competition, which prevents any single
company from dictating the overall market price of the drug. Competition is also seen between generic and name-brand
drugs with similar therapeutic uses when physicians or health plans adopt policies of preferentially prescribing generic drugs
as in step therapy.
With multiple firms producing the generic version of a drug, the profit-maximizing price generally falls to the ongoing cost of
producing the drug, which is usually much lower than the monopoly price.
Most nations require generic drug manufacturers to prove their formulation exhibits bioequivalence to the innovator product.
Bioequivalence, however, does not mean generic drugs must be exactly the same (“pharmaceutical equivalent”) as
their innovator product counterparts, as chemical differences may exist (different salt or ester - a “pharmaceutical alternative”).
Since the US Hatch-Waxman Act of 1984,
most small molecule drugs are accepted as bioequivalent if their pharmacokintic parameters of AUC and Cmax are
within the range of a 90% Confidence Interval of 80.00%-125.00%; most approved generics are well within this limit.
For more complex products, such as inhalers, patch delivery systems, liposomal preparation, or biosimilar products,
testing to show pharmacodynamic or clinical equivalence is a more complex challenge.
In Japan, Prime Minister Shinzo Abe is pushing for a bigger market share of generic drugs to solve the problem of
Health care system in Japan. However, the market penetration of generic medicines are more apparent in countries
with less advanced healthcare systems such as the case of emerging markets like the Philippines.
A 2009 Weill Cornell Medical College study concluded that patients switched to generic oxybutynin experienced a
degradation in therapeutic value: "When we looked at changes in [prostate-specific antigen] (PSA) levels among men on
Avodart switched to the generic formulation, we saw a greater than 0.75 ng/mL increase at 3 months in 34% of men.
That is an increase that
would ordinarily trigger a biopsy, but I put them back on the brand-name drug. The PSA came down in all cases, and none
of them needed a biopsy", Steven A. Kaplan said of the findings.
However, this finding is largely inconclusive for several reasons, namely (i) pharmaceutical companies regularly do not
publish trial results so there may well be unpublished studies that did not find this effect (i.e. Publication Bias),
the study was funded by GSK, and may suffer from Funding bias, (iii) the finding has not been reproduced in other studies,
and, perhaps most importantly, (iv) this was not a randomised-controlled trial and recorded effects may be statistical
artefacts, or results of the Nocebo effect.
In the United States Patent Issues
When a pharmaceutical company first markets a drug, it is usually under a patent that, until it expires, allows only the
pharmaceutical company that developed the drug (or its licensees) to sell it. Generic drugs can be produced without patent
infringement for drugs where: 1) the patent has expired, 2) the generic company certifies the brand company's patents
are either invalid, unenforceable or will not be infringed, 3) for drugs which have never held patents, or 4) in countries where
the drug does
not have current patent protection. Patent lifetime differs from country to country; typically an expired patent cannot be renewed.
In the U.S., patent extensions may be granted if changes are made; some pharmaceutical companies have sought extensions
on things as minor as changes to the shape and color of the pill; generic makers are excluded while the adjudication of the
extension is considered. A new version of the drug with significant changes to the compound could be patented, but this
requires new clinical trials. In addition, a patent on a changed compound does not prevent sales of the generic versions of
the original drug unless regulators take the original drug off the market, as happened in the case of terfenadine.
This allows the company to recoup the cost of developing that particular drug. After the patent on a drug expires, any
pharmaceutical company can manufacture and sell it; only manufacturing cost will be incurred, which is a small fraction
of the cost of original testing, development and marketing of the drug.
In the U.S., the Patient Protection and Affordable Care Act, which President Obama signed on March 23, 2010, authorized the
Food and Drug Administration to approve generic versions of biologic drugs and grant biologics manufacturers 12 years of
use before generics can be developed. This biosimilar products are usually protected by surrounding patents which may
also delay the time for their production.
When several top selling drugs go off-patent within a short period of time an interesting phenomenon called patent
cliff arises opening opportunities for generic drug manufacturers.
Approval Process and Generic Drugs
Enacted in 1984, the U.S. Drug Price Competition and Patent Term Restoration Act, informally known as the Hatch-Waxman
Act, standardized U.S. procedures for recognition of generic drugs. An applicant files an Abbreviated New Drug Application
(ANDA) with the Food and Drug Administration (FDA), and seeks to demonstrate therapeutic equivalence to a specified,
“reference listed drug”. When an ANDA is approved, the FDA adds the drug to its Approved Drug Products with Therapeutic
Equivalence Evaluations list, also known as the Orange Book, and annotates the list to show equivalence between the
listed drug and the approved generic. The FDA also recognizes drugs using the same ingredients with different
bioavailability, and divides them into therapeutic equivalence groups. For example, as of 2006, diltiazem hydrochloride
had four equivalence groups, all using the same active ingredient, but considered equivalent only within a group.
On October 4, 2007, FDA launched the Generic Initiative for Value and Efficiency, or GIVE.
GIVE will use existing resources to help FDA modernize and streamline the generic drug approval process. It also aims to
increase the number and variety of generic drug products available. Having more generic-drug options means more
cost-savings to consumers, as generic drugs cost about 30 percent to 80 percent less than brand name drugs.
In the United States, generic drug substances are named through review and recommendation of the United States Adopted
Names (USAN) Council.
The U.S. FDA offers a 180-day exclusivity period to generic drug manufacturers in specific cases.
During this period, only one (or sometimes a few) generic manufacturers can produce the generic version of a drug.
This exclusivity period is only used when a generic manufacturer argues that a patent is invalid or is not violated in
the generic production of a drug, and the period acts as a reward for the generic manufacturer who is willing to risk
liability in court and the cost of patent court litigation.
There is often contention around these 180-day exclusivity periods because a generic producer does not have to produce the
drug during this period and can file an application first to prevent other generic producers from selling the drug.
Recently, the purpose of the exclusivity "bonus" provided for by the Hatch-Waxman amendments was turned on its
head when the original patent holder, Cephalon, instituted patent infringement suits against all companies holding
generic exclusivity rights to
manufacture modafinil, the generic name for Cephalon's still-profitable stimulant drug, Provigil. "Settlement" of this suit with
Cephalon was hardly a risky endeavor for the generic manufacturers, as it was Cephalon which agreed to pay Provigil's
alleged infringers in excess of a billion dollars - if they agreed not to market generics for Provigil during their period of
exclusivity. In effect, Cephalon was able to extend its exclusive right to manufacture Provigil even though Cephalon's
patent for it had already run out.
Large pharmaceutical companies often spend millions of dollars protecting their patents from generic competition.
Apart from litigation, companies use other methods, such as reformulation or licensing a subsidiary (or another company),
to sell generics under the original patent. Generics sold under license from the patent holder are known as authorized
generics; they are not affected by the 180-day exclusivity period, as they fall under the patent holder's original drug application.
A prime example of how this works is simvastatin (Zocor), a popular drug created and manufactured by US-based
Merck & Co, which lost its US patent protection on June 23, 2006. India-based Ranbaxy Laboratories (at the 80 mg strength)
and Israel-based Teva Pharmaceutical Industries (at all other strengths) received 180-day exclusivity periods for simvastatin;
due to Zocor's popularity, both companies began marketing their products immediately after the patent expired.
However, Dr. Reddy's Laboratories also markets an authorized generic version of simvastatin under license from Zocor's
manufacturer, Merck & Co.; some packages of Dr. Reddy's simvastatin even show Merck as the actual manufacturer
and have Merck's logo on the bottom.
Brand-name drug companies have used a number of strategies to extend the period of market exclusivity on their
drugs, and prevent generic competition. This may involve aggressive litigation to preserve or extend patent protection
on their medicines, a process referred to by critics as “evergreening”. Patents are typically issued on novel
pharmacological compounds quite early in the drug development process, at which time the ‘clock’ to patent expiration
begins ticking. Later in the process, drug companies
may seek new patents on the production of specific forms of these compounds, such as single enantiomers of
drugs which can exist in both “left-handed” and “right-handed” forms, different inactive components in a drug salt,
or a specific hydrate form of the drug salt.
If granted, these patents ‘reset the clock’ on patent expiration. These sorts of patents may later be targeted for invalidation
(“paragraph IV certification”) by generic drug manufacturers.
Quality Standards Generic Drugs
In the U.S., the FDA must approve generic drugs just as innovator drugs must be approved.
The FDA requires the bioequivalence of the generic product to be between 80% and 125% of that of the innovator product.
This value range is part of a statistical calculation, and does not mean the FDA allows generic drugs to differ from the
brand name counterpart by up to 25 percent. FDA recently evaluated 2,070 human studies conducted between
1996 and 2007, which
compared the absorption of brand name and generic drugs into a person’s body; they were submitted to the FDA to support
approval of generics. The average difference in absorption into the body between the generic and the brand name was 3.5
percent, comparable to differences between two different batches of a brand name drug.
A physician survey in the US found only 17% of prescribing physicians correctly identified the USFDA's standards for
bioequivalency of generic drugs.
A latest development to address this issue enables interested doctors and consumers to check generic drug
interactions and outcomes detail to the specific drug and drug company.
The generic equivalent of warfarin has only been available under the brand name Coumadin in North America
until recently. Warfarin (either under the trade name or the generic equivalent) has a narrow therapeutic window
and requires frequent blood
tests to make sure patients do not have a subtherapeutic or a toxic level. A study performed in the Canadian province of
Ontario showed that replacing Coumadin with generic warfarin was safe.
In spite of the study, many physicians are not comfortable with their patients taking the branded generic equivalents.
In some countries (for example, Australia) where a drug is prescribed under more than one brand name, doctors may
choose not to allow the pharmacist to substitute a brand different from prescribed unless the consumer requests a
Generic versions of biologic drugs, or biosimilars, require additional tests to bioequivalency involving clinical trials for
immunogenicity. These products cannot be entirely identical due to the batch to batch variability and their intrinsic
biological nature and are governed by extra sets of rules by the FDA in the US and the EMA in Europe.
In 2007, North Carolina Public Radio's The People's Pharmacy "began collecting and reporting consumer complaints about
generic Wellbutrin" yielding unexpected effects.
Subsequently, Impax Laboratories's 300 mg extended-release bupropion hydrochloride tablets, marketed by Teva
Pharmaceutical Industries, were formally withdrawn from the U.S. market after being determined not bioequivalent
by the FDA in 2012.
Two women, each claiming to have suffered severe medical complications from a generic drug, lost their Supreme
Court appeal on June 23, 2011. In a 5-4 ruling, the justices found that generic drug companies do not share the same
level of responsibility as makers of brand-name equivalents and do not have to update their warning labels when
significant new risks emerge.
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