FDA’s Drug Review Process
BY DR ANTHONY CRASTO
How Drugs are Developed and Approved
The mission of FDA’s Center for Drug Evaluation and Research (CDER) is to ensure that drugs marketed
in this country are safe and effective. CDER does not test drugs, although the Center’s Office of Testing
and Research does conduct limited research in the areas of drug quality, safety, and effectiveness.
CDER is the largest of FDA’s five centers. It has responsibility for both prescription and nonprescription
or over-the-counter (OTC) drugs. For more information on CDER activities, including performance of drug
reviews, post-marketing risk assessment, and other highlights, please see the CDER Update: Improving
Public Health Through Human Drugs The other four FDA centers have responsibility for medical and
radiological devices, food, and cosmetics, biologics, and veterinary drugs.
Some companies submit a new drug application (NDA) to introduce a new drug product into the U.S.
Market. It is the responsibility of the company seeking to market a drug to test it and submit evidence that
it is safe and effective. A team of CDER physicians, statisticians, chemists, pharmacologists, and other
scientists reviews the sponsor’s NDA containing the data and proposed labeling.
The section below entitled From Fish to Pharmacies: The Story of a Drug’s Development, illustrates how
a drug sponsor can work with FDA’s regulations and guidance information to bring a new drug to market
under the NDA process.
From Fish to Pharmacies: A Story of Drug Development
Osteoporosis, a crippling disease marked by a wasting away of bone mass, affects as many as 2 million
American, 80 percent of them women, at an expense of $13.8 billion a year, according to the National
Osteoporosis Foundation., The disease may be responsible for 5 million fractures of the hip, wrist and
spine in people over 50, the foundation says, and may cause 50,000 deaths. Given the pervasiveness of
osteoporosis and its cost to society, experts say it is crucial to have therapy alternatives if, for example, a
patient can’t tolerate estrogen, the first-line treatment.
Enter the salmon, which, like humans, produces a hormone called calcitonin that helps regulate calcium
and decreases bone loss. For osteoporosis patients, taking salmon calcitonin, which is 30 times more
potent than that secreted by the human thyroid gland, inhibits the activity of specialized bone cells called
osteoclasts that absorb bone tissue. This enables bone to retain more bone mass.
Though the calcitonin in drugs is based chemically on salmon calcitonin, it is now made synthetically in
the lab in a form that copies the molecular structure of the fish gland extract. Synthetic calcitonin offers a
simpler, more economical way to create large quantities of the product.
FDA approved the first drug based on salmon calcitonin in an injectable. Since then, two more drugs, one
injectable and one administered through a nasal spray were approved. An oral version of salmon
calcitonin is in clinical trials now. Salmon calcitonin is approved only for postmenopausal women who
cannot tolerate estrogen, or for whom estrogen is not an option.
How did the developers of injectable salmon calcitonin journey “from fish to pharmacies?”
After obtaining promising data from laboratory studies, the salmon calcitonin drug developers took the
next step and submitted an Investigational New Drug (IND) application to CDER. The IND Web
page explains the need for this application, the kind of information the application should include, and the
Federal regulations to follow.
Once the IND application is in effect, the drug sponsor of salmon calcitonin could begin their clinical
trials. After a sponsor submits an IND application, it must wait 30 days before starting a clinical trial to
allow FDA time to review the prospective study. If FDA finds a problem, it can order a “clinical hold” to
delay an investigation, or interrupt a clinical trial if problems occur during the study.
Clinical trials are experiments that use human subjects to see whether a drug is effective, and what side
effects it may cause. The Running Clinical Trials Webpage provides links to the regulations and
guidelines that the clinical investigators of salmon calcitonin must have used to conduct a successful
study, and to protect their human subjects.
The salmon calcitonin drug sponsor analyzed the clinical trials data and concluded that enough evidence
existed on the drug’s safety and effectiveness to meet FDA’s requirements for marketing approval. The
sponsor submitted a New Drug Application (NDA) with full information on manufacturing specifications,
stability and bioavailablility data, method of analysis of each of the dosage forms the sponsor intends to
market, packaging and labeling for both physician and consumer, and the results of any additional
toxicological studies not already submitted in the Investigational New Drug application. The NDA Web
page provides resources and guidance on preparing the NDA application, and what to expect during the
New drugs, like other new products, are frequently under patent protection during development. The
patent protects the salmon calcitonin sponsor’s investment in the drug’s development by giving them the
sole right to sell the drug while the patent is in effect. When the patents or other periods of exclusivity on
brand-name drugs expire, manufacturers can apply to the FDA to sell generic versions. TheAbbreviated
New Drug Applications (ANDA) for Generic Drug Products Webpageprovides links to guidances, laws,
regulations, policies and procedures, plus other resources to assist in preparing and submitting
Bringing Nonprescription Drug Products to the Market Under an OTC Monograph
OTC drugs can be brought to the market following the NDA process as described above or under an OTC
monograph. Each OTC drug monograph is a kind of “recipe book” covering acceptable ingredients,
doses, formulations, labeling, and, in some cases, testing parameters. OTC drug monographs are
continually updated to add additional ingredients and labeling as needed. Products conforming to a
monograph may be marketed without FDA pre-approval. The NDA and monograph processes can be
used to introduce new ingredients into the OTC marketplace. For example, OTC drug products previously
available only by prescription are first approved through the NDA process and their “switch” to OTC status
is approved via the NDA process. OTC ingredients marketed overseas can be introduced into the U.S.
market via a monograph under a Time and Extent Application (TEA) as described in 21 CFR 330.14. For
a more thorough discussion of how OTC drug products are regulated visit FDA laws, regulations and
guidances that affect small business. Information is also provided on financial assistance and incentives
that are available for drug development.
CDER Small Business and Industry Assistance (CDER SBIA)
Drug sponsors which qualify as small businesses can take advantage of special offices and programs
designed to help meet their unique needs. The CDER Small Business and Industry Assistance (CDER
SBIA) Webpage provides links to FDA laws, regulations and guidances that affect small business.
Information is also provided on financial assistance and incentives that are available for drug
The path a drug travels from a lab to your medicine cabinet is usually long, and every drug takes a unique
route. Often, a drug is developed to treat a specific disease. An important use of a drug may also be
discovered by accident.
For example, Retrovir (zidovudine, also known as AZT) was first studied as an anti-cancer drug in the
1960s with disappointing results. Twenty years later, researchers discovered the drug could treat AIDS,
and Food and Drug Administration approved the drug, manufactured by GlaxoSmithKline, for that
purpose in 1987.
Most drugs that undergo preclinical (animal) testing never even make it to human testing and review by
the FDA. The drugs that do must undergo the agency’s rigorous evaluation process, which scrutinizes
everything about the drug–from the design of clinical trials to the severity of side effects to the conditions
under which the drug is manufactured.
Investigational New Drug Application (IND)–The pharmaceutical industry sometimes seeks advice
from the FDA prior to submission of an IND.
Sponsors–companies, research institutions, and other organizations that take responsibility for
developing a drug. They must show the FDA results of preclinical testing in laboratory animals and what
they propose to do for human testing. At this stage, the FDA decides whether it is reasonably safe for the
company to move forward with testing the drug in humans.
Clinical Trials–Drug studies in humans can begin only after an IND is reviewed by the FDA and a
local institutional review board (IRB). The board is a panel of scientists and non-scientists in
hospitals and research institutions that oversees clinical research.
IRBs approve the clinical trial protocols, which describe the type of people who may participate in the
clinical trial, the schedule of tests and procedures, the medications and dosages to be studied, the length
of the study, the study’s objectives, and other details. IRBs make sure the study is acceptable, that
participants have given consent and are fully informed of their risks, and that researchers take
appropriate steps to protect patients from harm.
Phase 1 studies are usually conducted in healthy volunteers. The goal here is to determine what the
drug’s most frequent side effects are and, often, how the drug is metabolized and excreted. The
number of subjects typically ranges from 20 to 80.
Phase 2 studies begin if Phase 1 studies don’t reveal unacceptable toxicity. While the emphasis in
Phase 1 is on safety, the emphasis in Phase 2 is on effectiveness. This phase aims to obtain preliminary
data on whether the drug works in people who have a certain disease or condition. For controlled trials,
patients receiving the drug are compared with similar patients receiving a different treatment–usually an
inactive substance (placebo), or a different drug. Safety continues to be evaluated, and short-term side
effects are studied. Typically, the number of subjects in Phase 2 studies ranges from a few dozen to
At the end of Phase 2, the FDA and sponsors try to come to an agreement on how large-scale
studies in Phase 3 should be done. How often the FDA meets with a sponsor varies, but this is one
of two most common meeting points prior to submission of a new drug application. The other most
common time is pre-NDA–right before a new drug application is submitted.
Phase 3 studies begin if evidence of effectiveness is shown in Phase 2. These studies gather more
information about safety and effectiveness, studying different populations and different dosages and
using the drug in combination with other drugs. The number of subjects usually ranges from several
hundred to about 3,000 people.
Postmarket requirement and commitment studies are required of or agreed to by a sponsor, and are
conducted after the FDA has approved a product for marketing. The FDA uses postmarket
requirement and commitment studies to gather additional information about a product’s safety, efficacy, or
New Drug Application (NDA)–This is the formal step a drug sponsor takes to ask that the FDA
consider approving a new drug for marketing in the United States. An NDA includes all animal and
human data and analyses of the data, as well as information about how the drug behaves in the body and
how it is manufactured
When an NDA comes in, the FDA has 60 days to decide whether to file it so that it can be reviewed.
The FDA can refuse to file an application that is incomplete. For example, some required studies may be
missing. In accordance with the Prescription Drug User Fee Act (PDUFA), the FDA’s Center for Drug
Evaluation and Research (CDER) expects to review and act on at least 90 percent of NDAs for standard
drugs no later than 10 months after the applications are received. The review goal is six months for
priority drugs. (See “The Role of User Fees.”)
“It’s the clinical trials that take so long–usually several years,” says Sandra Kweder, M.D., deputy
director of the Office of New Drugs in the CDER. “The emphasis on speed for FDA mostly relates to
review time and timelines of being able to meet with sponsors during a drug’s development,” she says.
Drug Approval Process Infographic
Drug Review Steps Simplified
1. Preclinical (animal) testing.
2. An investigational new drug application (IND) outlines what the sponsor of a new drug
proposes for human testing in clinical trials.
3. Phase 1 studies (typically involve 20 to 80 people).
4. Phase 2 studies (typically involve a few dozen to about 300 people).
5. Phase 3 studies (typically involve several hundred to about 3,000 people).
6. The pre-NDA period, just before a new drug application (NDA) is submitted. A common time
for the FDA and drug sponsors to meet.
7. Submission of an NDA is the formal step asking the FDA to consider a drug for marketing
8. After an NDA is received, the FDA has 60 days to decide whether to file it so it can be
9. If the FDA files the NDA, an FDA review team is assigned to evaluate the sponsor’s research
on the drug’s safety and effectiveness.
10. The FDA reviews information that goes on a drug’s professional labeling (information on how
to use the drug).
11. The FDA inspects the facilities where the drug will be manufactured as part of the approval
12. FDA reviewers will approve the application or issue a complete response letter.
Supplemental Information About the Drug Approval
Though FDA reviewers are involved with a drug’s development throughout the IND stage, the official
review time is the length of time it takes to review a new drug application and issue an action letter, an
official statement informing a drug sponsor of the agency’s decision.
Once a new drug application is filed, an FDA review team–medical doctors, chemists, statisticians,
microbiologists, pharmacologists, and other experts–evaluates whether the studies the sponsor submitted
show that the drug is safe and effective for its proposed use. No drug is absolutely safe; all drugs have
side effects. “Safe” in this sense means that the benefits of the drug appear to outweigh the known risks.
The review team analyzes study results and looks for possible issues with the application, such as
weaknesses of the study design or analyses. Reviewers determine whether they agree with the sponsor’s
results and conclusions, or whether they need any additional information to make a decision.
Each reviewer prepares a written evaluation containing conclusions and recommendations about
the application. These evaluations are then considered by team leaders, division directors, and office
directors, depending on the type of application.
Reviewers receive training that fosters consistency in drug reviews, and good review practices
remain a high priority for the agency.
Sometimes, the FDA calls on advisory committees, who provide FDA with independent opinions and
recommendations from outside experts on applications to market new drugs, and on FDA
policies. Whether an advisory committee is needed depends on many things.
“Some considerations would be if it’s a drug that has significant questions, if it’s the first in its class,
or the first for a given indication,” says Mark Goldberger, M.D., a former director of one of CDER’s drug
review offices. “Generally, FDA takes the advice of advisory committees, but not always,” he says. “Their
role is just that–to advise.”Accelerated Approval
Traditional approval requires that clinical benefit be shown before approval can be granted.
Accelerated approval is given to some new drugs for serious and life-threatening illnesses that lack
satisfactory treatments. This allows an NDA to be approved before measures of effectiveness that would
usually be required for approval are available.
Instead, less traditional measures called surrogate endpoints are used to evaluate effectiveness.
These are laboratory findings or signs that may not be a direct measurement of how a patient feels,
functions, or survives, but are considered likely to predict benefit. For example, a surrogate endpoint
could be the lowering of HIV blood levels for short periods of time with anti-retroviral drugs.
Gleevec (imatinib mesylate), an oral treatment for patients with a life-threatening form of cancer
called chronic myeloid leukemia (CML), received accelerated approval. The drug was also approved
under the FDA’s orphan drug program, which gives financial incentives to sponsors for manufacturing
drugs that treat rare diseases. Gleevec blocks enzymes that play a role in cancer growth. The approval
was based on results of three large Phase 2 studies, which showed the drug could substantially reduce
the level of cancerous cells in the bone marrow and blood.
Most drugs to treat HIV have been approved under accelerated approval provisions, with the
company required to continue its studies after the drug is on the market to confirm that its effects on virus
levels are maintained and that it ultimately benefits the patient. Under accelerated approval rules, if
studies don’t confirm the initial results, the FDA can withdraw the approval.
Because premarket review can’t catch all potential problems with a drug, the FDA continues to track
approved drugs for adverse events through a postmarketing surveillance program.
Bumps in the Road
If the FDA decides that the benefits of a drug outweigh the known risks, the drug will receive
approval and can be marketed in the United States. But if there are problems with an NDA or if more
information is necessary to make that determination, the FDA may issue a complete response letter.
Common problems include unexpected safety issues that crop up or failure to demonstrate a drug’s
effectiveness. A sponsor may need to conduct additional studies–perhaps studies of more people,
different types of people, or for a longer period of time.
Manufacturing issues are also among the reasons that approval may be delayed or denied. Drugs
must be manufactured in accordance with standards called good manufacturing practices, and the FDA
inspects manufacturing facilities before a drug can be approved. If a facility isn’t ready for inspection,
approval can be delayed. Any manufacturing deficiencies found need to be corrected before approval.
“Sometimes a company may make a certain amount of a drug for clinical trials. Then when they go
to scale up, they may lose a supplier or end up with quality control issues that result in a product of
different chemistry,” says Kweder. “Sponsors have to show us that the product that’s going to be
marketed is the same product that they tested.”
John Jenkins, M.D., director of CDER’s Office of New Drugs, says, “It’s often a combination of
problems that prevent approval.” Close communication with the FDA early on in a drug’s development
reduces the chance that an application will have to go through more than one cycle of review, he says.
“But it’s no guarantee.”
The FDA outlines the justification for its decision in a complete response letter to the drug sponsor
and CDER gives the sponsor a chance to meet with agency officials to discuss the deficiencies. At that
point, the sponsor can ask for a hearing, correct any deficiencies and submit new information, or withdraw
The Role of User Fees
Since PDUFA was passed in 1992, more than 1,000 drugs and biologics have come to the market,
including new medicines to treat cancer, AIDS, cardiovascular disease, and life-threatening infections.
PDUFA has allowed the Food and Drug Administration to bring access to new drugs as fast or faster than
anywhere in the world, while maintaining the same thorough review process.
Under PDUFA, drug companies agree to pay fees that boost FDA resources, and the FDA agrees to
time goals for its review of new drug applications. Along with supporting increased staff, drug user fees
help the FDA upgrade resources in information technology. The agency has moved toward an electronic
submission and review environment, now accepting more electronic applications and archiving review
The goals set by PDUFA apply to the review of original new human drug and biological applications,
resubmissions of original applications, and supplements to approved applications. The second phase of
PDUFA, known as PDUFA II, was reauthorized in 1997 and extended the user fee program through
September 2002. PDUFA III, which extended to Sept. 30, 2007, was reauthorized in June 2002.
PDUFA III allowed the FDA to spend some user fees to increase surveillance of the safety of
medicines during their first two years on the market, or three years for potentially dangerous medications.
It is during this initial period, when new medicines enter into wide use, that the agency is best able to
identify and counter adverse side effects that did not appear during the clinical trials.
On September 27, 2007, President Bush signed into law the Food and Drug Administration
Amendments Act of 2007 which includes the reauthorization and expansion of the Prescription Drug User
Fee Act. The reauthorization of PDUFA will significantly broaden and upgrade the agency’s drug safety
program, and facilitate more efficient development of safe and effective new medications for the American
In addition to setting time frames for review of applications, PDUFA sets goals to improve
communication and sets goals for specific kinds of meetings between the FDA and drug sponsors. It also
outlines how fast the FDA must respond to requests from sponsors. Throughout a drug’s development,
the FDA advises sponsors on how to study certain classes of drugs, how to submit data, what kind of
data are needed, and how clinical trials should be designed.
The Quality of Clinical Data
The Food and Drug Administration relies on data that sponsors submit to decide whether a drug
should be approved. To protect the rights and welfare of people in clinical trials, and to verify the quality
and integrity of data submitted, the FDA’s Division of Scientific Investigations (DSI) conducts inspections
of clinical investigators’ study sites. DSI also reviews the records of institutional review boards to be sure
they are fulfilling their role in patient protection.
“FDA investigators compare information that clinical investigators provided to sponsors on case
report forms with information in source documents such as medical records and lab results,” says Carolyn
Hommel, a consumer safety officer in DSI.
DSI seeks to determine such things as whether the study was conducted according to the
investigational plan, whether all adverse events were recorded, and whether the subjects met the
inclusion/exclusion criteria outlined in the study protocol.
At the conclusion of each inspection, FDA investigators prepare a report summarizing any
deficiencies. In cases where they observe numerous or serious deviations, such as falsification of data,
DSI classifies the inspection as “official action indicated” and sends a warning letter or Notice of Initiation
of Disqualification Proceedings and Opportunity to Explain (NIDPOE) to the clinical investigator,
specifying the deviations that were found.
The NIDPOE begins an administrative process to determine whether the clinical investigator should
remain eligible to receive investigational products and conduct clinical studies.
CDER conducts about 300-400 clinical investigator inspections annually. About 3 percent are
classified in this “official action indicated” category.
The FDA has established an independent Drug Safety Oversight Board (DSOB) to oversee the
management of drug safety issues. The Board meets monthly and has representatives from three FDA
Centers and five other federal government agencies. The board’s responsibilities include conducting
timely and comprehensive evaluations of emerging drug safety issues, and ensuring that experts–both
inside and outside of the FDA–give their perspectives to the agency. The first meeting of the DSOB was
held in June 2005.
Once the review is complete, the NDA might be approved or rejected. If the drug is not approved,
the applicant is given the reasons why and what information could be provided to make the application
acceptable. Sometimes the FDA makes a tentative approval recommendation, requesting that a minor
deficiency or labeling issue be corrected before final approval. Once a drug is approved, it can be
Some approvals contain conditions that must be met after initial marketing, such as conducting
additional clinical studies. For example, the FDA might request a postmarketing, or phase 4, study to
examine the risks and benefits of the new drug in a different population or to conduct special monitoring
in a high-risk population. Alternatively, a phase 4 study might be initiated by the sponsor to assess such
issues as the longer term effects of drug exposure, to optimize the dose for marketing, to evaluate the
effects in pediatric patients, or to examine the effectiveness of the drug for additional
indications. Postmarketing surveillance is important, because even the most well-designed phase 3
studies might not uncover every problem that could become apparent once a product is widely used.
Furthermore, the new product might be more widely used by groups that might not have been well
studied in the clinical trials, such as elderly patients. A crucial element in this process is that physicians
report any untoward complications. The FDA has set up a medical reporting program called Medwatch to
track serious adverse events (1-800-FDA-1088). The manufacturer must report adverse drug reactions at
quarterly intervals for the first 3 years after approval, including a special report for any serious and
unexpected adverse reactions.
Recent Developments in Drug Approval
The Food and Drug Administration Modernization Act of 1997 (FDAMA) extended the use of user
fees and focused on streamlining the drug approval process. In 1999, the 35 drugs approved by the FDA
were reviewed in an average of 12.6 months, slightly more than the 12-month goal set by PDUFA. This
act also increased patient access to experimental drugs and facilitated an accelerated review of important
new medications. The law ended the ban on disseminating information to providers about non-FDAapproved uses of medications. A manufacturer can now provide peer-reviewed journal articles about an
off-label indication of a product if the company commits to filing a supplemental application to establish
the use of the unapproved indication. As part of this process, the company must still conduct its own
phase 4 study. As a condition for an accelerated approval, the FDA can require the sponsor to carry out
postmarketing studies to confirm a clinical benefit and product safety. Critics contend the 1997 act
compromises public safety by lowering the standard of approval. Within a year after the law was passed,
several drugs were removed from the market. Among these medications were mibefradil for hypertension,
dexfenfluramine for morbid obesity, the antihistamine terfenadine, and bromfenac sodium for pain. More
recently, additional drugs including troglitazone were removed from the market. Although the increase in
recalls might reflect the dramatic increase in drugs approved and launched, others argue that several
safety questions were ignored. Another concern was that many withdrawn drugs were me-too drugs
which did not represent a noteworthy advance in therapy. Persons critical of the FDA believe changes in
the approval process, such as allowing some new drugs to be approved based on only a single clinical
trial, expanded use of accelerated approvals, and the use of surrogate end points, have created a
dangerous situation. Proponents of the changes in the approval process argue that there is no evidence
of increased risk from the legislative changes, and that these changes improve access to cancer patients
and those with debilitating disease who were previously denied critical and lifesaving medications.
New drugs are an important part of modern medicine. Just a few decades ago, a disease such as
peptic ulcers was a frequent indication for major surgery. The advent of new pharmacologic treatments
has dramatically reduced the serious complications of peptic ulcer disease. Likewise, thanks to many new
antiviral medications, the outlook for HIV-infected patients has improved dramatically. It is important that
physicians understand the process of approving these new medications. Understanding the process can
promote innovation, help physicians assess new products, underline the importance of reporting adverse
drug events, and provide physicians with the information to educate patients about participating in a
THANKS AND REGARD'S
DR ANTHONY MELVIN CRASTO Ph.D
GLENMARK SCIENTIST , INDIA
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