The Drug Development and Approval Process
15.4.1 The Drug Development and Approval Process
This brief summary of the drug development process is provided to help define the origins of different names used to identify drugs.
Drugs intended for clinical use undergo several phases of development before they can be considered for human use. Animal studies are performed initially to assess pharmacologic and toxicologic effects. While clinical studies are being conducted, animal studies may continue to assess effects on reproduction, teratogenicity, and carcinogenicity.4(p63)
To perform clinical studies in the United States, the developer or manufacturer must obtain an investigational new drug (IND) approval from the US Food and Drug Administration (FDA).4(p59) Once an IND application has been filed, the company must apply to USAN for a nonproprietary name. Until a nonproprietary name has been approved, the developers of a drug may refer to it by the code name. The code designation is usually alphanumeric, with letters to refer to the institution or manufacturer that assigns the code designation for the drug and numbers to refer to the chemical compound.1(pp13-14)
Drug developers must adhere to the Declaration of Helsinki and obtain institutional review board approval and patient informed consent to perform drug studies in humans. Phase 1 studies generally are conducted in healthy volunteers to assess safety, biological effects, metabolism, kinetics, and drug interactions.4(p60) Phase 2 studies usually are conducted to establish the therapeutic efficacy of a drug for its proposed indication and to study dose range, kinetics, and metabolism.4(p60) Phase 3 trials typically are randomized controlled trials that assess a drug’s safety and efficacy in a large sample of patients (generally 2000 to 3000).4(p61) The patients selected have the condition(s) for which the drug is thought to be effective and for which the manufacturer wishes to obtain approval. The 3 phases of clinical testing take from 2 to 10 years (average, 5.6 years).4(p60) The FDA reviews drugs for approval in less than 1 year and performs expedited reviews for drugs for life-threatening illnesses.4(p59)
In the United States, a drug cannot be marketed or prescribed (other than for specific exceptions) until it has been approved by the FDA. The FDA approves labeling for the drug for specific indications for which the FDA believes sufficient evidence of effectiveness has been provided. Approved labeling defines the indications for which the drug can be marketed. The FDA does not approve indications for which a drug may be prescribed, since a company may not study all possible conditions for which a drug may be effective. In what is known as off-label prescribing, physicians may prescribe a marketed drug for indications for which it does not have FDA approval for labeling or marketing. The approved labeling is included in drug packaging, marketing materials, and the Physicians’ Desk Reference.5
Because the number of patients tested before a drug is approved is insufficient to identify rare adverse events, some countries require physicians to report adverse events experienced by their patients, and some manufacturers may be required to systematically monitor drug adverse events after approval in a process known as postmarketing surveillance. Physicians and other health care professionals in the United States should report adverse drug events to the voluntary reporting system MedWatch (http://www.fda.gov/medwatch) or to the pharmaceutical manufacturer, which is obligated to file reports with the FDA. The United Kingdom, Canada, New Zealand, Denmark, and Sweden have legally mandated adverse event reporting systems.4(p62) In addition, the WHO maintains the WHO Collaborating Centre for International Drug Monitoring in Uppsala, Sweden.6