Different stages of the drug development and approval process in the USA, lead from preclinical trials (testing in animals), first application in humans through limited and broad clinical tests, to postmarketing studies.

	Years	Test Population	Purpose	Success Rate
Preclinical Testing	3.5	Laboratory and animal studies	Assess safety and biological activity	5,000 compounds evaluated
File IND at FDA
Phase I	1	20 to 80 healthy volunteers	Determine safety and dosage	5 enter trials
Phase II	2	100 to 300 patient volunteers	Evaluate effectiveness, look for side effects
Phase III	3	1000 to 3000 patient volunteers	Verify effectiveness, monitor adverse reactions from long-term use
File NDA at FDA
FDA	2.5	Review process / Approval		1 approved
	12 Total
Phase IV	Additional Post marketing testing required by FDA

By Dale E. Wierenga, Ph.D. and C. Robert Eaton
Office of Research and Development
Pharmaceutical Manufacturers Association

'In reviewing this report, it is important to keep in mind the realities of the drug discovery and development process. The U.S. system of new drug approvals is perhaps the most rigorous in the world. On average, it costs a company $359 million to get one new medicine from the laboratory to the pharmacist's shelf, according to a February 1993 report by the Congressional Office of Technology Assessment.'

See also Phase 1 2 3 4 Drug Trials, Clinical Trial, Food and Drug Administration, and European Medicines Agency.

The alpha decay is a corpuscular radiation. Two protons and two neutrons (a helium core) are emitted from the atomic nucleus. Because of the high biological effectiveness, the use of alpha particle radiation is not allowed in diagnostic nuclear medicine.

This term usually refers to the storage of patient data and images. Images are best archived in digital form (e.g., on optical disks, DVDs, PACS systems) and not only on films (hard copies, prints). Data compression via a reduction in matrix size, pixel depth or CT numbers, will result in a loss of spatial and contrast resolution. Digital images should be converted into a universal format such as DICOM. Raw data saving is necessary when additional image reconstructions are required.

See also Picture Archiving and Communication System, and Digital Imaging and Communications in Medicine.

(Bq) Becquerel is the system international (SI) since 1985 new unit of radioactivity. 1 becquerel is equal to 1 disintegration per second.
1 Bq = 0.027 x10^-9 Ci (Curie).
In medicine and radiation protection the SI measurement units of becquerel, gray and sievert (should) have replaced the conventional units of curie, rad and rem.

To convert:


See also Gray, Sievert, Roentgen Equivalent In Man, Radiation Absorbed Dose, Count and Becquerel Antoine Henri.

The company is developing and making specialized medicines for treating multiple sclerosis, dermatological disorders, female health concerns, cancer and is creating new diagnostic imaging techniques. Berlex, Inc. is a pioneer in the imaging market. It has introduced a broad range of imaging agents. Its contribution began in 1988 with the introduction of the world's first magnetic resonance imaging agent, Magnevist® (gadopentetate dimeglumine) injection. Berlex is headquartered in New Jersey and the U.S. affiliate of Bayer Schering Pharma AG, Germany.