**1. Introduction**

Radiopharmaceuticals were first defined by the Federal Register of the USA as radioactive agents- potassium (40K) and carbon (14C) based natural compounds- or biological products contain unstable nuclei which may degrade spontaneously and emit photons or nuclear particles. These drugs might be prepared using nuclide generator or nonradioactive reagent [1].

Radiopharmaceuticals are categorized into 4 main classes: research, diagnostic, environmental and therapeutic pharmaceuticals as presented in **Figure 1**. Research radiopharmaceuticals are administrated to track metabolic reactions and kinetics including bio-distribution, bioavailability, pharmacokinetic, and pharmakodynamic of a drug that is intended to be used later as nonradioactive form [1].

#### *Radiopharmaceuticals - Current Research for Better Diagnosis and Therapy*

#### **Figure 1.**

*Radiopharmaceutical applications in diagnosis, therapeutic, monitoring environment, and new trends in research.*

Diagnostic radiopharmaceuticals Known as radioactive drugs/ompoundsc which used tracers for many diseases. Using gamma-ray emissions from radiopharmaceuticals drugs would help on broadcasting their positions inside the body. The concentrations of the radioactive materials could be deduced by observing these broadcasts in several organs. Images of different organs with low-resolution could be obtained using the signals [2].

The pharmacodynamics -the metabolism of the drug inside the body- and the kinetics could be studies by monitoring these broadcasts in a time-dependent manner. The device of monitoring is a collimated external gamma-ray detector. Therefore, in diagnosis purposes the radioactive materials are used to detect any sort of molecular, biochemical, physiological, and even anatomical abnormalities.

However, the diagnostic radioactive materials are not limited to gamma emitters types which allow their *in-situ* determination with noninvasive external radiation detectors. There are other types of radiopharmaceuticals that made of tritium, phosphorus 32, or carbon 14. Remarkably, these isotopes do not emit the same type of rays- gamma rays- therefore, it is impractical to monitor and examine their situation inside the body by external detectors. However, this type of isotypes could be applied in tracer diagnosis by analysis of samples. For instance, the administration of 14C to glucose and monitoring the elimination of CO2 (14C) in the breathing as metabolic end-product and used as indication for the assimilation of the compound, its metabolism throughout the body.

There are many variant body samples and fluids could be considered as well such as urine, blood, and biopsies samples in specific conditions.

Therapeutic radiopharmaceuticals are radioactive substance which could help in delivering the radiation entirely of body tissues by administration to radioactive substances such as iodide I3I for thyroid removal in hyperthyroidism patients. The thyroid organ is irradiated entirely by radioactive iodine. Other different radiopharmaceutical materials could be used in treatment of cancer and known as radiotherapy [1].

*Radiopharmaceuticals: On-Going Research for Better Diagnosis, Therapy, Environmental… DOI: http://dx.doi.org/10.5772/intechopen.99204*

### **2. History of Radiopharmacy**

Although training on the use and management of labeled compounds is provided in various institutions, the demand for pharmacists who specialize in radiolabeled drugs has been determined, and radiopharmaceuticals have become the first specialty in the late 1960 in Pharmacy school at the U. of Southern California (USC), USA. The short-term research courses (usually 30 days for non-graduate students) and the radiopharmaceutical technician training program conducted from 1969 to 1986 enabled 201 pharmacists and other personnel to obtain a master's degree in radiopharmaceuticals, and 15 of them obtained technology Certificate, and more than 500 people have participated and provide such expert training elsewhere and completed its plan in 1986 [3].

Clinical needs can be in image performances which may have a vital role either in staging or prognosis of the disease. Long ago, several programs that are educational and anxious with radiopharmaceutical analysis have not addressed this question. The program is frequently specialize in labeling a particular compound and on its application without any thoughts for its potential application in future. Even once a specific biological target is being targeted, the question of whether or not it addresses a true clinical would like is usually not considered [4]. The usage of radiolabeled organism antibodies for imaging a neoplasm is taken into account a decent example. On the last decades, a great deal of studies were on developing programs based on aforesaid materials and this terminated and resulted in radiopharmaceuticals that may image cancer effectively and thought of as highly sensitive and specific methodology for imaging comparable or superior to other techniques.

#### **3. Obstacles in academic research in radiopharmaceutical field**

Most important modifications in health care in west were in the 1990's. At this time, many resources became unrestricted in conjunction with complete clinical freedom and open-ended budgets this led to high level of control for health-care requirements with limited budgets, established protocols, and internal markets. The development of drug has regulated as well. Radiopharmaceuticals considered as one of the regulators which regulate conventional drugs which in turn increase the costs for the development of these drugs.

The academic discoveries in commercial development of radiopharmaceuticals were limited due to limitation in radiopharmaceutical industry and many vicissitudes in the institutions carrying out development in this field.

National nuclear centers whole over the world faced a lot of obstacles such as being privatized or being overburdened to make commercial gains. Academic funding for scientific research has also been cut off for long periods at universities. The academic curiosity was one of many reasons for scientists to put radiopharmaceutical field in the scope of research. To gain success in this field, projects should be developed, more directed, productive, and focused than was required earlier. Particularly, developing the clinical application of the product must be taken in consideration combined with the overcoming the financial obstacles. Therefore, unique new radiopharmaceuticals must fulfill a clinical requirement [5].

#### **4. Nuclear medicine: clinical uses**

Many new therapies in clinical practice have other requirements, such as managed care plans and expensive restrictions. This represents both an opportunity

and a challenge for new radiopharmaceuticals [6]. It is necessary to maintain a reputation for safety and efficacy, and to improve existing treatments for any new products. In such a restrictive environment, it will be difficult to find a place in the market for radioactive compounds of these new drugs in clinical practice. Another way to introduce new and expensive treatments is to determine the subset of patients most likely to benefit from that particular treatment. The unique advantage of medicine is that it has the ability to combine diagnostic and therapeutic radionuclides for the same purpose, and may remain unchanged. In the future, diagnostic and therapeutic radiopharmaceutical pairs will increasingly be used to perform this function [6]. At the scientific level, radiopharmaceutical research has undergone a process of substitution in recent years. This review of compounds which describes certain aspects of current radiopharmaceutical research that have appeared in recently published literature or have become the subject of conference presentations [7]. Some of these issues are also the subject of more detailed review. However, this chapter deliberately excludes certain subject areas, especially not trying to cover developments in the field of positron emission tomography [7].

Radiopharmaceuticals are the cornerstone of nuclear medicine. Although there are many types of drugs that can study the structure and function of many essential organs, there is still a need for radiopharmaceutical substitution to study the subtle mechanisms of human body function. Under this trend, I5O, I8F and 123I appeared in the throttle body. With the emergence of such radionuclide-labeled drugs, especially the most widely used 99mTc, people are also doing their best to translate this success into daily clinical practice. β-labeled drugs can also be used for targeted radiotherapy of various malignant tumors. In addition to laboratories in industrialized countries, some developing countries have also shown interest in these fields and participated in research projects [8].

Therapeutic radiopharmaceuticals have a critical effect on patient care specifically on medicine which have a promising role in the future. Many of latest therapies in clinical practice in need of different requirements like managed care programs, restrictions which are expensive. This symbolizes both a chance and a challenge for brand spanking new radiopharmaceuticals [6]. Efficacy and safety are among many others advantages to be added over the current treatments for any new product. Therefore, in such a restrictive environment there'll be an issue for these new medicinal radio compounds to urge their place within the routine of clinical practice. Though, another route to abide with the new protocols is to define which group of patients may benefit from this special treatment. The strength of nuclear medicine is its capability to merge the uses of radionuclides in both diagnostic and therapeutic purposes for matching targets in diagnostic and therapeutic radiopharmaceuticals [6].

This chapter describes, generally terms, some aspects of current radiopharmaceutical research which have appeared within the recent published literature or are the topic of conference presentations [7]. Several of these topics are also the subject of more detailed reviews during this publication. However, some specialized areas of labor are deliberately excluded from this chapter, especially, no attempt is formed to hide developments within the field of Positron Emitting Tomography [7].

#### **5. Radiopharmaceuticals and its bodily functions**

Radiopharmaceuticals form the cornerstone of nuclear medicine. While the existing range of radiopharmaceuticals permits study of the structure and function of many important organs, there is a need for new radiopharmaceuticals that could

*Radiopharmaceuticals: On-Going Research for Better Diagnosis, Therapy, Environmental… DOI: http://dx.doi.org/10.5772/intechopen.99204*

be used to explore more subtle mechanisms of bodily functions. Important progress has been achieved in this direction by the development of tracers labeled with cyclotron produced isotopes, including UC, 13 N, I5O, I8F and 123*I. major* efforts are also under way to translate this success into regular clinical practice by developing similar agents labeled with metallic radionuclides, particularly with the most widely used 99mTc. The agents labeled with beta emitting isotopes for potential use in the targeted radiotherapy of various malignancies is also being widely pursued. In addition to laboratories in advanced countries, several developing countries are also interested in these areas and have been participating in research programs organized by the IAEA. New advancement of Radiopharmaceuticals for therapy and Diagnosis will help speeding communication, and widespread knowledge for the better health of human being [8].
