**8.3 Computational chemistry of metal-based radiopharmaceuticals**

Calculation of radiopharmaceutical doses is a very crucial process and considered one of the main task of radiopharmacist as illustrated later. It is noteworthy to mention that there is the method of prescription calculation is completely different from conventional organic drugs. The most common method of calculation or computational chemistry of metal-based radiopharmaceuticals [14]. Other factors must be considered and may have role in pharmacokinetic and biodistribution, e.g. molecule geometry, dipole moments, ionic charge [15].

#### **8.4 Bioevaluation (biological assessment)**

Eventhough methods of diagnosis and therapy are very important for both patients and physicians but bioevaluation or biological assessment protocol(s) are highly recommended [16–20]. The studies proved that some chelating agents (e.g. EDTA and DPTA) may chelate radionuclides to provide good images especially in cases of advanced cancer. For early diagnosis, Re-186(V) and Re-188(V)-DMSA are among drugs which will help in both diagnosis and monitoring cancer with good bio-distribution and pharmacokinetics properties [21]. This will enable specialist to understand if the radiopharmaceutical reached the appropriate location or site(s) (tumor for example). This also may enhance the delivery and improver the efficacy of drug [21]. Interestingly, measuring all three tumor space could be examined in vivo using drugs labeled with 95 mPt [22]. This protocol is valuable for cytotoxic drugs *via* the first pass phenomenon, e.g. cisplatin and 5-FU. However, other drugs

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

that control tumor *via* a slow diffusion mechanism will behave differently. The use of radiopharmaceutical in meager quantity may help in calculating the number of locations/sites needed to attain the optimal delivery and bio-distribution to reach the best therapeutic activity [23–27].

Coupled with the ease of antibody production, these facts make 125 I-labeled immunoassays an ideal choice for many research activities [28, 29], especially in the medical field where radioisotopes are In short, even a cursory examination of the public health statistics of different countries on all continents shows the need for a simple, economic, and reliable analytical with this in mind, it is expected that [30].

#### **8.5 Current status of radioactive signal immunoassays**

The future development of radiolabeled immunoassays use reagents containing radioisotopes as indicators to monitor the distribution of free and bound antigens or free antibodies The distribution of free antibodies (free Immune radiological reagent analysis. (IRMA) [28, 29, 31–33].

#### **8.6 Development of a simple immunofluorescence test method that uses AVIDIN to connect with general polystyrene spheres**

Immunoradioassay (IRA) based on using beads of polystyrene as solid phase conjugated to avidin [34]. The commercially MoAbs is bio-tinylated with N-hydroxysuccinimide ester of biotin aminocaproate, and the detection Ab is I125.

A simple assay composed mainly of two steps;, mixing 2 labeled Abs with either sample or positive control [35]. This method has been used for hormonal analysis; Lutinizing hormones (LH), Follicle Stimulating Hormones (FSH), and prolactin [36]. For example, theaccuracy in analysis of prolactin is 8 (μU/ml (0.3 ng/ml), FSH is 1 mlU/ml, and LH is 0.9 mlU/ml [37].

#### **8.7 Magnetic particle separation technique**

There are 5 classes of magnetic particles(MP) (with/or without –CHO, NH2-, and COOh groups) were used to conjugate the 1st or 2nd antibody(Ab) using three methods; immmunoaffinity, adsorption, and chemical coupling to form 4 different MPAbs [38]. The 2nd immobilized Ab on polyacrolein MPs through -CHO and also the 1st Abs immobilized on -COO polystyrene MPs through -COOH to use in RIAs and/or IRMAs [39]. Commercial MPS were immobilized on NH2- for "Streptavidin" to separating polymerase chain reaction product quantitatively for CMV (Cytomegalovirus) [40, 41].

There are over forty eight cyclotrons and forty two reactors to provide radioisotopesfor biomedical applications [42, 43].

Nuclear reactors have played a main role in production of radioisotopes required for medical, industrial, agricultural purposes, education within the nuclear sciences and research. Millions of people worldwide have benefited from the 99Mo - > 99mTc generator for diagnostic imaging, and 131I for the treatment of cancer. Advances in accelerator and medical imaging technology are driving the demand for radioisotopes and radiopharmaceuticals required by nuclear medicine [44]. Conditions like public perception arising from concern for the environment either from radiation accidents or future storage of nuclear waste, additionally because the operating and replacement costs for aging reactors are factors influencing the prospects of future availability of radioisotopes. This may well be often reflected in recent decisions taken to initiate the de-commissioning of some research TRIGA reactor(s) that were installed in hospitals during the 1960's [45].
