Applications of Radiopharmaceuticals.pptx

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1. Applications of Radiopharmaceuticals By Ghawas khan Mphil 1 st semester Quad e Azam University Islamabad Pakistan

2. Applications of Radiopharmaceuticals The application of radiopharmaceuticals are divided into two major areas, D iagnostic uses Therapeutic uses To over come the quick release of radiopharmaceuticals its conjugated covalently with large size molecules. Because if the excretion too rapidly: then the drug wont concentrate in the target site and therapeutic values will not be achieved. To avoid trapping and degradation of the agents by the RES, therapeutic entities must be designed not to be recognized by the RES. Pre-therapeutic administration of nonradioactive antibodies (preload) can be used to saturate the RES and modify the distribution of the radiolabeled antibody.

3. Applications of Radiopharmaceuticals Myocardial Perfusion Test: Pictures of the resting heart are taken Pictures of the stressed heart are taken Myocardial perfusion treadmill stress test Myocardial perfusion medicine based test Myocardial perfusion imaging is performed most commonly using  Tc-99m ( sestamibi ) or Tc-99m ( tetrofosmin ). Diseased-to-normal tissue contrast is determined by the tracer retention fraction, which decreases nonlinearly with flow . Reduced tissue perfusion results in reduced tracer retention.

4. Applications of radiopharmaceuticals Thyroid function test: I-131 is given in capsule or solution farm. It is absorbed into the blood stream and then taken by the tyroid gland. The extent of uptake of the dose by the gland helps assess thyroid function. Imaging of the gland can also obtained to see how much I is taken by the gland.

5. Applications of radiopharmaceuticals Kidney function test ( Renography ): Sodium iodide (I-131) is eliminated predominantly through renal clearance. When I-131 was labeled with orthoiodohippuric acid ( 131 I - orthoiodohippurate , or OIH) and intravenously injected. kidney tubules would actively secrete this agent into urine. Measuring the time course of activity over the kidney with a gamma camera and plotting the rate of radioactivity accumulation and removal versus time yields a measure of kidney function. This dynamic study, termed a renogram , is particularly useful to assess renal function in patients with transplanted kidneys. Post-transplantation renography can be used for the diagnosis of vascular and urological complications .

6. Applications of radiopharmaceuticals Kidney function test ( Renography ):

7. Applications of radiopharmaceuticals Vent-Perfusion lung imaging: Radiopharmaceuticals are useful to evaluate a patient’s response to drug therapy and surgery . These agents can detect early changes in physiologic function that come before morphologic or biochemical end points . The patient inhale an aerosol containing the radioactive compound i.e 99mTc macroaggregated albumin particles . A gamma cam detects the gas as it flows through the lungs and allows the clinician to asses how well the air is flowing or ventilating. Once the embolism is confirmed and thrombolytic and/or anticoagulant therapy initiated, this lung- perfusing agent can be administered again to evaluate its resolution with drug therapy.

8. Applications of radiopharmaceuticals Octerioscan : O ctreotide , a synthetic analogue of somatostatin, with the In-111 labeled analogue pentetreotide. OctreoScan , became the first radiolabeled peptide approved by the FDA . This agent has made possible the detection of small (0.5 to 1.0 cm) primary and metastatic tumors, including those of several brain tumor types, pancreatic islet tumors, neuroblastomas , carcinoids, thymomas , and melanomas, among others. A further refinement of Octerioscan is gallium scans which superimpose the scans on a CT scan.

9. Applications of radiopharmaceuticals Therapeutic use of Radiopharmaceuticals : Therapeutic radiopharmaceuticals are radiolabeled molecules designed to deliver therapeutic doses of ionizing radiation to specific disease sites, such as cancerous tumors, with high specificity in the body. Difficulties in the design and development of a highly selective radiolabeled drug carrier include D rug delivery. M aximizing the residence time of radioactivity at target sites. I n vivo catabolism and metabolism of the drug . O ptimization of relative rates of the radiolabeled drug or metabolite clearance from non-target sites.

10. Applications of radiopharmaceuticals Thyroid disease has been treated with sodium iodide, I-131 T hyroid gland absorbs nearly all of the iodine in the body. R adioactive iodine (RAI, also called I-131) can be used to treat thyroid cancer. The RAI collects mainly in thyroid cells, where the radiation can destroy the thyroid gland and any other thyroid cells (including cancer cells) that take up iodine, with little effect on the rest of your body. The radiation dose used here is much stronger than the one used in radioiodine scans. The effect of this treatment on the thyroid gland usually takes between one and three months to develop. Maximum benefit occurs three to six months after treatment. Usually, a single dose is successful in treating hyperthyroidism. However, rarely, a second treatment is necessary. A third treatment is very rarely necessary.

11. Applications of radiopharmaceuticals Polycythemia vera can be treated with sodium phosphate, P-32 Radioactive phosphorus is give via IV route and its absorbed by the spongy bones which are involved in the production of red blood cells, the radio activity of this element suppresses the excessive production of RBCs. The radio isotope is radially distributed to all tissues and is concentrated in those tissues where the proliferation is most rapid. There is a small risk that the patient might not produce enough red blood cells and platelets. So it might be needing blood tests after treatment to check for this. What is polycythemia vera ? Polycythemia vera is a rare blood disorder in which there is an increase in all blood cells, particularly red blood cells. The increase in blood cells makes your blood thicker. This can lead to strokes or tissue and organ damage.

12. Applications of radiopharmaceuticals Peritoneal effusions ( ascities ) can be treated with chromic phosphate, P-32 CP As a palliative treatment for malignant ascites, P-32 CP was instilled intraabdominally eight times. Adverse effects were limited to the third instillation, when abdominal pain occurred as a result of leakage of the P-32 CP in the subcutaneous tissue. The P-32 CP instillations reduced the frequency of paracentesis for almost 1 year, until disease progression prevented palliation .

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