PRODUCTION AND QUALITY CONTROL OF RADIOPHARMACEUTICALS

Transcription

1 PRODUCTION AND QUALITY CONTROL OF RADIOPHARMACEUTICALS RAYMOND TAILLEFER, M.D. FRCP(c), ABNM DIRECTOR, DEPARTMENT OF NUCLEAR MEDICINE HOPITAL DU HAUT-RICHELIEU,CANADA Disclosures to Report: Grant Research Support: Lantheus Medical Imaging Consultant: Lantheus Medical Imaging

2 OVERVIEW 1- PRODUCTION OF RADIONUCLIDES 2- RADIOISOTOPE GENERATORS 3- PREPARATION OF RADIOPHARMACEUTICALS 4- QUALITY CONTROL 5- Tc-99m «COLD KIT»

3 PRODUCTION OF RADIOISOTOPES NUCLEAR REACTOR CYCLOTRON GENERATOR Primary sources Secondary source

4 Nuclear bombardment Hit nucleus of stable atom with sub-nuclear particles: neutrons, protons, alpha particles etc. There are two main methods of performing this bombardment 1. Inserting target in a nuclear reactor - fine for longer-lived isotopes 2. Using a charged-particle accelerator called a 'cyclotron' electron neutron proton

5 Radioisotopes in Nuclear Medicine REACTOR Molybdenum-99 (f) Technetium-99m Iodine-131 Phosphorus-32 Yttrium-90 Samarium-153 Strontium-89 (f) Iodine-125 Cr-51 C-14 Xe-133 (f) Sr-90 (f) -> Y-90 Linear Accelerator or High Energy Cyclotron Thallium-201 Indium-111 Iodine-123 Gallium-67 Sr-82 -> Rubidium-82 Co-57 Low Energy Cyclotron Fluorine-18 Carbon-11 Nitrogen-13 Oxygen-15 20

6 Production-Short Hand Equation 68 Zn (p, 2n) 67 Ga Target Bombarding particle Emitted particle(s) Product

7 Reactor Produced Radioisotopes Nuclear Fission U + 0n 92 U 42 Mo + 50Sn n Heavy nuclei ( 235 U) Absorption of a thermal neutron (E ~ ev) Break up (fission) into two nuclei of similar atomic weight Neutrons are produced which can be absorbed by other heavy nuclei Neutron/Proton ratio is high Process continues until all the nuclear fuel is spent Products different atomic number High specific activity

8 Neutron Capture vs. Fission 98 Mo 42 (n, ) 99 Mo U 92 (n,f) 99 Mo 42 Cost less to prepare Low specific activity 75mCi/mg Low concentration Costs more to prepare High specific activity 500Ci/mg Smaller column Less shielding Higher concentration

9 Reactors producing radionuclides used in medicine Belgium France Netherlands South Africa Canada Australia

10 Processes of 99 Mo/ 99m Tc generator n Mo-99 + Impurities Reactor sites responsible for producing radionuclide Processing plant responsible for sterile, pyrogen free product Carrier Free; High specific activity <0.05uCi I131 & Ru103; <0.0006uCi Sr89; <0.1uCi others / mci Tc99m

11 PREPARATION OF RADIOPHARMACEUTICALS: RADIONUCLIDE USED AS A TRACER IN MEDICINE, PRESENTED IN A SPECIFIC CHEMICAL FORM WHICH CONTROLS ITS BIOLOGICAL FATE WHEN ADMINISTERED TO THE PATIENT. 1- EXTRACTION OF THE RADIONUCLIDE FROM THE BULK OF THE TARGET SUBSTANCE

12 PREPARATION OF RADIOPHARMACEUTICALS: RADIONUCLIDE USED AS A TRACER IN MEDICINE, PRESENTED IN A SPECIFIC CHEMICAL FORM WHICH CONTROLS ITS BIOLOGICAL FATE WHEN ADMINISTERED TO THE PATIENT. 1- EXTRACTION OF THE RADIONUCLIDE FROM THE BULK OF THE TARGET SUBSTANCE 2- PURIFICATION TO REMOVE UNWANTED CHEMICAL AND RADIONUCLIDE IMPURITIES

13 PREPARATION OF RADIOPHARMACEUTICALS: RADIONUCLIDE USED AS A TRACER IN MEDICINE, PRESENTED IN A SPECIFIC CHEMICAL FORM WHICH CONTROLS ITS BIOLOGICAL FATE WHEN ADMINISTERED TO THE PATIENT. 1- EXTRACTION OF THE RADIONUCLIDE FROM THE BULK OF THE TARGET SUBSTANCE 2- PURIFICATION TO REMOVE UNWANTED CHEMICAL AND RADIONUCLIDE IMPURITIES 3- CHEMICAL CONVERSION OF THE PURE RADIONUCLIDE INTO A BIOLOGICALLY SPECIFIC FORM

14 PREPARATION OF RADIOPHARMACEUTICALS: RADIONUCLIDE USED AS A TRACER IN MEDICINE, PRESENTED IN A SPECIFIC CHEMICAL FORM WHICH CONTROLS ITS BIOLOGICAL FATE WHEN ADMINISTERED TO THE PATIENT. 1- EXTRACTION OF THE RADIONUCLIDE FROM THE BULK OF THE TARGET SUBSTANCE 2- PURIFICATION TO REMOVE UNWANTED CHEMICAL AND RADIONUCLIDE IMPURITIES 3- CHEMICAL CONVERSION OF THE PURE RADIONUCLIDE INTO A BIOLOGICALLY SPECIFIC FORM 4- ADDITION OF THE NECESSARY EXCIPIENT TO MAKE THE PREPARATION SUITABLE FOR ADMINISTRATION TO THE PATIENT

15 PREPARATION OF RADIOPHARMACEUTICALS: RADIONUCLIDE USED AS A TRACER IN MEDICINE, PRESENTED IN A SPECIFIC CHEMICAL FORM WHICH CONTROLS ITS BIOLOGICAL FATE WHEN ADMINISTERED TO THE PATIENT. 1- EXTRACTION OF THE RADIONUCLIDE FROM THE BULK OF THE TARGET SUBSTANCE 2- PURIFICATION TO REMOVE UNWANTED CHEMICAL AND RADIONUCLIDE IMPURITIES 3- CHEMICAL CONVERSION OF THE PURE RADIONUCLIDE INTO A BIOLOGICALLY SPECIFIC FORM 4- ADDITION OF THE NECESSARY EXCIPIENT TO MAKE THE PREPARATION SUITABLE FOR ADMINISTRATION TO THE PATIENT 5- TESTING THE QUALITY OF THE FINAL PRODUCT

16 99Mo - 99mTc- GENERATOR APPLICATION OF SHORT-LIVED RADIONUCLIDE RESTRICTED TO A PLACE CLOSE TO ITS SOURCE. THE SHORTER THE T½, THE CLOSER TO THE SOURCE ARE THE PRACTICAL LIMITS PARENT ( LONG-LIVED RN) DECAYS TO FORM A DAUGHTER (SHORTER- LIVED RADIONUCLIDE) SUITABLE MEANS FOR SEPARATING THE TWO SPECIES. PARENT = TRANSPORTABLE SOURCE OF THE DAUGHTER RADIONUCLIDE

17 Concept of a Radioisotope Generator 99 Mo 99 Mo 99 Mo 99m Tc Parent isotope is bound to a matrix Parent isotope decays to its daughter 99m Tc Daughter is eluted from the column Requires suitably matched parent & daughter isotopes

18 MOST IMPORTANT GENERATOR SYSTEM USED FOR PROVISION OF 99mTc FROM FISSION PRODUCT 99Mo. U (n, fission) 99Mo 98Mo (n,gamma) 99Mo 100Mo (p, gamma) 99Mo DAILY ACCESS TO 99mTc (short T½ = 6 hours). ONCE-WEEKLY DELIVERY OF 99Mo (T½ = 66 hours). EXTRACTION OF 99mTc BY SIMPLE COLUMN CHROMATOGRAPHY.

19 99Mo - 99mTc- GENERATOR SYSTEM RADIOACTIVITIES OF BOTH 99Mo AND 99mTc ARE CONTINUALLY CHANGING. 99Mo LEVEL DECREASES BY RADIOACTIVE DECAY. 99mTc LEVEL : INFLUENCED BY BOTH GROWTH AND DECAY EFFECTS. LEVEL OF 99mTc: COMPLEX EXPONENTIAL FUNCTION OF TIME TRANSIENT-EQUILIBRIUM

20 DECAY-GROWTH OF 99Mo-99mTc Transient equilibrium

21 SEPARATION OF 99mTc FROM 99Mo BASED ON THE DIFFERENCES IN THE PHYSICAL OR CHEMICAL PROPERTIES OF 99Mo and 99mTc. COLUMN CHROMATOGRAPHY : 99Mo IS IMMOBILIZED ON AN ALUMINA COLUMN. PASSAGE OF A SALINE SOLUTION THROUGH THE COLUMN WILL REMOVE (ELUTE) THE 99mTc AS A SODIUM PERTECHNETATE SOLUTION. GEL GENERATOR : COLUMN OF AMORPHOUS ZIRCONIUM MOLYBDATE.

22 99 Mo/ 99m Tc Generator 99 Mo adsorbed onto alumina column having two ionic charges 99 Mo decays into 99m Tc 99m TcO 4- form (pertechnetate) has one ionic charge

23 Terminology Related to Alumina Column 99 Mo/ 99m Tc Generators Eluting or Milking Eluent Eluate Ion Exchange Column Fractional Elution Specific Concentration Elution Efficiency

24 Elution with NS removes the weakly bound 99m TcO 4 - leaving the 99 MoO 4 2- on the column The eluent is Na 99m TcO 4 (sodium pertechnetate)

25 Tc-99m Dry Column Generator

26 Quality Control of Mo99/Tc99m Generator Eluates By manufacturer: Sterility, pyrogens, and radionuclidic contaminants in Mo-99 By user after each elution: Mo-99 radionuclide impurity Alumina (Al +3 ) present in eluate Hydrolyzed Reduced Tc-99m ( 99m TcO 2 )

27 QUALITY CONTROL OF 99mTc-ELUATE 1-99Mo BREAKTHROUGH. 2- OTHER RADIONUCLIDE CONTAMINATION. 3- ALUMINUM BREAKTHROUGH. 4- ph.

28 OTHER RADIONUCLIDE CONTAMINATION GENERATOR USING FISSION-PRODUCED 99Mo. USP LIMITS : 131 I : 0.05 µci/mci ( 0.05 Bq / kbq). 103 Ru : Sr : Sr : other Beta and gamma emitting : <0.01% MULTICHANNEL PULSE HEIGHT ANALYZER. PERFORMED BY MANUFACTURER.

29 99Mo BREAKTHROUGH ORIGINATES FROM THE SMALL QUANTITY OF 99Mo THAT MAY BE ELUTED WITH 99mTc. USP : 0.15 µci 99Mo / mci of 99mTc ( 1.5Bq / 10 kbq). DETECTION OF 740 AND 780 Kev PHOTON OF 99Mo. DOSE CALIBRATOR COLORIMETRIC TEST: ADDITION OF PHENYLHYDRAZINE TO THE ELUATE: COLOR CHANGE.

30 Radionuclide Purity Test Moly Breakthrough Test 6mm Tc99m 140keV Mo99 740keV & 780keV Dose Calibrator 6mm lead Moly Canister Subtract background

31 ALUMINUM BREAKTHROUGH DERIVED FROM ALUMINA BED OF THE GENERATOR. INTERFERENCE WITH THE PREPARATION OF VARIOUS RADIONUCLIDES 99mTc-Sulfur colloid 99mTc- red blood cells USP LIMITS : <10 µg Al/ml. COLORIMETRIC METHOD. EXCESSIVE AMOUNT OF ALUMINUM = LACK OF STABILITY OF THE COLUMN. ph : normal : 4.5 to 7.5

32 Chemical impurity Paper coated with aurintricarboxylic acid Forms a pink precipitant with aluminum ion (Al +3 ) Control standard (10ug/ml) 10ug/ml USP limit for aluminum ion content

33 99mTc- COLD KIT VERSATILE MEANS OF ENABLING THE PREPARATION OF A WIDE VARIETY OF PRODUCTS. GLASS VIAL WITH SPECIFIED QUANTITIES OF REAGENTS ( FREEZE DRIED). LONG SHELF-LIFE ( > 12 MONTHS). REDUCING AGENT: TIN (STANNOUS CHLORIDE). ANTIOXIDANT ( ASCORBIC OR GENTISIC ACID). REDUCTION FROM OXIDATION STATE (VII) TO LOWER OXIDATION STATE ( III OR IV).

34 REAGENT VIAL OR «KIT»

35 RADIOCHEMICAL PURITY FRACTION OF THE TOTAL RADIOACTIVITY IN THE DESIRED CHEMICAL FORM IN THE RADIOPHARMACEUTICAL. RADIOCHEMICAL IMPURITIES ARISE FROM DECOMPOSITION DUE TO : ACTION OF SOLVENT CHANGE IN TEMPERATURE OR ph. OXIDIZING OR REDUCING AGENTS RADIOLYSIS OR LIGHT.

36 RADIOCHEMICAL PURITY FREE 99mTcO4-, HYDROLYZED 99mTc. NUMBER OF ANALYTICAL METHODS: PRECIPITATION PAPER, THIN-LAYER, GEL CHROMATOGRAPHY. PAPER AND GEL ELECTROPHORESIS. HIGH PERFORMANCE CHROMATOGRAPHY.

37 ASCENDING CHROMATOGRAPHY

38 Radiochemical purity Na 99m TcO 4 95% 99m TcO 2 * H 2 0 (colloid) 5% Solvent front Origin

39 CHROMATOGRAPHIC ANALYSIS SYSTEM A : 99mTco4 migrates at the solvent front, 99mTc-MDP and 99mTcO2 at the origin. SYSTEM B : Only 99mTcO2 remains at the origin.

40 ELECTROPHORESIS CHAMBER Direct current applied, enabling migration of radioactive ions applied to the cellulose acetate medium.

41 CHEMICAL PURITY FRACTION OF THE MATERIAL IN THE DESIRED CHEMICAL FORM. PRINCIPAL UNDESIRABLE CHEMICAL CONTAMINANT IN A 99mTc- GENERATOR ELUATE: ALUMINUM.

42 BIOLOGICAL TESTS STERILITY : ALL PREPARATIONS MUST BE STERILIZED. APYROGENICITY: PYROGEN: POLYSACCHARIDES OR PROTEINS. CHILLS, MALAISE, FATIGUE, NAUSEA. RABBIT TEST, LAL TEST. TOXICITY

43 Compounding with Tc-99m Many oxidation states +7 stable (Na +1 :Tc +7 :O 4-8 ) Kits contain stannous chloride (Sn +2 ) Reducing agent Liquid Sn +2 very susceptible to oxidizing When Tc99m is in lower than +7 you must have a ligand available

44 Tc99m-sestamibi commercially available kit 2-methoxy isobutyl isonitrile copper tetrafluoroborate 1mg (ligand) Sodium citrate dihydrate 2.6mg (trans-chelate) L-cysteine HCL monohydrate 1mg (accelerator ) Mannitol 20mg (solubilizing agent ) Stannous Chloride mg (reducing agent)

45 Tc99m-sestamibi Reconstituted w/150mci TcO4- in 3mls Boil for 10 minutes, cool, QC QC: Baker-flex Aluminum Oxide plastic TLC plates using 100% ethanol as the solvent phase % Tc99m-sestamibi= top counts/ total counts Package insert procedure takes about 40 minutes

46 Tc99m-tetrofosmin commercially available kit Commercially available kit Tetrofosmin 0.23mg (ligand) Stannous chloride 30ug (reducing agent) D-gluconate 1mg (trans-chelate) Sodium bicarbonate 1.8mg (buffer)

47 Tc99m-tetrofosmin Reconstitute with 240mCi of TcO4- in a volume of 8mls with a venting needle is very important for stability Tc99m concentration is very important for stability Incubate at room temperature for 15min.

48 QC testing of 99m Tc-tetrofosmin Instant thin-layered chromatography (ITLC) Recommended by the manufacturer ITLC/SG strip (20cm x 1cm) 35:65 acetone:dichloromethane mixture as mobile phase Drawbacks: Toxic solvent dichloromethane Factors affecting QC results: sample drop size, the condition of the SG strip, the freshness and the exact ratio of acetone:dichloromethane requires 20 to 50 minutes

49 SECULAR EQUILIBRIUM Secular Equilibrium Parent half-life>>> daughter half-life

50 Rubidium-82 (CardioGen-82 ) Generator produced from the parent Sr-82 (T1/2 = 25 days) (Secular equilibrium) T1/2 = 75 sec Rubidium cation Na-K ATPase pump Dose: 50-60mCi infused over seconds Imaging 90sec post Automated infusion

51 Rubidium-82 (CardioGen-82 ) Generator useful for 4-6 weeks Available w/ three month notice to Bracco Strontium-82 generator T1/2=25 days, (Rb-82 75sec) Disadvantage: High energy (3.15 Mev max) travels farther from site of origin (12mm) before annihilation, decreasing intrinsic resolution.

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