Raymond N. Dansereau

Increasing the radiochemical purity of 99mTc sestamibi commercial preparations results in improved sensitivity of dual-phase planar parathyroid scintigraphy.

BackgroundPoor results for dual-phase parathyroid scintigraphy have recently prompted increased use of dual-tracer imaging. We noticed that seminal studies used higher radiochemical purity than provided by current commercial preparations meeting US Pharmacopea (USP) specifications (90% of technetium bound to sestamibi). We surmised that the presence of unbound Tc (non-MIBI tracer) might hamper dual-phase detection that is dependent on rapid wash-out of technetium from thyroid tissue. PurposeTo test the hypothesis that reducing non-MIBI tracer will enhance thyroid wash-out and improve sensitivity of dual-phase imaging. MethodsStarting in April 2003 we decreased the technetium to sestamibi ratio. This resulted in a significant decrease of non-MIBI tracer from 8.1±2.2% (SD) (group 1, n=42) to 3.5±1.1% (group 2, n=47) (P<0.05 t-test). We performed a retrospective review of 89 patients with primary hyperparathyroidism who underwent imaging and subsequent surgery. The pathological findings served as the ‘gold standard’. ResultsScanning detected 21/39 diseased glands (sensitivity=54%) in group 1 patients. In group 2 imaging detected 38/45 diseased glands (sensitivity=84%). An improvement in sensitivity (P<0.01) was achieved by modifying the radiopharmaceutical preparation. ConclusionsElevated levels of non-MIBI tracer in Tc-MIBI commercial preparations result in persistent thyroid background activity that may interfere with detection of parathyroid pathology. Achieving a higher degree of radiochemical purity (at least 95% bound, 5% impurities) than required by USP may be needed for optimal results. The large variation in sensitivity reported in the literature may be related in part to non-uniform radiopharmaceutical preparation.

Clinical production of pharmaceutical grade Tc-99m dextran 70 for lymphoscintigraphy

Lymphoscintigraphy is an established means to determine the lymphatic drainage patterns from malignant tissues and edematous extremities. Unfortunately, there are no commercially available dedicated radiopharmaceuticals labeled for use in lymphoscintigraphy studies. The authors report a simple way to extemporaneously compound pharmaceutical-grade Tc-99m dextran 70 to meet this need. Pharmaceutical-quality Tc-99m dextran 70 injection is prepared by a simple rapid method from drug intermediates that are marketed as parenteral drug products. The radiolabeling process yields a product of high radiochemical purity, with good in vitro and in vivo stability. The authors illustrate the use of this product in a patient with melanoma to show the lymphatic drainage pattern before surgery. The method described permits rapid compounding of Tc-99m dextran 70 injection from drug components that are intended for parenteral administration. Tc-99m dextran 70 provides the option of performing lymphoscintigraphy in any clinical nuclear medicine setting.

A Unique Drug Distribution Process for Radium Ra 223 Dichloride Injection and Its Implication for Product Quality, Patient Privacy, and Delineation of Professional Responsibilities

On May 15, 2013, Bayer Healthcare Pharmaceuticals announced that it had received marketing approval for the therapeutic radioactive medication radium Ra 223 dichloride injection (Xofigo; Ra 223). The product acquisition and distribution process for hospital-based nuclear pharmacies and nuclear medicine services is unlike any other. The product is distributed as a low-risk compounded sterile preparation through a single compounding nuclear pharmacy located in Denver, Colorado, pursuant to a prescription. This model for drug distribution and delivery to the user institution has implications for product quality, patient privacy, and delineation of professional responsibilities.

Development of a new coated-bead dosage form of sodium iodide I-131

Abstract Sodium iodide I-131 is a commonly used radiopharmaceutical agent m the diagnosis and treatment of various thyroid conditions. The USP recognizes an aqueous solution and a capsule dosage form of sodium iodide I-131. The sodium iodide I-131 solution presents significant radiation hazards associated with spills and inhalation of volatile components. The capsule dosage form restricts the dosing flexibility and often requires that the patient take several capsules. This paper describes the development of a stabilized solid dosage form of sodium iodide I-131. The non-radioactive species was used in this study because it possesses the physical and chemical properties of the radioactive compound, but without radiation hazards. The sodium iodide was dissolved in a polymeric film and applied to nonpareil beads by conventional fluid-bed technology. The film coating protected the sodium iodide from degradation by environmental factors. The bead dosage form offers the physician and pharmacist infinite dosing flexibility because the specified dose can be filled into a single hard-gelatin capsule before dispensing. This dosage form also minimizes the hazards associated with spillage and overcomes the volatility problem associated with the solution dosage form.

A pharmaco-scintigraphy study of riboflavin 5'-phosphate sodium capsules (1 vs. 4)

Abstract The comparative in-vivo disintegration, gastric emptying and bioavailability of 41 mg radiolabeled riboflavin 5′-phosphate sodium capsules administered as a single hard gelatin capsule or as four capsules was evaluated in human subjects. A total of 41 mg of riboflavin 5′-phosphate sodium and 7 MBq of technetium sulfur colloid were incorporated in a single gelatin capsule or the same dose was administered in four capsules. A randomized crossover design was conducted in eight subjects under fasting conditions. Capsule disintegration and gastric emptying was measured by γ scintigraphy and the relative amount of riboflavin excreted in the urine was measured by HPLC. The in-vivo disintegration time and gastric emptying of the four capsules was significantly faster than for the one capsule. The bioavailability of the four capsule regimen was 16.5 versus 11.2% for the one capsule. The amount of riboflavin excreted in the urine in the 0–2 h interval was significantly greater for the four versus one capsule. The in-vivo performance of one 41 mg riboflavin 5′-phosphate sodium capsule is significantly different than the equivalent dose administered in four capsules. Further studies are needed to understand the underlying mechanism for the difference between the regimens.

Hospital Nuclear Pharmacy—A Comparison of Physician and Pharmacist Practice

OBJECTIVE: Nuclear pharmacy is practiced in every hospital with a nuclear medicine clinic. Pharmacists control this practice in fewer than four percent of these institutions. The authors wish to bring to the attention of hospital pharmacists an area of practice in which they can make a significant contribution to the state of pharmacy practice. METHOD: The current state of the physician practice of nuclear pharmacy is described and compared with the accepted standards of pharmacy practice. CONCLUSIONS: Hospital pharmacists can improve pharmaceutical care administered in nuclear medicine by their participation in nuclear pharmacy practice and by the application of hospital pharmacy practice standards. It is also suggested that nuclear pharmacy should be integrated into the pharmacy curriculum at schools of pharmacy.