The effects of selected antineoplastic agents on the labeling of erythrocytes with technetium-99m using the UltraTag RBC kit.

OBJECTIVE: Adverse affects of various drugs on the labeling efficiency of RBCs with 99mTc-pertechnetate have been known for several years. This study presents data on the ability of the UltraTag RBC kit to label RBCs with pertechnetate in the presence of various antineoplastic drugs. METHODS: Five different antineoplastic drugs, either alone or in combination, were incubated for 30 min at 37 degrees C with 2-mL samples of whole blood obtained from normal volunteers. Each sample was labeled with pertechnetate and the radiochemical purity determined according to the UltraTag RBC product package insert. Doxorubicin was specifically tested in molar ratios with stannous ion of greater than 1:1 to determine if there was any significant chelation effect that would affect the ability of the kit to label RBCs. In addition, patients were given a bolus injection of doxorubicin and a blood sample was drawn at 30 min to test whether the metabolites had any effect on labeling. RESULTS: The ability of the UltraTag RBC kit to label RBCs with pertechnetate was not adversely affected by the antineoplastic drugs when they were present alone or in combination. Likewise, doxorubicin metabolites did not interfere with the labeling efficiency of 99mTc RBCs using the UltraTag RBC kit. Molar ratios of doxorubicin-to-tin that exceeded 1:1 also had no adverse effects on the labeling efficiency of the UltraTag RBC kit. CONCLUSION: When performing nuclear medicine exams involving the labeling of RBCs with pertechnetate on patients who have received doxorubicin, as well as certain other antineoplastic agents, a high RBC labeling efficiency can be obtained if the UltraTag RBC kit is used.

Unexpected stomach uptake of technetium-99m-MDP.

Two pediatric cases are described in which the results of each patient's bone scan demonstrated abnormal stomach uptake. There have been a number of reports in the literature describing stomach uptake of bone agents, however, it is an uncommon finding.

Problems associated with the clinical use of radiopharmaceuticals: a proposed classification system and troubleshooting guide.

Problems associated with the clinical use of radiopharmaceuticals can usually be classified into one of four categories: unusual imaging results, adverse reactions, unique difficulties encountered in special patient populations, and quality assurance failures. Each of these problem areas is briefly described and a guide for troubleshooting such problems is presented.

Clinical radiopharmacy: principles and practices.

On the average, radiopharmacists spend about 17.2% of their time in clinical activities if their practice setting is in an institution, and about 8.5% of their time if their practice setting is in a centralized nuclear pharmacy. A recent survey of radiopharmacists was conducted to determine: (1) the percentage of time they spend engaged in selected activities, and (2) the specific clinical activities in which they are involved. A few radiopharmacists spend as much as 50% of their time in clinical activities, but most spend only 5% to 20% of their time. Some of the clinical activities involve direct interactions with patients, such as explaining the reasons for administering the radioactive material or actually administering the dose. Other clinical activities are indirect, such as reviewing charts before or after studies and making recommendations to other health care professionals. About half of the pharmacists surveyed see a need for increasing their clinical activities. The need to maximize the time involved in providing pharmaceutical care is discussed and several patient-care activities/responsibilities are proposed.

A study of the concept of non-radioactive unit-dosed reagent kits [cold unit doses (CUDs)] as an efficient and cost-saving method for 99mTc radiopharmaceutical preparation.

Traditionally, when preparing 99mTc-labeled radiopharmaceuticals, [99mTc]pertechnetate is added to the entire contents of a vial of reagent kit, and patient doses are subsequently withdrawn from the vial. This technique of compounding can be potentially wasteful for two reasons: (1) once reconstituted with 99mTc, most reagent kits have a relatively short shelf-life, and thus the entire contents may not be used before expiration and (2) due to a need to conserve radioactivity in many hospitals, enough [99mTc]pertechnetate is added to the reagent kit in order to retrieve only 1-2 patient doses, even though adequate chemicals (ligand, reducing agent, etc.) are present in the reagent kit to supply as many as 5-10 doses. Hence, a method for optimizing the efficient use of reagent kits would be desirable. The purpose of this study was to determine the feasibility of unit-dosing non-radioactive reagent kits and storing these cold unit doses (CUDs) for eventual labeling with 99mTc. To evaluate this concept, unit doses were prepared from reagent kits of medronate (MDP) and pentetate (DTPA). The specific variables studied in this research were the effects of storage time, storage temperature and reconstitution volume (dilution) on the unit doses. These effects were monitored by measuring the radiochemical and biodistribution properties of the unit doses following their final reconstitution with [99mTc]pertechnetate. The labeling efficiency was determined using instant thin layer chromatograph (ITLC), and the biodistribution patterns of these radiolabeled CUDs were studied in mice. The results showed the MDP- and DTPA-CUDs stored at -18 degrees C retained the properties which resulted in acceptable radiochemical purity and biodistribution in mice for as long as 30 days. On the other hand, the radiochemical purity of MDP and DTPA unit doses stored at 25 degrees C deteriorated rapidly. Mean radiochemical purities as low as 0.58-19.4% were observed on day 30. Altered biodistributions were observed in a manner consistent with the decreased labeling efficiencies. The CUDs of lower dilution (3 mL) appeared to be more stable than the CUDs of higher dilution (10 mL). However, the effect of reconstitution volume was much less significant than the temperature effect on the CUDs. In conclusion, the concept of unit-dosing non-radioactive reagent kits appears to provide an efficient and cost-saving method for preparing infrequent and emergency radiopharmaceutical doses. The study also showed that the storage temperature of these unit doses is critical to the success of the procedure. The volume of reconstitution has a minimal impact on the stability of CUDs if stored at the appropriate temperature.

Pharmacokinetic evaluation of technetium-99-metallothionein-conjugated mouse monoclonal antibody B72.3 in rhesus monkeys.

These studies were conducted to determine the biodistribution and pharmacokinetics of [99mTc]metallothionein-conjugated B72.3 ([ Tc]MT-B72.3) in Rhesus monkeys (Macaca mulatta) that were performed as part of the preclinical evaluation of [Tc]MT-B72.3. The B72.3-MT conjugate was studied at three doses of B72.3 ranging from 0.03 mg/kg to 1 mg/kg to determine whether a relationship existed between the dose of total antibody administered intravenously and the biodistribution and clearance of the radiolabeled protein. Results indicated that [Tc]MT-B72.3 distributes rapidly to central body cavity organs and that there was no difference in the rate of blood elimination for the three doses of B72.3 studied. The terminal phase of blood elimination was found to be 26.2 +/- 6.1 hr for the combined groups of monkeys. Approximately one-half of injected 99mTc activity was recovered in the urine within 24 hr. A second purpose of these studies was to evaluate the overall immunogenicity of the mouse monoclonal B72.3 IgG1 antibody in Rhesus monkeys. These results demonstrated that a single i.v. exposure to mouse monoclonal B72.3 at doses of 0.3 mg/kg or greater elicited antibody production to B72.3 in Rhesus monkeys within 3 wk. Analysis of [Tc]MT-B72.3 biodistribution and clearance in monkeys with circulating levels of antibodies to B72.3 (immunized monkeys) revealed that the liver was the primary site of clearance of the presumed immune complex and that blood elimination was greatly accelerated.

Technetium antimony sulfur colloid scintiscan in selective lymph node dissection for malignant melanoma.

Lymphoscintigraphy with Technetium antimony sulfur colloid (TASC) was used in four patients with malignant melanoma to identify the pattern of lymphatic drainage, allowing selective lymph node dissection. TASC is safe and predictive of lymph node drainage patterns. Using this technique allows visualization of multiple tiers of lymph nodes in 2 to 6 hours.

Common uses of nonradioactive drugs in nuclear medicine.

A variety of nonradioactive pharmaceuticals commonly used in patients who receive nuclear medicine diagnostic tests are described. Nonradioactive drugs used in thyroid, brain, hepatobiliary, cardiac, renal, Meckel's diverticulum, gallium, adrenal, and hematological studies are described. Pharmaceutical necessities used as disinfectants, diluents, and anticoagulants are also described. Hospital pharmacists should be familiar with the uses of commonly prescribed nonradioactive drugs in nuclear medicine studies.

Effect of technetium Tc 99m pertechnetate on bacterial survival in solution.

Survival of Staphylococcus epidermidis (10(2) organisms/ml) in solutions containing various levels of radioactivity was assessed. Six test preparations contained nonbacteriostatic 0.9% sodium chloride solution; four of these contained technetium Tc 99m pertechnetate (99mTcO-4) in various quantities (80, 250, 500, and 750 mCi). A fifth contained technetium that had decayed to an essentially nonradioactive form, and a sixth contained 0.9% sodium chloride solution only. Each of the six 20-ml solutions was inoculated with 2 ml of single-strength trypticase soy broth (TSB) containing 10(3) organisms/ml. At various times up to 12 hours after inoculation, 1-ml aliquots of each test solution were withdrawn and passed through 0.22-micron filters, thereby preventing further irradiation of the filtered organisms. The filters were incubated in single-strength TSB at 37 degrees C, and samples were examined for turbidity at 24, 48, and 72 hours. After 24 hours, 25 of the 36 sample tubes showed turbidity; after 48 hours, the turbid samples totaled 28. Bacteria in the two nonradioactive solutions remained viable throughout the 12-hour sampling period. Accumulated doses of radiation obtained in the 250-, 500-, and 750-mCi samples inhibited bacterial growth. To be a valid quality-control measure, sterility monitoring of prepared radiopharmaceutical dosage forms may need to be performed concurrently with their preparation.

Post-traumatic pulmonary accumulation of Tc-99m sulfur colloid.

A case is reported in which accumulation of Tc-99m sulfur colloid in one lung occurred following trauma, although the lung remained clear radiographically. Another trauma case is mentioned in which the uptake was bilateral. The cause of this phenomenon is unclear; several potential mechanisms are discussed.

One hundred digitalis blood levels. A utilization review.

One hundred consecutive digitalis serum level determination requests and results were analyzed to evaluate the rational of ordering the test and utilizing the results at his hospital. Sixty-six percent of the reasons given for ordering the test were categorized as "acceptable". As many as 25% of physicians requesting the test considered digitalis levels as "routine" diagnostic tests in a patient taking these drugs. There were 12 levels within the potentially toxic range, 19 below the usual therapeutic range. The physicians modified their therapeutic management in 38 patients as a result of their knowledge of the digitalis level in blood. It is concluded that digitalis level determinations at this hospital are reasonably well utilized and that knowledge of the digitalis levels improve the accuracy of digitalis utilization in at least one third of the patients in whom this test is done.

Evaluation of written reinforcements used in counseling cardiovascular patients.

The acceptance and effectiveness of medication cards and booklets for cardiovascular patients were evaluated. Approximately one month after discharge counseling which included the written reinforcements, 22 out of 50 patients discharged from cardiothoracic surgery and cardiovascular medicine units were questioned to assess patient usage of the medication cards/booklets and patient knowledge of their particular drugs. All patients except one indicated that they had read the material after leaving the hospital, and many had read it more than once. The effectiveness of the material was found to be only partially acceptable when general and specific medical questions were asked. The names and uses of most of the drugs taken by the patients were identified correctly.