UKRG Handbook    ADVERSE REACTIONS AND DEFECTIVE RADIOPHARMACEUTICALS

UNANTICIPATED BIODISTRIBUTION OF RADIOPHARMACEUTICALS

Five reports were received where the biodistribution of the radiopharmaceutical in the patient was not that normally expected, but there was no evidence to suggest that the product did not meet its specifications.

Two reports concerned increased non-osseous uptake of oxidronate. In the first case, there was no skeletal uptake in a patient being investigated for hypercalcaemia following malignancy. A skeletal survey 3 days later confirmed widespread metastatic deposits. Five other patients injected with with oxidronate from the same vial did show bone accumulation, suggesting that the radiopharmaceutical was satisfactory. It transpired that the patient had been treated with a biphosphonate and this was considered to be the likely cause for the non-visualisation of the skeleton. In the second case the majority of uptake was in the liver with a small amount of bone uptake. There was also considerable soft tissue uptake. The patient was on long-term dialysis for chronic renal failure and at the time of imaging was very acidotic and had a markedly elevated serum potassium. The appearance may therefore have been due to the patient's metabolic state. Other patients who had been injected from the same vial showed expected bone uptake.

There were two reports of increased accumulation in the salivary glands of patients undergoing cerebral blood flow studies. In one case technetium bicisate had been used and it was confirmed that there was not a problem with radiochemical purity, thus precluding the possibility that the appearances were due to pertechnetate. The other study was performed with technetium exametazime and again radiochemical purity was satisfactory. No explanation of salivary gland uptake was put forward.

There was a problem with technetium DMSA in which five patients all showed liver and spleen uptake that compromised the quality of the images. The injections had been obtained from two different vials. Other vials from the same batch had been previously used without problem. It is known that technetium can form a variety of complexes with DMSA and that physiological conditions can affect distribution. It was not clear from the available information what was the cause of the problem in these reports.

Return to Radiopharmacy Handbook Index