Radiopharmaceuticals and Radiolabelled Drugs


Biotest Facility carries out studies on radioactive compounds in preclinical models for mainly two purposes; for testing radiopharmaceuticals and for tracing isotope-labelled drug products.


Our study service for radiopharmaceuticals is based on our classic in vivo pharmacology service, on top of which the isotope techniques are applied. These include safety and regulatory issues, and the training of dedicated personnel. We organise shipping of drug products and samples to Sponsor and other sites for labelling and analysis of samples. Analysis typically includes the formulation solution and samples from the in vivo phase. The facility and personnel are monitored according to national guidelines and legislation. Every study is approved by the national authorities before initiation, and the results of the supervision are reported to the national authorities after all high-risk phases of the study and after study termination.


The purpose of using radioactive medicine (radiopharmaceuticals) is to weaken malfunctioning cells by means of radiation. By using targeted radionuclide therapy (TRNT), a radiation dose can be applied to specific cells and to specific anatomical locations. Radium-223 used for the treatment of bone metastases (targeted alpha therapy, TAT) was the first α-emitter approved by FDA. The targeting of radiation can be facilitated by conjugation to peptides, antibodies, small molecules, or other polymers; the first regulatory-approved radiolabelled mAb was Yttrium-90-ibritumomab to treat non-Hodgkin lymphoma. At Biotest Facility we have the capacity, solid experience, and separate facility sections for conducting studies with radiopharmaceuticals.


The toxicity classification was recommended by the International Atomic Energy Agency (IAEA) to act as a guide to the procedures and facilities required for handling the radioactive substances. Radionuclides were divided in four classes according to radiotoxicity:

Group    I - high (e.g. 223Ra, 241Am)
Group   II - upper medium (e.g. 131I, 125I)
Group  III - medium and lower medium (e.g. 32P, 14C)
Group  IV - low (e.g. 3H, 35S)

Biotest Facility has the expertise and the infrastructure to handle compounds falling within any of the four radiotoxicity classes.


Radiolabelled compounds are used in mass-balance studies, where total fate of drug related material is investigated after in vivo administration, and depending on the analysis applied, the metabolic pathways of the drug are investigated. Other uses of radiolabelled drug products are in the determination of targeting and biodistribution of drugs, which can be detected by counting radioactive decay in dissected tissues or by various imaging techniques. In a mass-balance study, the animals are placed in metabolic cages for a brief period, and faeces and urine are separated, collected, and analysed. In these studies, the aim is to employ a radioactive label that preserves the physiochemical properties of the molecule to the best possible degree. Carbon-14 is often used for in this type of labelling.

Radiopharmaceuticals and radiolabelled drugs.
Biotest Facility is specialised in providing in vivo studies of radiopharmaceuticals and radiolabelled drug products.