Radiopharmacy/Radiochemistry for Conventional Single-Photon Emitting and Therapeutic Radiopharmaceuticals

Abstract

Conventional agents for diagnostic single-photon emission imaging and for radionuclide therapy are mostly associated with radiopharmaceuticals labeled with technetium-99m and iodine radioisotopes. This category of radiopharmaceuticals still determines, to a great extent, the usual operations inside a conventional hospital radiopharmacy. Although this description is not universally accepted and can be certainly subjected to some revision, for the purpose of the present chapter, by “conventional radiopharmacy” is meant a laboratory for the preparation and quality control of radiopharmaceuticals that are produced using either commercial, lyophilized kit formulations or supplied as ready-to-use pharmaceutical preparations. It is implicitly assumed that radiopharmaceutical products belonging to this class of licensed drugs have been always approved by some regulatory authority and intended for a specific clinical application. Obviously, radiopharmaceuticals labeled with radionuclides other than technetium-99m or iodine radioisotopes, but that can be obtained through a kit formulation or as ready-to-use preparations, e.g., indium-111 pentetreotide (Octreoscan^®), radium-223 chloride (Xofigo^®), yttrium-90 ibritumomab tiuxetan (Zevalin^®), or rhenium-188 hydroxyethylidene diphosphonate (¹⁸⁸Re-HEDP), can be conveniently included into this category. Conversely, both diagnostic single-photon emitting and therapeutic radiopharmaceuticals that are produced in-house following an extemporaneous, unlicensed procedure (galenic or magistral preparations) will not be considered in this chapter. From the point of view of radiopharmacy requirements, this ensemble of radiolabeling reactions is fully equivalent to those employed for preparing tracers for positron emission tomography (PET) using cyclotron-produced radionuclides. In particular, according to still predominant regulations, extemporaneous therapeutic radiopharmaceuticals should be obtained strictly following the rules of good manufacturing practice (GMP).

Glossary

cGRPP

Current good radiopharmacy practice

GMP

Good manufacturing practice

GRPP

Good radiopharmacy practice

ITLC

Instant thin-layer chromatography

HEPA

High efficiency particulate air

MP

Mobile phase

QC

Quality control

QA

Quality assurance

SG

Silica gel

SOP

Standard operating procedure

SP

Stationary phase

SPECT

Single-photon emission tomography

PET

Positron emission tomography

RCP

Radiochemical purity

RNP

Radionuclidic purity

TLC

Thin-layer chromatography