exametazime: clinical use

Prescribing considerations

• Justify ionising-radiation exposure for each patient and keep exposure as low as reasonably achievable while obtaining adequate diagnostic information.
• Confirm pregnancy status where relevant and consider non-ionising alternatives if pregnancy is possible.
• Ensure good hydration and encourage frequent voiding after examination.
• Account for possible sodium exposure in patients following a controlled-sodium diet.
• Use only through authorised personnel in appropriately licensed clinical settings.

Contraindications and cautions

• Hypersensitivity to exametazime or any formulation excipient.
• Exercise particular caution in renal or hepatic impairment because radiation exposure may be increased.
• The cobalt-stabilised product is not recommended for children because its safety and effectiveness have not been established.

Monitoring

• Maintain immediate access to facilities and medicines for managing hypersensitivity or anaphylaxis.
• Check vial integrity, aseptic preparation, labelling, shielding and radiochemical purity before use.
• Apply local radiation-protection precautions for patients, staff, waste and potential contamination.

Clinical pharmacology

Technetium-99m exametazime is an uncharged lipophilic complex that rapidly crosses the blood–brain barrier and is retained sufficiently to map regional cerebral perfusion by SPECT. Unbound activity is cleared through hepatobiliary and renal routes; cobalt stabilisation does not appear to alter its in-vivo pharmacokinetics.

Formulation and product differences

• The selected product is a non-radioactive kit containing exametazime powder and a separate cobalt chloride stabiliser solution.
• It must be reconstituted with sodium pertechnetate technetium-99m, which is not supplied; the vial contents must never be injected before preparation.
• The cobalt-stabilised preparation has specific post-reconstitution storage, quality-control and use-window requirements.