Preparation of 99m Tc-levetiracetam intranasal microemulsion as the first radiotracer for SPECT imaging of the Synaptic Vesicle Protein SV2A.

Selective receptors imaging using gamma emitting radiopharmaceuticals allows accurate diagnosis and follow up of many brain related disorders. Levetiracetam, a selective SV2A receptor antiepileptic, was successfully radiolabeled using ^99m Tc. Different conditions affecting the labelling process were studied and optimum radiochemical yield of 89.8% was obtained. ^99m Tc-levetiracetam was effectively formulated and characterized as microemulsion with particle size of 16.34 ± 5.58 nm and polydispersity index of 0.382 ± 0.05. Parallel biodistribution studies were performed comparing brain targeting efficiency of I.V ^99m Tc-levetiracetam solution, I.N ^99m Tc-levetiracetam solution and I.N ^99m Tc-levetiracetam microemulsion. Brain radioactivity uptake and brain/blood uptake ratio for I.N ^99m Tc-levetiracetam microemulsion were higher than the other two routes at all time intervals. Such results present intranasal ^99m Tc-levetiracetam microemulsion as the first SPECT tracer for imaging SV2A receptor.
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