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Tuesday, 11 December 2012

New Drug Approvals 2012 - Pt. XXVII - Choline C-11

On September 12, FDA approved Choline C-11, an intravenous radioactive diagnostic agent to be used as tracer during Positron Emission Tomography (PET) scan to help detect sites of recurrent Prostate Cancer (OMIM : 176807 ; MeSH : D011471) .

Prostate cancer is the most common cause of death from cancer in men over age 75, and is rarely found in men younger that 40. Unlike many other cancers, prostate cancer usually progresses very slowly. Sometimes the cancer cells may metastasize from the prostate to other parts of body. Overall, it is estimated to be the sixth leading cause of cancer-related death in men.

Choline is a naturally occurring component of the numerous Vitamin-B complex, and is necessary for normal cell structure and signalling. Choline C-11 is a radiolabeled synthetic analog of choline that releases a positron by beta decay which can be visualised by PET. Choline is rapidly taken up by the prostate cells and this allows the prostate to be imaged. 

Choline, a precursor molecule essential for the biosynthesis of phospholipids which are the structural components of cell membranes, as well as modulation of trans-membrane signalling. Increased activity of phospholipid synthesis has been associated with increased cell proliferation and the transformation process that occurs in tumour cells.
Choline C-11 is a positron emitting radiopharmaceutical that is used for diagnostic purpose in conjunction with PET imaging. The active ingredient is Choline C-11 and each millilitre of the injection contains 148 MBq to 1225 MBq of the active ingredient.

IUPAC Name (Choline) : 2-hydroxy-N,N,N-trimethylethanaminium
Canonical Smiles : [Cl-].[11CH3][N+](C)(C)CCO
Standard InChI : 1S/C5H14NO.ClH/c1-6(2,3)4-5-7;/h7H,4-5H2,1-3H3;1H/q+1;/p-1/i1-1;

Following intravenous administration, Choline C-11 distributes mainly to the pancreas, kidney, liver, spleen and colon. The radioactivity accumulated rapidly within the prostate and peak uptake appeared with in 5 mins following the administration. Choline C-11 undergoes metabolism resulting in the detection of 11C-betaine as the major metabolite in blood. The rate of excretion of Choline C-11 in urine was 0.014 mL/min.

Choline C-11 has been developed and marketed by Mayo Clinic.

Full prescribing information is found here.

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