Deanol acetamidobenzoate inhibits the blood‐brain barrier transport of choline

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Abstract
Competition by deanol (dimethylaminoethanol) with choline for uptake from the bloodstream into the brain was demonstrated by simultaneous intracarotid administration of carbon 14‐labeled choline with deanol (plus tritiated water and indium 113m, to calculate a brain uptake index) and by measuring the brain uptake of 14C‐labeled choline mixed with sera from rats pretreated with deanol (300 or 500 mg/kg 8 or 30 minutes earlier). The inhibition constant for inhibition of choline uptake by deanol (159 μM) was actually lower than the Michaelis constant for choline itself (442 μM); hence, the affinity of the carrier mechanism for deanol is at least as great as it is for choline. Deanol administration also elevated blood choline levels; thus, the effect of the drug on brain choline (and acetylcholine) levels is the result of the increase it produces in blood choline and the suppression it causes in choline uptake. These findings may explain discrepant results from laboratories seeking increases in brain acetylcholine or clinical improvement in patients with tardive dyskinesia after deanol treatment.