Hj. Pieniaszek et al., Human moricizine metabolism. II. Quantification and pharmacokinetics of plasma and urinary metabolites, XENOBIOTICA, 29(9), 1999, pp. 945-955
1. The metabolism of moricizine HCl was studied in 12 male volunteers dosed
with 250 mg (300 mu Ci) C-14-radiolabelled drug.
2. Moricizine was biotransformed to many metabolites in humans (at least 35
plasma and 51 urine metabolites).
3. Urine and faecal combined mean (range) recovery accounted for 90.2 % (73
.4-101.6 %) of the administered radioactivity, with most of the recovered r
adioactivity present in faeces (mean 58.4 %; range 45.6-64.7 %). Mean (rang
e) urinary recovery was 31.8 % (26.2-36.9 %), with < 1 % of the dose recove
red as intact moricizine, and no one metabolite accounting for > 2.5 % of t
he dose.
4. Total radioactivity (TR) plasma t(1/2) was 85.2 h, while that for morici
zine was 2.4 h. Mean half-lives for plasma metabolites ranged from 2.9 to 2
3.6 h. The largest portion (11 %) of TR AUC (area under the plasma concentr
ation-time curve) was attributed to 2-amino-10-glucuronophenothiazine. Each
of the other metabolites accounted for less of the TR AUC than parent drug
except for two unidentified peaks which had comparable areas (similar to 5
% of the total radioactivity area).
5. Two identified moricizine metabolites, 2-amino-10-(3-morpholinopropionyl
) phenothiazine and ethyl [10-(3-aminopropionyl) phenothiazin-2-yl] carbama
te, possess the structural characteristics proposed for class 1 anti-arrhyt
hmic activity (pendant amine functionality) and have plasma half-lives 4-7-
fold longer than moricizine.