Pharmacodynamic properties
Pharmacotherapeutic group: Paramagnetic MRI contrast medium, ATC Code: V08C
A05
Mangafodipir is a chelate containing the metal manganese - which has paramagnetic
properties and is responsible for the contrast enhancement effect in MRI - and
the ligand fodipir (dipyridoxyl diphosphate). Manganese is preferentially taken
up by normal liver parenchyma and also in the pancreas so that contrast enhancement
between abnormal and normal tissue can be expected.
The effect of mangafodipir is to shorten the longitudinal relaxation time (T1)
of targeted tissues during MRI, leading to an increase in signal intensity (brightness)
of, for example, pancreas and liver parenchyma. Enhancement in both organs is
near maximal for up to approx. 4 hours after the end of administration. Lesion-related
enhancement of certain types of lesions, such as liver metastases and hepatocellular
carcinomas, may be detectable for up to 24 hours. Clinical studies have demonstrated
that mangafodipir facilitates the detection of liver lesions in patients with
such lesions.
TESLASCAN is isotonic with blood and normal body fluids.
Pharmacokinetic properties
Mangafodipir trisodium is metabolised (dephosphorylated) and manganese
ions are released from the mangafodipir by exchange with plasma zinc (mainly)
after intravenous administration. Manganese and the ligand (fodipir), which
have different pharmacokinetics, are eliminated by different routes.
The mean initial plasma half-life of manganese is 20 minutes or less, with
significant uptake into the liver, pancreas, kidneys and spleen. The initial
plasma half-life of ligand is about 50 minutes. The volume of distribution for
manganese is between 0.5 and 1.5 l/kg, and for fodipir 0.17 to 0.45 l/kg. Following
its metabolism, nearly all of the ligand (fodipir) is excreted in urine within
24 hours, with negligible amounts being eliminated via the faeces. About 15-20
% of the manganese is eliminated in the urine within the first 24 hours, most
of the remainder is excreted in the faeces over the following 4 days.
In whole human blood in vitro, the protein binding of manganese is approximately
27 % but binding of fodipir to protein is negligible.
Preclinical safety data
Non-clinical studies reveal no special hazard for humans based on conventional
studies of genotoxicity, safety pharmacology and validating kinetics and metabolism.
Relevant adverse effects from repeated dose toxicity studies were liver toxicity
(cholangiohepatitis) observed at relatively low dosages in dogs, while sufficient
margins of safety were determined in rats and monkeys.
Mangafodipir is teratogenic in rats; it causes increased foetal skeletal abnormalities
when given daily by intravenous injection to female rats at dosages slightly
greater than clinical dosages. Embryo- and foetotoxicity has been observed
in rabbits.
Last updated on RxList: 3/3/2009