Open AccessPharmacokinetics of 250 μg anti‐D IgG in the third trimester of pregnancy: An observational study
Author(s) -
TIBLAD ELEONOR,
WIKMAN AGNETA,
RANE ANDERS,
JANSSON YVONNE,
WESTGREN MAGNUS
Publication year - 2012
Publication title -
acta obstetricia et gynecologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 102
eISSN - 1600-0412
pISSN - 0001-6349
DOI - 10.1111/j.1600-0412.2012.01377.x
Subject(s) - medicine , pregnancy , pharmacokinetics , observational study , antibody , population , prospective cohort study , gestation , obstetrics , outpatient clinic , fetus , immunology , genetics , environmental health , biology
Objective. We present a pharmacokinetic study evaluating a single intramuscular dose of 250 μg anti‐D immunoglobulin in the third trimester of pregnancy. The aim of the study was to determine the kinetic profile and duration of detectable levels of anti‐D. Design. Prospective observational study. Setting. Antenatal outpatient clinic. Population. Healthy Rhesus D (RhD)‐negative pregnant women with an RHD ‐positive fetus. Methods. Serial plasma anti‐D quantitations following antenatal administration of anti‐D immunoglobulin were performed using flow cytometry. Kinetic profiles for anti‐D levels were generated from the concentration values at predetermined sampling time points. The half‐lives were calculated by linear regression analysis. Main outcome measures. Time vs. concentration profile, half‐life and anti‐D concentration ≥1 ng/mL close to term. Results. The maximal plasma concentration of anti‐D was usually seen at 3–10 days postinjection, with a median value of 25 ng/mL. The half‐life varied between individuals, with a median of 23 days. We found detectable levels of anti‐D IgG within two weeks of parturition in 11 of 12 women. Conclusions. The preparation of anti‐D immunoglobulin used in the present study, if administrated in pregnancy week 28–30, is associated with detectable levels of anti‐D in most women at the time of delivery. Although the half‐time is 23 days, it is uncertain whether all mothers have adequate anti‐D concentrations at term. Alternative strategies may be evaluated in the future, with repeated administration of antenatal prophylaxis at term rather than conventional postpartum administration of anti‐D.