Pharmacokinetics of Anti-D IgG in Pregnant RhD-negative Women

Objective: To assess the pharmacokinetics of anti-D IgG in pregnant Rhesus D-negative women after intramuscular and intravenous administration of 300 microg of Rhophylac.

Design: An open, randomised, multicentre study.

Setting: Seven gynaecological practices in Germany.

Sample: Fourteen RhD-negative pregnant women at risk of becoming Rhesus D immunised received study drug at 28th week of pregnancy either by intramuscular or intravenous route.

Main Outcome Measures: Anti-D IgG concentrations of serum samples obtained up to 11 weeks following antenatal Rhesus D prophylaxis were quantified by flow cytometry.

Results: Mean anti-D IgG concentrations after intravenous and intramuscular administration differed up to seven days post-injection, from two weeks onwards they were comparable to each other. Irrespective of the administration route, anti-D IgG in serum was detectable in all women up to at least nine weeks post-administration.

Conclusions: The serum concentrations of anti-D IgG measured after administration of Rhophylac were very similar to those obtained with 300 microg of a different anti-D immunoglobulin product.