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 μg 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 μg of a different anti-D immunoglobulin product.