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.