Summary
The binding of ritodrine HCl in whole plasma from healthy nonpregnant women, parturients and matched umbilical venous plasma and in solutions of HSA and α1-AGP has been studied by equilibrium dialysis. Binding to plasma from nonpregnant subjects and HSA was independent of ritodrine concentration over a wide range.
The free fraction in plasma was high and significantly different between groups of nonpregnant (α=0.64), parturient (α=0.68) and matched umbilical venous plasma (α=0.75). It would seem that variability in transplacental transfer of ritodrine, as a result of plasma binding fluctuations, will be minor.
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References
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Gross, A.S., Brown, K.F. Plasma protein binding of ritodrine at parturition and in nonpregnant women. Eur J Clin Pharmacol 28, 479–481 (1985). https://doi.org/10.1007/BF00544372
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DOI: https://doi.org/10.1007/BF00544372