Ritodrine pharmacokinetics in twin pregnancy patients.

OBJECTIVES

To establish a rational ritodrine therapy in relation to serum ritodrine concentration, we examined 14 twin pregnancy patients and determined their pharmacokinetic data.

METHODS

We measured serum concentrations of ritodrine in twin pregnancy patients using high-performance liquid chromatography (HPLC).

RESULTS

The twin pregnancy patients all exhibited linear ritodrine pharmacokinetic profiles. There was a statistically significant but slight negative correlation between gestation period and ritodrine clearance (y=-0.038x+2.75, r=0.349, p<0.001) among all patients. However, when analyzed on an individual basis, there was a high correlation found in three of the 14 patients.

CONCLUSION

Due to a decrease in total body clearance in three of the 14 patients, overall serum concentration of ritodrine increased at the end of the pregnancies. To further characterize ritodrine kinetics, additional studies are needed to determine an effective and safe therapy for ritodrine use in twin pregnancy patients.