Pharmacokinetics of ritodrine administered intravenously: Recommendations for changes in the current regimen
| Autor: | Michael Krew, Steve N. Caritis, Jye Ping Chiao, Raman Venkataramanan, Marilyn J. Darby |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Volume of distribution
Plasma clearance Metabolic Clearance Rate business.industry medicine.drug_class Obstetrics and Gynecology Muscle relaxant Drug Administration Schedule Regimen Pharmacokinetics Pregnancy Anesthesia Ritodrine Humans Medicine Distribution (pharmacology) Female Constant infusion Infusions Intravenous business medicine.drug |
| Zdroj: | American Journal of Obstetrics and Gynecology. 162:429-437 |
| ISSN: | 0002-9378 |
| DOI: | 10.1016/0002-9378(90)90401-r |
| Popis: | We define the pharmacokinetics of ritodrine in 13 pregnant women who received the drug intravenously. With constant infusion of 50 micrograms/minute, steady state ritodrine concentrations reached 28 +/- 11 ng/ml (SD) with a range of 15 to 45 ng/ml. This wide variation is a result of differences in plasma clearance, which ranged from 1.0 to 3.3 L/min, mean 1.94 +/- 0.71 L/min. The apparent volume of distribution was 6.95 +/- 3.54 L/kg, indicating that ritodrine is extensively bound to extravascular tissue. When an infusion of ritodrine is stopped, plasma concentrations fall rapidly initially with a distribution half-life of 5.9 +/- 6.0 minutes. After the initial rapid fall, plasma concentrations decrease more slowly with a mean disposition half-life of 156 +/- 51 minutes. On the basis of the pharmacokinetic parameters defined, we recommend that the current infusion regimen for ritodrine be changed. The infusion rate of ritodrine should start at 50 micrograms/minute rather than 100 micrograms/minute. The maximal infusion rate of 350 micrograms/minute should be increased and once labor is inhibited, the infusion rate should be reduced. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|