Pharmacokinetics of ritodrine administered intravenously: recommendations for changes in the current regimen.
Am J Obstet Gynecol
; 162(2): 429-37, 1990 Feb.
Article
em En
| MEDLINE
| ID: mdl-2309826
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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ritodrina
/
Gravidez
Limite:
Female
/
Humans
Idioma:
En
Revista:
Am J Obstet Gynecol
Ano de publicação:
1990
Tipo de documento:
Article