Abstract | OBJECTIVE: Intravenous magnesium sulfate is widely used in obstetrics for the treatment of both preterm labor and preeclampsia. Although therapeutic levels of total magnesium have been proposed, the levels remain controversial. Because the active form of magnesium is the free or ionized form, it is essential to determine whether ionized magnesium and total magnesium levels are highly correlated in vivo. We sought to examine the correlation between ionized magnesium and total magnesium under basal and therapeutic conditions and to define the initiation and elimination pharmacokinetics of both forms during intravenous magnesium sulfate infusion. STUDY DESIGN: RESULTS: Baseline levels of total magnesium and ionized magnesium were not different between patients with preterm labor and with preeclampsia. Among patients with preeclampsia, although not patients with preterm labor, the initial apparent volume of distribution was significantly smaller for total magnesium than for ionized magnesium (16,397 +/- 1441 vs 23,856 +/- 2745 mL, respectively; P =.03), and the elimination half-life was greater for total magnesium as compared to ionized magnesium (707 +/- 160 vs 313 +/- 29 minutes;P <.05). Linear regression analysis demonstrated a lack of correlation between ionized magnesium and total magnesium during the pretreatment period and during the steady state infusion for both preterm labor and preeclampsia. CONCLUSION:
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Authors | Evan B Taber, Lily Tan, Conrad R Chao, Marie H Beall, Michael G Ross |
Journal | American journal of obstetrics and gynecology
(Am J Obstet Gynecol)
Vol. 186
Issue 5
Pg. 1017-21
(May 2002)
ISSN: 0002-9378 [Print] United States |
PMID | 12015530
(Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Ions
- Tocolytic Agents
- Magnesium Sulfate
- Magnesium
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Topics |
- Adult
- Female
- Half-Life
- Humans
- Infusions, Intravenous
- Ions
- Magnesium
(administration & dosage, blood, pharmacokinetics)
- Magnesium Sulfate
(therapeutic use)
- Obstetric Labor, Premature
(drug therapy, metabolism)
- Pre-Eclampsia
(drug therapy, metabolism)
- Pregnancy
- Tocolytic Agents
(therapeutic use)
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