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Magnesium sulfate in eclampsia and pre-eclampsia: pharmacokinetic principlesJ F Lu et al. Clin Pharmacokinet. 2000 Apr. AbstractMagnesium sulfate (MgSO4) is the agent most commonly used for treatment of eclampsia and prophylaxis of eclampsia in patients with severe pre-eclampsia. It is usually given by either the intramuscular or intravenous routes. The intramuscular regimen is most commonly a 4 g intravenous loading dose, immediately followed by 10 g intramuscularly and then by 5 g intramuscularly every 4 hours in alternating buttocks. The intravenous regimen is given as a 4 g dose, followed by a maintenance infusion of 1 to 2 g/h by controlled infusion pump. After administration, about 40% of plasma magnesium is protein bound. The unbound magnesium ion diffuses into the extravascular-extracellular space, into bone, and across the placenta and fetal membranes and into the fetus and amniotic fluid. In pregnant women, apparent volumes of distribution usually reach constant values between the third and fourth hours after administration, and range from 0.250 to 0.442 L/kg. Magnesium is almost exclusively excreted in the urine, with 90% of the dose excreted during the first 24 hours after an intravenous infusion of MgSO4. The pharmacokinetic profile of MgSO4 after intravenous administration can be described by a 2-compartment model with a rapid distribution (a) phase, followed by a relative slow beta phase of elimination. The clinical effect and toxicity of MgSO4 can be linked to its concentration in plasma. A concentration of 1.8 to 3.0 mmol/L has been suggested for treatment of eclamptic convulsions. The actual magnesium dose and concentration needed for prophylaxis has never been estimated. Maternal toxicity is rare when MgSO4 is carefully administered and monitored. The first warning of impending toxicity in the mother is loss of the patellar reflex at plasma concentrations between 3.5 and 5 mmol/L. Respiratory paralysis occurs at 5 to 6.5 mmol/L. Cardiac conduction is altered at greater than 7.5 mmol/L, and cardiac arrest can be expected when concentrations of magnesium exceed 12.5 mmol/L. Careful attention to the monitoring guidelines can prevent toxicity. Deep tendon reflexes, respiratory rate, urine output and serum concentrations are the most commonly followed variables. In this review, we will outline the currently available knowledge of the pharmacokinetics of MgSO4 and its clinical usage for women with pre-eclampsia and eclampsia. Similar articles
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When administering mag sulfate to a client with preeclampsia the nurse understands that this drug is given to do which of the following?As soon as eclampsia is diagnosed, magnesium sulfate must be given to prevent seizures from recurring. If patients have preeclampsia with severe features, magnesium sulfate can be given to prevent seizures. Magnesium sulfate is given for 24 hours postpartum.
How is magnesium sulfate administered in preeclampsia?Magnesium sulphate is recommended as the first-line medication for prophylaxis and treatment of eclampsia. The loading dose is 4 g IV over 20 to 30 min, followed by a maintenance dose of 1 g/h by continuous infusion for 24 h or until 24 h after delivery, whichever is later.
When administering magnesium sulfate for what should the nurse assess the patient?Monitor for signs and symptoms of magnesium sulfate toxicity (ie. hypotension, areflexia (loss of DTRs), respiratory depression, respiratory arrest, oliguria, shortness of breath, chest pains, slurred speech, hypothermia, confusion, circulatory collapse).
What should I check before giving magnesium sulfate?Before repeating administration of MgSO4, check that: - Respiratory rate is at least 16 per minute. - Patellar reflexes are present. - Urinary output is at least 30 mL per hour over 4 hours.
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When administering magnesium sulfate to a client with preeclampsia the nurse understand that this drug is given to?
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