BACKGROUND: Recent evidence suggests that antepartum magnesium(Mg) may prevent acute brain injury and long-term neurodevelopmental disabilities in VLBW premature infants. The degree of neuroprotection correlates with higher than normal initial serum Mg levels (≥ 3.0 mEq/L). The many premature infants not exposed to antenatal Mg would not benefit from its protective effect. Conceivably, postnatal therapy with Mg could achieve neuroprotection. The purpose of this investigation was to determine whether higher than normal serum Mg levels could be safely and effectively achieved during the first week of life with parenteral MgSO4. METHODS: Following informed-consent counselling, infants < 1500 gm BW and < 32 weeks GA were randomized to either LOW or HIGH Mg therapy. LOW Mg consisted of IV MgSO4 initially at 0.25 mEq/kg/d to maintain serum Mg levels ≤ 2.5 mEq/L. HIGH Mg consisted of IV MgSO4 initially at 1.0 mEq/kg/day to achieve serum Mg levels of 3.5-5.5 mEq/L during days 1-3 and 2.5-3.5 mEq/L during days 4-7. MgSO4 concentrations were adjusted according to babies' serum Mg levels. Infants were monitored closely for adverse effects of hypermagnesemia, including hypotension, oxygen destaturation, hypotonia, apnea, lethargy, decreased DTR's, cutaneous flushing, and hypocalcemia. RESULTS: 22 infants (11 per group) were enrolled into the trial. Median GA was 27 wks and median BW was 910 gms. Mean serum Mg levels (mEq/L) were:Table There were no instances of any adverse effects of hypermagnesemia, including no changes or differences in blood pressure at the higher serum Mg levels. CONCLUSION: Postnatal therapy with Mg is feasible and can be safely and effectively achieved.

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