Monograph: |
Magnesium Oxide
Some pharmacopoeias include a single monograph which per-
mits both the light and heavy varieties while some have 2 sep-
arate monographs for the I varieties.
Heavy Magnesium Oxide (Ph. Eur.) and Light Magnesium
Oxide (Ph. Eur.) (Light Magnesia) an fine white powders and
are practically insoluble in water yielding solutions that are
alkaline to phenolphthalein. Both heavy and light magnesium
oxide dissolve in dilute acids with at most slight efferves-
cence. For the heavy variety 15 g occupies a volume of about
30 mL and for the light variety 15 g occupies a volume of
about 150 mL.
Magnesium Oxide (USP 23) is either the heavy or light vari-
ety. Heavy magnesium oxide is a relatively dense white pow-
der with 5 g occupying a volume of about 10 to 20 mL. Light
magnesium oxide is a very bulky white powder with 5 g oc-
cupying a volume of about 40 to 50 mL. Both varieties are
practically insoluble in water and alcohol but soluble in dilute
acids. Store in airtight containers.
Magnesium oxide is an antacid with general properties simi-
lar to those of magnesium hydroxide . It is given in
doses of up to about 800 mg by mouth. It is often given in
conjunction with aluminium-containing antacids such as alu-
minium hydroxide which counteract its laxative effect.
Magnesium oxide has been employed for its laxative proper-
ties in bowel preparation: doses of 3.5 g by mouth are given
for this purpose, combined with bisacodyl or sodium picosul-
phate.
Magnesium oxide is also used as a magnesium supplement in
deficiency states, and as a food additive.
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