3. Definition of Magma
-Two-phase system with large particle size or floccules
of small distance particles. These water insoluble
particles . Thick and viscous.
Commonly known as milk magnesia
Note : -Magma is semi-solid dosage form
-Route administration of magma : oral
4. (a) – It is prepared by simple hydration – sprinkling the parent
substance on hot purified water.
(b) Magnesia Magma – It is prepared by hydration of calcined magnesia or by
chemical reaction between sodium hydroxide and magnesium sulfate.
(c) Bismuth Magma – It is prepared by reacting bismuth nitrate with ammonium
carbonate not by the process of simple solution with mixing but by previously reacting
bismuth subnitrate with nitric acid and official ammonium carbonate with diluted
ammonia solution and then mixing the resulting two solutions.
5. (1) Bentonite Magma, USP
Other Name: Magma Bentoniti
Formula:
Bentonite 50g
Purified water, q.s. ________
To make 1000ml
Preparation:
To make 800ml of heated purified water, sprinkle upon it the bentonite, in portions allowing each
portion to become thoroughly wetted without stirring. Allow to stand with occasional stirring for 24
hours. Stir until a uniform magma is obtained. Add sufficient quantity of purified water to make
1000ml and mix.
It may also be prepared by mechanical means, such as by the use of a blender. Place about 500ml
of purified water in the blender, and while the machine is running, add the bentonite. Add purified
water to make up to 1000ml or up to the operating capacity of the blender. Blend the mixture for 5
to 10 minutes; add purified water to make 1000ml and mix.
6. METHOD OF PREPRATION
There are two methods of preparations:
(a) Hydration method
(b) Hydration and Precipitation method.
7. HYDRATION METHOD:
Light magnesium oxide (MgO) is hydrated
with water to produce magnesium hydroxide
[Mg (OH)2].
MgO + H2O ® Mg(OH)2.
This method is followed by industries and in
Milk of Magnesia.
8. Hydration and Precipitation
method:
A solution of sodium hydroxide (NaOH) is
triturated with light magnesium oxide to form
a smooth cream. It is diluted with water.
MgSO4 + 2NaOH = Mg(OH)2¯ + Na2CO3.
MgO + H2O = Mg(OH)2¯
Precipitation formed
The precipitation is mixed with chloroform
water to give the final preparation.
9. ADVERSE REACTIONS
The adverse effects of parenterally administered Magnesia
Magma usually are the result of Magnesia Magma intoxication.
These include flushing, sweating, hypotension, depressed
reflexes, flaccid paralysis, hypothermia, circulatory collapse,
cardiac and central nervous system depression proceeding to
respiratory paralysis.
Hypocalcemia with signs of tetany secondary to Magnesia
Magma sulfate therapy for eclampsia has been reported.
10. OVERDOSAGE
Magnesia Magma intoxication is manifested by a sharp drop
in blood pressure and respiratory paralysis. Disappearance of
the patellar reflex is a useful clinical sign to detect the onset
of Magnesia Magma intoxication. In the event of overdosage,
artificial ventilation must be provided until a calcium salt can
be injected intravenously to antagonize the effects of
Magnesia Magma.
11. For Treatment of Overdose
Artificial respiration is often required. Intravenous calcium, 10 to
20 mL of a 5% solution (diluted if desirable with isotonic sodium
chloride for injection) is used to counteract effects of
hypermagnesemia. Subcutaneous physostigmine, 0.5 to 1 mg
may be helpful.
Hypermagnesemia in the newborn may require resuscitation and
assisted ventilation via endotracheal intubation or intermittent
positive pressure ventilation as well as intravenous calcium.
