May 19, 2024

Magnesium Hydroxide mixture / Milk of magnesia

Magnesium Hydroxide mixture experiment preparation and evaluation, Milk of magnesia


Preparation and Evaluation of Magnesium Hydroxide mixture / Milk of magnesia

Glassware: Beaker, glass rod, mortar & pestle, glass bottle, etc.


IngredientsQty GivenActivity
Magnesium Sulphate Formation of Magnesium Hydroxide
Sodium Hydroxide 
Light Magnesium oxide 
Purified water freshly boiled and cooledq.s to 1000 mlVehicle


Time needed: 1 hour

How to prepare Magnesium Hydroxide mixture/ How to prepare Milk of magnesia

  1. Preparation of Sodium hydroxide

    Sodium hydroxide was dissolved in purified water.

  2. Preparation of smooth cream

    Light magnesium oxide was triturated with this solution to form a smooth cream.

  3. Mixing both solutions

    Pour this suspension into a thin stream into a solution of the magnesium sulfate in purified water, stirring continuously during the mixing.

  4. Set mixture aside

    The mixture is set aside in a closed container for 48 hrs

  5. Washing

    Allow the precipitate to subside, remove the clear liquid, and wash the precipitate with purified water until the washings give only a slight reaction for sulfate. Test with barium chloride solution. Mix the washed precipitate with purified water

  6. Make up the volume

    Add sufficient purified water to produce the required volume.


1. Chemical Properties:
Milk of Magnesia is composed of magnesium hydroxide (Mg(OH)₂), which is an inorganic compound. Magnesium hydroxide is a weak base that reacts with hydrochloric acid (HCl) in the stomach to form water and magnesium chloride (MgCl₂). This reaction helps neutralize excess stomach acid, providing relief from indigestion and heartburn.

2. Suspension Formation:
Milk of Magnesia is formulated as a suspension, which is a dispersion of solid magnesium hydroxide particles in a liquid vehicle. The choice of a liquid vehicle, such as water or a flavored solution, is important to ensure the suspension remains stable and easy to administer.

3. pH Adjustment:
The pH of Milk of Magnesia is adjusted to optimize its antacid properties. Magnesium hydroxide has maximum solubility and reactivity around pH 10.5. Formulators adjust the pH to ensure that the magnesium hydroxide particles remain well-dispersed and effective in neutralizing stomach acid.

4. Viscosity and Texture:
The viscosity of Milk of Magnesia is adjusted to achieve a desirable texture and mouthfeel. Thickeners or suspending agents may be added to prevent the settling of the solid particles and to ensure uniform distribution throughout the suspension.

5. Flavoring and Sweetening:
To improve patient acceptability, Milk of Magnesia is often flavored and sweetened. Flavoring agents, such as mint or fruit flavors, are added to mask the chalky taste of magnesium hydroxide. Sweeteners, such as sucrose or high fructose corn syrup, can enhance the overall palatability.

6. Stability and Settling:
Stability is a critical consideration in Milk of Magnesia formulation. Proper selection of suspending agents and thorough mixing help prevent the settling of the solid particles over time. Shake well instructions on the label remind users to homogenize the suspension before administration.

7. Dosage Forms:
Milk of Magnesia is available in different dosage forms, including liquid suspensions and chewable tablets. Chewable tablets are formulated to disintegrate in the stomach, releasing magnesium hydroxide for antacid action.

8. Laxative Action:
In addition to its antacid properties, Milk of Magnesia can act as a laxative. When ingested, magnesium hydroxide attracts water into the intestines, softening the stool and promoting bowel movements. This is particularly useful for relieving constipation.

9. Pharmacokinetics:
After ingestion, magnesium hydroxide dissociates into magnesium ions and hydroxide ions in the stomach. The magnesium ions may be partially absorbed in the intestines and can contribute to dietary magnesium intake. However, the laxative effect is primarily due to the osmotic action of unabsorbed magnesium ions.


Avoid giving it to patients with hypophosphatemia and impairment of renal function.

Do not co-administer with antidepressants and anti-epileptic drugs.


Milk of magnesia: It is an antacid that consists of a suspension of magnesium hydroxide in water. Milk-like appearance is giving the name of magnesia

Laxative: The agents which loosen stools and increase bowel movement.

Antacid: The agents or drugs which neutralize the excess secretion of hydrochloric acid

Preservative: The chemical substances used in various pharmaceutical dosage forms and cosmetic preparations to prevent or inhibit microbial growth.

Flavoring agent: The agents are usually added in pharmaceutical dosage form to give flavor to the pharmaceutical formulation.

Vehicle: Vehicles or solvents are the media in which ingredients of a formulation are Dissolved, suspended, or dispersed.


What are the Category, Container, Storage, and Labelling directions for Magnesium Hydroxide mixture/Milk of magnesia?

Category: Laxative (8-16 ml) and antacid (1-4 ml)

Container & storage: Well-closed container in a cool place

Labelling Direction: Shake well before use

A magnesium hydroxide mixture is also known as?
What is the other name of magnesium hydroxide?

Magnesium hydroxide mixture is also known as Milk of magnesia or magnesium(2+) hydroxide

What is Milk of Magnesia?

Milk of Magnesia is a white liquid suspension of magnesium hydroxide in water. It is commonly used as an antacid to neutralize excess stomach acid and as a laxative to relieve constipation.

What is the category of Milk of magnesia?

Laxative (8-16 ml) and antacid (1-4 ml)

How does Milk of Magnesia work as an antacid?

Milk of Magnesia works as an antacid by neutralizing stomach acid, which can help provide relief from heartburn, indigestion, and acid-related stomach discomfort.

How does Milk of Magnesia work as a laxative?

Milk of Magnesia works as a laxative by drawing water into the intestines, which softens the stool and promotes bowel movements. It is used to relieve temporary constipation.

Is Milk of Magnesia safe to use?

Milk of Magnesia is generally safe when used as directed. However, prolonged or excessive use can lead to electrolyte imbalances. It is important to follow dosing instructions and consult a healthcare professional if you have any concerns.

Can Milk of Magnesia be used by pregnant or breastfeeding women?

Pregnant and breastfeeding women should consult their healthcare provider before using Milk of Magnesia. While it is often considered safe, medical guidance is recommended.

How is Milk of Magnesia dosed?

Dosing instructions for Milk of Magnesia vary based on the specific product and the purpose for which it is being used (antacid or laxative). Always follow the dosing instructions on the product label or as directed by a healthcare professional.

Can Milk of Magnesia interact with other medications?

Milk of Magnesia can interact with certain medications, including antibiotics, heart medications, and tetracycline. It is important to inform your healthcare provider about all the medications you are taking before using Milk of Magnesia.

Are there any side effects of Milk of Magnesia?

Common side effects of Milk of Magnesia may include diarrhea, stomach cramps, and upset stomach. Serious side effects are rare but may include allergic reactions. Consult a healthcare professional if you experience any unusual or severe symptoms.

Can Milk of Magnesia be used for children?

Milk of Magnesia can be used for children under the guidance of a healthcare provider. The appropriate dosage will depend on the child’s age and weight.

Can Milk of Magnesia be used for long-term constipation?

Milk of Magnesia is generally not recommended for long-term or chronic constipation. Consult a healthcare provider if you experience persistent or recurring constipation.

Is Milk of Magnesia available in different formulations?

Yes, Milk of Magnesia is available in various formulations, including liquid suspensions and chewable tablets. Different formulations may have different dosing instructions.

How should Milk of Magnesia be stored?

Milk of Magnesia should be stored at room temperature, away from heat and moisture. Be sure to check the product label for specific storage instructions.

Can Milk of Magnesia be used for heartburn?

Yes, Milk of Magnesia can be used as an antacid to relieve heartburn and acid indigestion. It helps neutralize excess stomach acid.

Can Milk of Magnesia be used for upset stomachs?

Yes, Milk of Magnesia can be used to provide relief from an upset stomach caused by excess stomach acid.

Can Milk of Magnesia be used as a treatment for peptic ulcers?

Milk of Magnesia is not typically used as a primary treatment for peptic ulcers. It is important to consult a healthcare provider for appropriate ulcer treatment.

Milk of Magnesia is a versatile over-the-counter medication commonly used to address digestive issues such as heartburn, indigestion, and temporary constipation. However, it is important to use it as directed and consult a healthcare professional if you have any concerns or if your symptoms persist.

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