Phillips' milk of magnesia

Overdose

Symptoms of overdose include gastrointestinal irritation and watery diarrhoea. Magnesium poisoning may produce hypermagnesaemia, symptoms of which include nausea, vomiting, flushing, thirst, hypotension, drowsiness, confusion, loss of tendon reflexes, muscle weakness, respiratory depression, cardiac arrhythmias, coma and cardiac arrest.

Treatment

Treatment consists of the intravenous administration of calcium gluconate injection 10% in a dose of 10-20ml to counteract respiratory depression or heart block. If renal function is normal, adequate fluids should be given to assist removal of magnesium from the body. Dialysis may be necessary in patients with renal impairment or severe hypermagnesaemia.

Shelf life

36 months; after opening, 6 months.

Contraindications

Hypersensitivity to any of the ingredients.

Incompatibilities

None.

List of excipients

Sodium Hydrogen Carbonate EP, Oil of Peppermint EP, Glycerol EP, Sodium Saccharin EP, Purified Water EP.

Undesirable effects

Diarrhoea may occur which is dose related.

In patients with impaired renal function there may be sufficient accumulation of magnesium to produce toxic effects.

Preclinical safety data

Magnesium hydroxide has been used for many years and no further data are presented in this section.

Pharmacodynamic properties

Magnesium hydroxide is practically insoluble in water and solution is not effected until the hydroxide reacts with hydrochloric acid in the stomach to form magnesium chloride. Its neutralising action is almost equal to that of sodium bicarbonate. When the dose is in excess of that required to neutralise the acid the intragastric pH may reach pH 8 or 9. Acid rebound following magnesium hydroxide is clinically insignificant.

Magnesium hydroxide has an indirect cathartic effect resulting from water retention in the intestinal lumen.

Pharmacokinetic properties

Magnesium hydroxide exerts its antacid therapeutic effect rapidly within the gastro-intestinal tract following oral administration and this action is therefore independent of pharmacokinetic properties. Following oral administration, about one third to half the magnesium is absorbed very slowly from the small intestine. Magnesium salts are excreted mainly in the urine with small amounts in the faeces and saliva.

Date of revision of the text

9th July 2013

Marketing authorisation holder

Omega Pharma Ltd.

1st Floor

32 Vauxhall Bridge Road

LONDON, SW1V 2SA

United Kingdom

Special precautions for storage

Store below 25°C. Do not freeze.

Nature and contents of container

Blue HDPE bottles with white HDPE screw turn tamper evident inner cap and external click on dosing cap. Pack size 100ml and 200ml.

Marketing authorisation number(s)

PL 02855/0072

Fertility, pregnancy and lactation

For Magnesium hydroxide no clinical data on exposed pregnancies are available.

Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/foetal development, parturition or postnatal development.

Magnesium crosses the placenta and is excreted in small amounts in breast milk. Use during pregnancy and lactation should be avoided unless on the advice of a doctor.

Special warnings and precautions for use

Adequate fluid intake should be maintained during use. If diarrhoea occurs especially in children or the elderly, discontinue use immediately. In case of renal impairment a doctor should be consulted as hypermagnesaemia may occur. If symptoms persist or worsen, a doctor or pharmacist should be consulted.

Do not use as a laxative for more than three consecutive days, or as an antacid for more than fourteen consecutive days.

If a laxative dose is needed every day or if there is a persistent abdominal pain further medical advice should be sought.

Users taking medicines either physician prescribed or self-prescribed should consult a doctor or pharmacist before use.

Keep out of the reach and sight of children.

Effects on ability to drive and use machines

Magnesium hydroxide is unlikely to cause any effects on the ability to drive and use machines.

Special precautions for disposal and other handling

Shake bottle well before use. Use within 6 months of opening.

Date of first authorisation/renewal of the authorisation

22nd March 1999

Interaction with other medicinal products and other forms of interaction

Magnesium hydroxide may interfere locally with the absorption of other drugs taken orally by increasing gastric pH. This can be avoided by giving other drugs 2-3 hours before the administration of magnesium hydroxide on the advice of a doctor.

Milk of Magnesia may interact with tetracycline, digoxin, dicoumerol and cimetidine. Magnesium hydroxide may increase the absorption of ibuprofen and decrease the absorption of penicallamine, bisphosphates, ketoconazole and tetracycline.

The excretion of salicylates will be increased by changes in urinary pH.

Co-administration of sodium polystyrene sulphonate results in a relative excess of bicarbonate ions, which are absorbed, and may lead to metabolic alkylosis.