Antacids

Question 1

Give the generic and brand names of example antacids

Answer 1

• 50mg sodium alginate, 133.5mg sodium bicarbonate and 80mg calcium carbonate per 5ml (Gaviscon)
• Sodium bicarbonate (Alka Seltzers, Eno)
• Calcium carbonate (Tums, Calcichew)
• Magnesium/Aluminum hydroxide (Maalox, Milk of Magnesium)

Question 2

Explain the method of action of antacids

Answer 2

• Weak bases
• React with HCl and neutralizes
• Gaviscon ↓ viscosity of gastric acid to forms a raft

Question 3

What are the indications for antacids?

Answer 3

• Gastro-oesophageal reflux

* Function (non-ulcer) dyspepsia

Question 4

What are the contraindications for antacids?

Answer 4

• Patients with salt-restricted diets – sodium bicarbonate
• Hepatic impairment (fluid retention) – avoid large amounts of Na, Mg and those that cause constipation
• Renal impairment (fluid retention) – avoid large amounts of Na and Al

Question 5

What are the side effects of antacids?

Answer 5

• Rebound acid secretions – calcium carbonate
• Hypercalcaemia
• Gastric distention/belching – Sodium bicarbonate
• Metabolic alkalosis in high doses – sodium bicarbonate
• Anaphylactic/hypersensitivity reaction
• Bronchospasm
• Ca/Al = constipation
• Mg/Na = diarrhoea

Question 6

What are the interactions with antacids?

Answer 6

• Impairs absorption of many drugs – leave 2 hours between other drugs e.g. ACE inhibitors, antibiotics, bisphosphonates, digoxin, levothyroxine, PPI’s
• Aspirin - ↑ alkalinity of urine so ↑ excretion
• Lithium - ↑ alkalinity of urine so ↑ excretion
• Any tablets that are enteric coated – antacids can damage these

Question 7

What organ eliminates antacids?

Answer 7

• Kidneys

Question 8

What patient information would you give for antacids?

Answer 8

• Take after meals AND at bedtime
• Should work within 20 mins
• Discuss lifestyle measures e.g. eating smaller meals more often, stop smoking, avoiding hot food