Module 2: Antacids Flashcards
What are antacids indicated for?
Heartburn assoc with mild GERD. Given effectiveness of PPI’s not used in tx for PUD.
Antacids usually contain a combination of?
A combination of: magnesium hydroxide, aluminum hydroxide, or calcium carbonate.
What is the treatment goal with antacids?
Relief of gastric pain and irritation.
What is the MOA for antacids?
Aluminum hydroxide binds growth factors and enhances their binding to experimental ulcers = possibly deliver growth factors to injured mucosa.
Promote angiogenesis in injured mucosa
Bine bile acids and also inhibit peptic activity.
Heavy metals are known to suppress but not eradicate H. Pylori.
What are the pharmacokinetic considerations of antacids?
A: With routine use, are nonabsorbable. With chronic use, 15-30% of magnesium and smaller amounts of aluminum may be absorbed.
D: Small amounts absorbed are widely distributed, cross the placenta, and appear in breast milk. Aluminum concentrates in the CNS.
M: N/A
E: Excreted by kidneys
What are special prescribing considerations for antacids?
Avoid peds but generally safe for all populations if taken as prescribed. Caution in renal and heart disease and chronic use in pregnancy and lactation.
What are factors that contribute to adverse effects of antacids?
The quantity and duration of therapy.
What are adverse effects associated with magnesium-containing antacids?
Diarrhea and hypermagnesia - latter important in patients with renal insufficiency.
What are adverse effects of antacids containing sodium?
Volume overload in susceptible patients
What are adverse effects of calcium carbonate containing antacids?
Ingestion of large amounts of calcium and absorbable alkali can lead to hypercalcemia, alkalosis and acute or chronic renal injury = a constellation known as the milk-alkali-syndrome.
What are adverse effects of aluminum hydroxide containing antacids?
Significant aluminum retention only occurs in renal failure and may result in neurotoxicity and anemia following prolonged tx.
Aluminum hydroxide blocks intestinal absorption of phosphate; 2 weeks of therapy with moderate doses can result in significant hypophosphatemia - esp. if pt has a low phosphate diet or is phosphate depleted for other reasons.
How do drug interactions with antacids occur?
Secondary to changes in GI motility and alterations in gastric and urinary pH. Impacts quinolone, NSAID and cephalosporin classes of drugs.
Notable interactions with tetracycline, quinidine, ketoconazole and oral glucocorticoids.
What are contraindications to antacids?
Severe abd pain of uknown cause
Renal failure (CrCl<30ml/min)
Tartrazine (synthetic dye) sensitivity
What should cautioned in taking antacids?
Antacids containing Mg in patients with renal insufficiency
Decreased bowel motility
Dehydration
Upper GI bleed
Children (<12 years) safety not established
What are monitoring parameters with antacids?
Serum phosphate, potassium, and calcium levels periodically during chronic use.
May cause increase serum Ca and decreased serum phosphate concentrations
What is the onset and duration for antacids?
Onset of action: as soon as 5 mins to relieve heartburn
If taken on empty stomach = duration 20-60 mins
If taken 1-3 hour after food = duration up to 4 hours
NOTE: advise pt to take 1-3 hours after meals and before bed for best results.
What are three common antacids?
Aluminum hydroxide, magnesium hydroxide and calcium carbinate
