➢ Antacids: weak bases that react with hydrochloric acid to form salt & water.
o Used in the treatment of Hyperacidity, GERD, PUD, hyperphosphatemia, and calcium
deficiency
o Contain combinations of
▪ metallic cation (aluminum, calcium, magnesium, and sodium)
▪ and basic anion (hydroxide, bicarbonate, carbonate, citrate, and trisilicate)
➢ Pharmacodynamics, Pharmacokinetics, Pharmacotherapeutics
o Neutralize Gastric Acidity (causes ^pH of the stomach and duodenal bulb)
o Inhibit proteolytic activity of pepsin
o Increase lower esophageal sphincter tone
o Acid-neutralizing capacity ANC varies between products expressed in mEqs
o If ingested in a fasting state, antacids reduce acidity for approximately 20 to 40 minutes
o If taken 1 hr after a meal, acidity is reduced for 2 to 3 hrs
o A second dose taken after a meal maintains reduced acidity for more than 4 hrs after the
meal
o The action of antacids occurs locally in the GI tract with minimal absorption, minimal
metabolism
o ALL antacids are contraindicated in the presence of severe abdominal pain of
unknown cause, especially if accompanied by fever
-HIGH SODIUM content: pts w/ HTN, CHF, marked renal failure, or on low-sodium diets
need to use low sodium preparation
-Concurrent administration with enteric-coated drugs, destroys the coating= alters
absorption, ^ the risk for adverse effects
-Administrations should be separated by at least 2 hours to decrease drug/drug interactions
1. Calcium based antacids: TUMS, Caltrate, Calcarb
• Prescribed to treat calcium deficient states, i.e. chronic renal failure, post-menopause,
and osteoporosis
• Used to bind phosphates in CRF
• Require Vitamin D for absorption from the GI tract
• Excreted mainly in feces, 20% in urine
• ADR: Contraindicated in the presence of hypercalcemia and renal calculi
• Can cause constipation- increase bulk, fluids and mobility, stool softener
• Administered 30min- 1hr on empty stomach or 3hr after meals
• Should not be administered with food containing large amounts of oxalic acid
(spinach, rhubarb), or phytic acid (bran, cereals), they decrease the absorption
of calcium
• Taking w/ foods containing phosphorus (milk, dairy) can lead to milk-alkali
syndrome (N/V, confusion, headache).
• Taking with acidic fruit juice improve absorption
, 2. Aluminum based: AlternaGEL, Amphojel, Mylanta
• Inhibit smooth muscle contraction and slow gastric emptying
• Used to bind phosphates in CRF
Aluminum
is not easily • Not absorbable with routine use
removed • Aluminum concentrated in the CNS
by dialysis • Bind with phosphate and excreted in feces
b/c it is • Prolonged use in patients with renal failure may result in dialysis osteomalacia
bound to o Aluminum deposits in bone and osteomalacia occurs
albumin & • Elevated aluminum tissue levels contribute to the development of dialysis
transferrin encephalopathy
= do not • Used to treat hyperphosphatemia in pts w/ renal failure & phosphate renal stone
cross prevention
dialysis • Can cause constipation- increase bulk, fluids and mobility, stool softener
membrane
, 3. Magnesium based: Milk of mag, Maalox, Mylanta
• Can be used to treat magnesium deficiencies from malnutrition, alcoholism, or mag-
depleting drugs
• Contraindicated in patients with renal failure & used with caution in pts with renal
insufficiency
The
malfuncti • Not absorbable with routine use
oning
kidney • Excreted in the urine
cannot • Contraindicated in patients with renal failure, use with caution for patients
excrete with any degree of renal insufficiency
magnesiu o Malfunctioning kidney is unable to excrete magnesium and hypermagnesemia
m= may result
hypermag • Can cause diarrhea- increase fiber intake (Alkalosis may occur in renal impairment)
nesemia Clinical Use and Dosing
,