Annette (Gbemudu) Ogbru, PharmD, MBA
Dr. Gbemudu received her B.S. in Biochemistry from Nova Southeastern University, her PharmD degree from University of Maryland, and MBA degree from University of Baltimore. She completed a one year post-doctoral fellowship with Rutgers University and Bristol Myers Squibb.
In this Article
- What are antacids, and how do they work?
- For what conditions are antacids used?
- Are there any differences among the different types of antacids?
- What are the warnings and precautions for antacids?
- What are the side effects of antacids?
- With which drugs do antacids interact?
- What antacids are available?
What are the side effects of antacids?
- Antacids may cause dose-dependent rebound hyperacidity and milk-alkali syndrome.
- Antacids that contain aluminum hydroxide may cause constipation, aluminum-intoxication, osteomalacia, and hypophosphatemia.
- Antacids that contain magnesium have a laxative effect that may cause diarrhea, and in patients with renal failure they may cause increased magnesium levels in the blood, because of the reduced ability of the kidneys to eliminate magnesium from the body in the urine.
With which drugs do antacids interact?
When antacids are taken with acidic drugs (for example, digoxin [Digitek], phenytoin [Dilantin], chlorpromazine [Thorazine], [isoniazid]), they cause the absorption of the acidic drugs to be decreased, which causes low blood concentrations of the drugs, which ultimately results in reduced effects of the drugs.
Antacids taken with drugs such as pseudoephedrine (Sudafed, Semprex D, Clarinex-D 12hr, Clarinex-D 24hr, , Deconsal, Entex PSE, Claritin D, and more), and levodopa (Dopar), increase absorption of the drugs and can cause toxicity/adverse events due to increased blood levels of the drugs.
Antacids that contain magnesium trisilicate and magnesium hydroxide when taken with some other medications (such as tetracycline) will bind to the drugs, and reduce their absorption and effects.
Sodium bicarbonate has a strong effect on the acidity of the urine, and this can affect the elimination (excretion) of some drugs by the kidney. Thus, sodium bicarbonate inhibits the excretion of basic drugs such as quinidine (Quinidex, Quinidine Gluconate, Quinidine Sulfate, Quinidine Injection) and amphetamines, and increases the excretion of acidic drugs such as aspirin.
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