Antacida og fruktjuice
Fråga: Why should one not drink fruit juice with antacida treatment?
Svar: Food drug interactions can be associated with alterations in the pharmacokinetic and pharmacodynamic profile of various drugs that may have clinical implications (1). Absorption and metabolism are the phases where food has the greatest effect.
Gastrointestinal absorption of aluminium in antacids containing Al (OH)3 is generally considered to be low, and that accumulation of this element in tissues is released by renal elimination(2). However, complex formation between aluminium and dietary citrate, as well as the decrease in gastric pH, may facilitate absorption of aluminium and increase the risk of toxic effects (2).
In one study, ten healthy men ingested, twice daily between meals, during each of the seven day experimental periods either citric acid ( in the form of lemon juice, equivalent to 6mg of citric acid), Al (OH)3 or both. Each experimental period was followed by a wash out, where the subjects kept normal diets (2). The concentrations of aluminium in the blood increased five fold after ingestion of both Al(OH)3 and citrate.
In a second study, the gastrointestinal absorption of aluminium from single doses of aluminium containing antacids were observed (3). The antacid tablets (containing 244mg of aluminium per tablet) were chewed and swallowed with either water, orange juice or citric acid solution. The citric acid (70g in 1000ml of distilled water), the orange juice, and tap water had a pH of 1.79, 3.41, and 6.5 respectively. The citric acid content of the orange juice was approximately 7 g L-1. The absorption of aluminium when the antacid/citric acid and antacid/orange juice combinations were taken, was fifty and eight times higher respectively, than when the antacid was ingested with water.
Medical information from two pharmaceutical manufacturers of aluminium containing antacid preparations (Alpharma - Link® and Ferring - Gaviscon®), quoted that the absorption of aluminium from these preparations is increased if combined with dietary citrates.
CONCLUSION
The absorption of aluminium is increased from aluminium containing antacids by concomitant ingestion of dietary citric acid. Antacids should be taken with water, and not with citrate containing fluids.
In patients with impaired renal function, absorbed aluminium may accumulate to toxic concentrations in bone and brain causing damage (3). This is particularly important for elderly patients, and the lowest effective dose should also therefore be recommended in this subgroup. The clinical implication of aluminium absorption in patients with normal renal function is unknown.
- 1. Singh BN. Effects of food on clinical pharmacokinetics. Clin Pharmacokinet 1999;37(3):213-255.
- 2. Slanina P, et al. Dietary Citric Acid Enhances Absorption of Aluminium in Antacids. Clin Chem 1986;32/3:539-541.
- 3. Weberg R, et al. Gastrointestinal absorption of aluminium from single doses of aluminium containing antacids in man. Eur J of Clin Invest 1986;16:428-432.