Peptica-C Drug Interactions

Acetaminophen: The time to attain maximum acetaminophen concentration is significantly delayed by the administration of antacid but the mean plasma peak and maximum plasma concentration of acetaminophen is not affected. Concurrent administration of acetaminophen and antacid also did not alter the elimination half-life of acetaminophen. The delayed absorption of acetaminophen does not have significance in a clinical setting.
Alendronate: Alendronate, a biphosphate, has a high affinity for many multivalent cations. Many antacids contain calcium, magnesium, or aluminum. These cations by binding with alendronate reduce gastrointestinal absorption of alendronate (Prod Info Fosamax, 2003). It is recommended that calcium, magnesium, or aluminum-containing antacids be administered at least one-half hour after alendronate. Patients using alendronate should wait at least one half-hour after taking alendronate before consuming antacids containing calcium, aluminum, or magnesium.
Calcitriol: Summary: The concomitant administration of calcitriol and magnesium-containing antacids may lead to the development of hypermagnesemia (Prod Info Calcijex, 2001). Concurrent administration of calcitriol and antacids containing magnesium is not recommended. If concomitant use cannot be avoided, monitor patient for magnesium intoxication (lethargy, weakness, hyporeflexia, and hypertension).
Digoxin: Simultaneous administration of digoxin and antacids that contain aluminum hydroxide, magnesium hydroxide, and magnesium trisilicate significantly decreased digoxin absorption when digoxin was administered as a tablet (Lanoxin, 2001). No alteration in digoxin absorption was observed following co-administration with calcium carbonate containing antacids. The mechanism responsible for altered digoxin absorption by antacids has not been identified (Brown et al, 1980; D'Arcy & McElnay, 1987). Digoxin serum levels should be monitored if a patient is receiving digoxin and antacids concurrently. The possible sequelae of a drug interaction may be avoided by separating the dosing interval of digoxin and antacids by approximately two hours. The use of digoxin capsules may reduce the interaction but more studies are required to substantiate this possibility.
Ephedrine: The renal elimination of ephedrine and pseudoephedrine are urinary pH dependent. By increasing the urinary pH above 7.5 the renal elimination of either drug may decrease by more than 50%. If the urine remains alkaline for more than 1 to 2 days increased ephedrine toxicity may be observed (Brater et al, 1980; Kuntzman et al, 1971). Monitor for possible ephedrine toxicity (eg, hypertension and tachycardia) and decrease the dose as needed. Patients on ephedrine who frequently require a urinary alkalinizer may need the dose of both drugs to be decreased.
Glipizide: The concomitant use of glipizide or glyburide with magnesium hydroxide antacids has been reported to increase the AUC of either drug (ie, the non-micronized form of these drugs: Diabeta, Micronase) (Neuvonen & Kivisto, 1991; Kivisto & Neuvonen, 1991; Boateng et al, 1991). Concurrent administration of glipizide and antacids is not recommended. If concurrent use cannot be avoided, monitor blood glucose for signs of hypoglycemia upon initiation of antacids. Reduce dose of glipizide as needed on the basis of serum blood glucose concentrations.
Ibuprofen: Summary: Concomitant administration of antacids (oral Maalox 400 mg) and ibuprofen was reported to result in no alterations in the pharmacokinetics of ibuprofen (Gontarz et al, 1987; Prod Info Motrin, 1999).
Mefenamic Acid: Summary: When magnesium hydroxide antacids are given with mefenamic acid and tolfenamic acid an increase in the peak concentration and decrease in the time to peak occurs for these agents. Aluminum hydroxide antacids, however, may lower the peak concentration of tolfenamic acid. Although the peak concentration of the NSAIDs may be lowered, their therapeutic effect is not (Neuvonen & Kivisto, 1988). Concurrent administration of mefenamic acid and antacids, especially those containing magnesium hydroxide or sodium bicarbonate, is not recommended. If concurrent use cannot be avoided, monitor for possible NSAID toxicity (eg, nausea, vomiting, or CNS depression) and adjust the doses accordingly.