Drug Interactions between Depen Titratabs and Precare

ADJUST DOSING INTERVAL: Food may interfere with the gastrointestinal absorption of penicillamine. In a study of six healthy volunteers, administration of penicillamine (500 mg) following a standard breakfast reduced the mean peak plasma concentrations of penicillamine by 48% compared to administration in the fasting state.

MANAGEMENT: Penicillamine should be administered on an empty stomach, at least one hour before or two hours after meals, and at least one hour apart from any other drug, food, or milk. This permits maximum absorption and reduces the likelihood of inactivation by metal binding in the gastrointestinal tract.

Switch to consumer interaction data

ADJUST DOSING INTERVAL: Concomitant use of some oral medications may reduce the bioavailability of orally administered iron, and vice versa.

Food taken in conjunction with oral iron supplements may reduce the bioavailability of the iron. However, in many patients intolerable gastrointestinal side effects occur necessitating administration with food.

MANAGEMENT: Ideally, iron products should be taken on an empty stomach (i.e., at least 1 hour before or 2 hours after meals), but if this is not possible, administer with meals and monitor the patient more closely for a subtherapeutic effect. Some studies suggest administration of iron with ascorbic acid may enhance bioavailability. In addition, administration of oral iron products and some oral medications should be separated whenever the bioavailability of either agent may be decreased. Consult the product labeling for specific separation times and monitor clinical responses as appropriate.

Switch to consumer interaction data

ADJUST DOSING INTERVAL: Oral administration of aluminum, copper, iron, zinc, magnesium, and possibly other minerals such as calcium may decrease the gastrointestinal absorption of penicillamine, and vice versa. The proposed mechanism involves chelation of penicillamine to polyvalent cations, which leads to formation of a nonabsorbable complex. In a study of six healthy volunteers, administration of penicillamine (500 mg) following a single dose of ferrous sulfate (300 mg) or antacid (Maalox Plus 30 mL) reduced the mean peak plasma concentration of penicillamine by 65% and 34%, respectively, compared to administration in the fasting state. In addition to chelation, some investigators suggest that antacids may also reduce penicillamine bioavailability by increasing gastric pH, which favors the oxidation of penicillamine to its poorly absorbed disulfide form. These changes could result in diminished therapeutic effects of penicillamine.

MANAGEMENT: Mineral supplements or other products containing polyvalent cations (e.g., antacids or preparations containing antacids such as didanosine buffered tablets or pediatric oral solution) should be administered at least two hours before or two hours after the penicillamine dose. In addition, pharmacologic response to penicillamine should be monitored more closely whenever these products are added to or withdrawn from therapy, and the penicillamine dosage adjusted as necessary. When penicillamine is coadministered with Suprep Bowel Prep (magnesium/potassium/sodium sulfates), the manufacturer recommends administering penicillamine at least 2 hours before and not less than 6 hours after Suprep Bowel Prep to avoid chelation with magnesium.

Switch to consumer interaction data