Conzace Drug Interactions

Vitamin A: Anticoagulant (e.g., warfarin): Concomitant administration with large doses of vitamin A may lead to increased risk of bleeding.
Retinoid (e.g., etretinate, isotretinoin, tretinoin): Avoid concomitant use of retinoids and preparations containing vitamin A or its derivatives because of the potential for additive undesirable effects.
Minocycline: Concomitant administration may lead to increased risk of pseudomotor cerebri.
Statins: Prolonged statin treatment may increase serum vitamin A levels.
Vitamin C: Antacids: Increased risk of aluminum toxicity has been noted with concomitant use; therefore, it is not recommended, especially in patients with renal insufficiency.
Aspirin: Concomitant intake may lead to increased urinary excretion of ascorbic acid and decreased excretion of aspirin.
Disulfiram: Prolonged administration of large doses (1 g daily) of vitamin C may interfere with the alcohol-disulfiram reaction.
Fluphenazine: Concomitant administration with ascorbic acid resulted in decreased fluphenazine plasma level.
Mexiletine: Large doses (1 g daily) of ascorbic acid may accelerate excretion of mexiletine.
Paracetamol: Ascorbic acid increases the apparent half-life of paracetamol.
Oral contraceptives (containing estrogens): These may reduce blood levels of ascorbic acid; large doses (> 1 g) of vitamin C may increase plasma estrogen levels (possibly converting low-dose oral contraceptive to high-dose oral contraceptive); possibly breakthrough bleeding associated with withdrawal of high-dose vitamin C.
Warfarin: Ascorbic acid has reportedly decreased the anticoagulant effect of warfarin.
Others: Acidification of the urine following ascorbic acid administration may result in altered excretion of other drugs.
Vitamin E: Anticoagulants: Vitamin E reportedly may have anti-vitamin K effects; concomitant intake of anticoagulants (e.g., warfarin) and vitamin E may result in hemorrhage (bleeding).
Antiplatelets: High doses of vitamin E may also potentiate the effects of antiplatelets (e.g., aspirin, clopidogrel, ticlopidine) and herbs with antithrombotic activity such as garlic and ginkgo.
Zinc: Antibiotics (cephalosporins, quinolones, tetracyclines): Zinc decreases the absorption of these antibiotics. Taking the antibiotic at least 2 hours before or 4 to 6 hours after taking zinc supplement minimizes this interaction.
Bisphosphonates (alendronate, etidronate, risedronate): Concomitant intake of a bisphosphonate and zinc may decrease the absorption of both the bisphosphonate and zinc.
Cholesterol medicines: Additive effects are possible with concomitant administration; use with caution.
Copper or iron: Concomitant administration with zinc inhibits the absorption of copper and iron. Administer zinc and copper or iron as far apart as possible.
Interference with Laboratory Tests: Vitamin C interferes with the results of the following laboratory tests: paracetamol, aspartate aminotransferase, bilirubin, carbamazepine, creatinine, glucose, lactate dehydrogenase, stool guaiac, theophylline, and uric acid.
Tell the doctor about other medicines the patient is taking including supplements and herbal products, and other caffeine-containing products.