Thiazide diuretics reduce the urinary excretion of calcium. Due to increased risk of hypercalcaemia, serum calcium should be regularly monitored during concomitant use of thiazide diuretics.
Concomitant use of phenytoin or barbiturates may reduce the effect of vitamin D3 since the metabolism increases.
Systemic corticosteroids reduce calcium absorption. During concomitant use, it may be necessary to increase the dose of Kalcipos-D.
Hypercalcaemia may increase the toxicity of cardiac glycosides during treatment with calcium and vitamin D. Patients should be monitored with regard to electrocardiogram (ECG) and serum calcium levels.
The efficacy of levothyroxine can be reduced by the concurrent use of calcium, due to decreased levothyroxine absorption. Administration of calcium and levothyroxine should be separated by at least four hours.
Calcium salts may decrease the absorption of iron, zinc and strontium ranelate. Consequently, iron, zinc or strontium ranelate preparations should be taken at least two hours before or after Kalcipos-D.
If a bisphosphonate is used concomitantly, this preparation should be administered at least one hour before the intake of Kalcipos-D since gastrointestinal absorption may be reduced.
Calcium may also reduce absorption of sodium fluoride and such preparations should be administered at least three hours before the intake of Kalcipos-D.
Simultaneous treatment with ion exchange resins such as cholestyramine or laxatives such as paraffin oil may reduce the gastrointestinal absorption of vitamin D.
Treatment with orlistat may potentially impair the absorption of fat-soluble vitamins (e.g. vitamin D3.
Calcium carbonate may interfere with the absorption of concomitantly administered tetracycline preparations. For this reason, tetracycline preparations should be administered at least two hours before or four to six hours after oral intake of calcium.
The absorption of quinolone antibiotics may be impaired if administered concomitantly with calcium. Quinolone antibiotics should be taken two hours before or six hours after intake of calcium.
Oxalic acid (found in spinach and rhubarb) and phytic acid (found in whole cereals) may inhibit calcium absorption through formation of insoluble compounds with calcium ions. The patient should not take calcium products within two hours of eating foods high in oxalic acid and phytic acid.