<p>Drug interactions: Interaction studies have not been conducted in patients on dialysis. In interaction studies in healthy volunteers, Sevelamer Hydrochloride, which contains the same active moiety as Sevelamer Carbonate, decreased the bioavailability of ciprofloxacin by approximately 50% when co-administered with Sevelamer Hydrochloride in a single dose study. Consequently, Sevelamer Carbonate should not be taken simultaneously with ciprofloxacin. Reduced levels of ciclosporin, mycophenolate mofetil and tacrolimus have been reported in transplant patients when co-administered with Sevelamer Hydrochloride without any clinical consequences (i.e graft rejection). The possibility of an interaction cannot be excluded and a close monitoring of blood concentrations of ciclosporin, mycophenolate mofetil and tacrolimus should be considered during the use of combination and after its withdrawal. Very rare cases of hypothyroidism have been reported in patients co-administered Sevelamer Hydrochloride, which contains the same active moiety as Sevelamer Carbonate, and levothyroxine. Closer monitoring of thyroid stimulating hormone (TSH) levels is therefore recommended in patients receiving Sevelamer Carbonate and levothyroxine. Patients taking anti-arrhythmic medicinal products for the control of arrhythmias and anti-seizure medicinal products for the control of seizure disorders were excluded from clinical trials. Caution should be exercised when prescribing Sevelamer Carbonate to patients also taking these medicinal products. In interaction studies in healthy volunteers, Sevelamer Hydrochloride, which contains the same active moiety as Sevelamer Carbonate, had no effect on the bioavailability of digoxin, warfarin, enalapril or metoprolol. Sevelamer Carbonate is not absorbed and may affect the bioavailability of other medicinal products. When administering any medicinal product where a reduction in the bioavailability could have a clinically significant effect on safety or efficacy, the medicinal product should be administered at least one hour before or three hours after Sevelamer Carbonate, or the physician should consider monitoring blood levels.</p>