Risk of pathological increases of the serum Ca level or intensification w/ medicaments containing Ca. Reduction of serum phosphate. A possible administration of Al hydroxide should be reduced when uremic symptoms improve under Renoket. Drugs that form sparingly soluble compd w/ Ca eg, tetracyclines, quinolones (eg, norfloxacin & ciprofloxacin), Fe-, fluoride- & estramustin-containing drugs (in order not to interfere w/ absorption, do not take Renoket w/ these drugs; 2 hr interval must be observed between intake of Renoket & drugs from the mentioned categories). Susceptibility towards heart/cardiac active-glycosides & hence, also the risk of arrhythmia increases w/ the rise of blood Ca conc.