May cause or aggravate elevated serum Ca levels in concomitant administration of Ca-containing drugs. Reduce dose of Al hydroxide as uraemic symptoms improve w/ therapy. Drugs that form sparingly soluble compd w/ Ca eg, tetracyclines, quinolones, drugs containing Fe, fluoride & estramustine should not be taken at the same time w/ Nephrotor to avoid disturbed absorption; take an interval of at least 2 hr. Increased risk of arrhythmia w/ cardioactive glycosides due to elevated serum Ca levels.