I was recently exhibiting at an ACOFP convention and a doctor asked me if you could take Effer-K (potassium citrate) with grapefruit juice? He was concerned because a drug interaction exists for administering certain statins with grapefruit juice.

http://cholesterol.about.com/od/statindrugs/a/grapefruitstat.htm

This article suggests that with some statins you need to aviod grapefruit, others wait a few hours and then you can consume.
Furthermore, according to Wikipedia (http://en.wikipedia.org/wiki/Statin):
“Consumption of grapefruit or grapefruit juice inhibits the metabolism of certain statins. Bitter oranges may have a similar effect. Furanocoumarins in grapefruit juice (i.e. bergamottin and dihydroxybergamottin) inhibit the cytochrome P450 enzyme CYP3A4, which is involved in the metabolism of most statins (however, it is a major inhibitor of only lovastatin, simvastatin, and to a lesser degree, atorvastatin) and some other medications 43] (flavonoids (i.e. naringin) were thought to be responsible).”

This is, however, controversial among the medical community.

Grapefruit juice contains a high amount of potassium citrate so the physician was concerned.

“Grapefruit contains a number of polyphenolic compounds, including the flavanone naringin, alongside the two furanocoumarins bergamottin and dihydroxybergamottin. These inhibit the drug-metabolizing enzyme isoform CYP3A4 predominately in the small intestine, but at higher doses also inhibit hepatic CYP3A4.[21] It is via inhibition of this enzyme that grapefruit increases the effects of a variety of drugs by increasing their bioavailability.[22][23][24][25][26][27] In particular grapefruit and bitter oranges are known to interact with statins.”

The mechanism of action for statins is different than Effer-K.