Another study, which included 1,014 primary care patients taking statins who had at least one transaminase measurement, only 1% (10) had a significant elevation and another 5 had moderate elevations, but none of those cases appeared to be related to statin use (Arch. Intern. Med. 2003;163:688–92).
Based on the data, it's reasonable to monitor liver function within the first 12 weeks of therapy and perhaps annually thereafter for the first 3–4 years. After that, if the patient has been on a stable dose and has not had an ALT elevation, it's not necessary to keep going. “I don't continue to monitor for years and years,” Dr. Paauw said.
And finally, there's the grapefruit juice problem. Grapefruit juice increases the bioavailability of drugs known to be metabolized by the CYP3A4 subunit of the P450 system, including simvastatin, lovastatin, and to a lesser degree, atorvastatin. Pravastatin, fluvastatin, and rosuvastatin do not rely on CYP3A4 and therefore do not interact with grapefruit juice.
Small amounts—a half of a grapefruit every 2 weeks, for example—are not likely to be clinically significant, but a daily glass of juice at breakfast may increase statin bioavailability.