USP Results In
A Case Study Challenge

Coming in March,
look for the new Case Study Challenge Blog on U.S. Pharmacist's homepage. This dynamic special feature will present interactive polls and surveys, and, as always, we will post selected case study solutions that you submit!


Call for papers
USP Results In
What Would You Do?

Unchanging Lipid Levels

Click here for this case study, which was
emailed to you on February 14, 2013.

Author Answer

While AB is displeased with her current LDL level, she should be encouraged to continue good medication adherence and diet modification(s). She may also want to consider beginning a regular exercise routine.

The pharmacist may offer to discuss the patient’s current lipid therapy with her primary care provider. Statin therapy is often first line, as statins provide the greatest LDL reduction. Additionally, bile acid sequestrants, such as cholestyramine, are associated with many gastrointestinal side effects, including constipation, flatulence, and abdominal pain. Side effects often limit patient tolerability of therapy and adversely impact medication adherence. This patient’s frequent use of docusate sodium (five times a week) for constipation may be a result of her use of cholestyramine.

Furthermore, a drug interaction between levothyroxine and cholestyramine exists. Coadministration of cholestyramine and levothyroxine with breakfast results in a decreased concentration and efficacy of orally administered levothyroxine. As the pharmacist, it would be advisable to instruct the patient to take levothyroxine 1 hour prior to or 4 to 6 hours after cholestyramine.

Based on information the patient provided and symptoms described, the pharmacist may suspect that the patient’s thyroid-stimulating hormone level is high, and the patient is experiencing symptoms (tiredness, coldness, weight gain, and potentially constipation) of hypothyroidism. The change in dosing time of levothyroxine or change in lipid therapy will likely alleviate the symptoms.

Marissa C. Salvo, PharmD
Assistant Clinical Professor
University of Connecticut School of Pharmacy
Storrs, Connecticut

Reader Response

Explain to AB her hypothyroid symptoms of weight gain, fatigue, constipation, and "freezing" are occurring because of a drug interaction between cholestyramine and levothyroxine. The cholestyramine is binding to and decreasing the levothyroxine serum concentration. Counsel AB that levothyroxine 50 mcg should have been taken 1 hour before cholestyramine or 4 to 6 hours after. AB’s constipation is also being exacerbated by the cholestyramine. Recommend contacting AB's doctor in the meantime to modify her cholesterol medication to a more potent LDL-lowering alternative such as a statin since her LDL cholesterol has only been reduced approximately 8% with cholestyramine.

L. Balsamini, PharmD, BCPS

Basking Ridge, New Jersey

Reader Response

There appear to be two issues controlling cholesterol and hypothyroidism.
I would first recommend taking the thyroid medication on an empty stomach 1 hour prior to the cholestyramine with breakfast. If symptoms do not improve within a month have dose re-evaluated. I would also suggest doubling the dose of cholestyramine to 8 g bid and increase dietary fiber intake. If after 6 to 8 weeks cholesterol is not within acceptable limits, or constipation continues to be an issue, it may be necessary to change therapy to something like a statin.

N. Hart, PharmD
Auburn, Indiana

Reader Response

I would counsel AB to separate the cholestyramine from the levothyroxine. I believe that the cholestyramine is absorbing the levothyroxine, which would lead to the symptoms of lower energy and feeling cold. It would also be worthwhile to call the doctor and suggest a statin instead of the cholestyramine. One of the reasons that cholestyramine lost favor as a cholesterol-lowering drug was the side effect of constipation.

C. Sawyer, RPh

Reader Response

AB is taking cholestyramine, which is a bile sequestrant, at the same time with levothyroxine. This combination will decrease the effect of levothyroxine, which leads to the symptoms of hypothyroidism. AB should take levothyroxine 1 hour before or 4 to 6 hours after cholestyramine.

S. Yousfi, RPh