Ezetimibe Interactions With Other Medicines
Ezetimibe is often prescribed alongside a statin, or on its own when statins are not tolerated. It has a reputation as a "clean" drug with few interactions, and that reputation is largely deserved. There are, however, a handful of combinations where timing, monitoring or caution really matter. Our editors summarise them.
How ezetimibe works and why interactions are few
Ezetimibe blocks a protein called NPC1L1 in the wall of the small intestine. This protein transports cholesterol from food and bile into intestinal cells. By blocking it, ezetimibe reduces cholesterol absorption, which leads the liver to take up more LDL from the blood.
After absorption, ezetimibe is rapidly converted in the gut wall and liver into a glucuronide, which is also active. Both forms circulate through the liver and intestine repeatedly, giving a long half-life. Importantly, ezetimibe is not significantly metabolised by the cytochrome P450 enzymes responsible for many drug interactions.
A detailed review of its pharmacology by Kosoglou and colleagues concluded that ezetimibe has no clinically meaningful interactions with many commonly used drugs, including most statins, antacids, oral contraceptives, digoxin and glipizide.
In the UK, ezetimibe is prescription-only and is recommended by NICE (technology appraisal TA385) as an option for primary hypercholesterolaemia when a statin is unsuitable or insufficient. The IMPROVE-IT trial showed that adding it to simvastatin after acute coronary syndrome produced a modest further reduction in cardiovascular events.
Bile acid sequestrants: a timing issue
Bile acid sequestrants such as colestyramine, colestipol and colesevelam bind bile acids in the gut. They also bind ezetimibe, reducing its absorption considerably when the two are taken together.
The official product information recommends taking ezetimibe at least two hours before or at least four hours after a bile acid sequestrant. This simple timing rule allows both medicines to work.
Bile acid sequestrants also bind fat-soluble vitamins and several other drugs, including levothyroxine and warfarin. People taking a sequestrant often need a written timetable to keep all their medicines properly spaced.
A pharmacist can help create a daily schedule. Many community pharmacies in England offer the New Medicine Service or structured medication reviews, which are ideal for sorting out such timing issues.
Ciclosporin, fibrates and warfarin
Ciclosporin, used after organ transplantation and for some autoimmune conditions, increases ezetimibe levels. Bergman and colleagues studied renal transplant patients and found substantially higher ezetimibe exposure. Ezetimibe can also slightly increase ciclosporin levels. Ciclosporin concentrations should be monitored closely when ezetimibe is started or stopped.
Fibrates may increase cholesterol excretion into bile and could therefore raise the risk of gallstones. Ezetimibe has been studied with fenofibrate, and the combination is used in practice. The product information advises caution, and gallbladder symptoms should be investigated. Combining ezetimibe with other fibrates has not been well studied.
Warfarin is a more variable story. Formal studies did not find a meaningful effect of ezetimibe on warfarin's anticoagulant activity, but post-marketing reports have described rises in INR. The product information recommends monitoring INR when ezetimibe is added to warfarin or fluindione.
| Medicine | Nature of interaction | Usual approach |
|---|---|---|
| Colestyramine, colestipol, colesevelam | Reduced ezetimibe absorption | Separate: ≥2 h before or ≥4 h after |
| Ciclosporin | Increased levels of both drugs | Monitor ciclosporin levels |
| Fenofibrate | Possible gallstone risk | Use with caution, report symptoms |
| Other fibrates | Not well studied | Generally avoided |
| Warfarin | Reports of raised INR | Check INR when starting |
| Statins | No major pharmacokinetic interaction | Monitor for muscle symptoms |
Ezetimibe with statins
Ezetimibe is most often taken with a statin, either as separate tablets or as a fixed-dose combination. Pharmacokinetic studies show no clinically important interaction between ezetimibe and atorvastatin, simvastatin, rosuvastatin or pravastatin.
The combination is attractive because the two drugs work in complementary ways: the statin reduces cholesterol production in the liver, while ezetimibe reduces cholesterol absorption from the gut. Adding ezetimibe to a statin typically lowers LDL by roughly another fifth or so beyond the statin alone.
Rare reports of muscle pain, raised creatine kinase and liver enzyme changes exist with the combination. The 2019 ESC/EAS guidelines nonetheless regard it as a well-tolerated step when targets are not reached on maximum tolerated statin therapy.
Any interaction that affects the statin, for example with clarithromycin or certain antifungals, still applies when the statin is taken together with ezetimibe. In such cases it is the statin, not ezetimibe, that drives the risk.
Supplements, food and everyday life
Ezetimibe can be taken with or without food, at any time of day. Grapefruit juice, which matters for some statins, does not affect ezetimibe itself.
Several supplements also act on cholesterol absorption or lipids:
- plant sterols and stanols, which work in the gut in a similar area;
- psyllium and other soluble fibres, which bind bile acids;
- red yeast rice, which contains a statin-like compound and should not be combined casually with prescribed statins;
- fish oil, which mainly affects triglycerides.
None of these is known to cause a dangerous interaction with ezetimibe, but they can change your lipid results and should be mentioned to your clinician. Red yeast rice in particular can add hidden statin exposure.
For active people, ezetimibe is not on the WADA Prohibited List and does not impair exercise capacity. Any unexplained muscle weakness or dark urine, especially after starting a combination with a statin, should be reported promptly.
Conclusions of the editorial team
Ezetimibe has relatively few interactions because it bypasses the main cytochrome P450 pathways.
The most important practical points are spacing it from bile acid sequestrants, monitoring ciclosporin levels and INR in people on warfarin, and caution with fibrates.
When combined with statins it is generally safe and effective, but statin-related interactions still apply. Related topics on our site include atorvastatin clinical trials, preparing for an apolipoprotein B test, and myths about losartan.
References
- Kosoglou T, Statkevich P, Johnson-Levonas AO, et al. Ezetimibe: a review of its metabolism, pharmacokinetics and drug interactions. Clin Pharmacokinet. 2005;44(5):467–494.
- Cannon CP, Blazing MA, Giugliano RP, et al. Ezetimibe added to statin therapy after acute coronary syndromes. N Engl J Med. 2015;372(25):2387–2397.
- Bergman AJ, Burke J, Larson P, et al. Interaction of single-dose ezetimibe and steady-state cyclosporine in renal transplant patients. J Clin Pharmacol. 2006;46(3):328–336.
- Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Eur Heart J. 2020;41(1):111–188.
- National Institute for Health and Care Excellence. Ezetimibe for treating primary heterozygous-familial and non-familial hypercholesterolaemia. Technology appraisal guidance TA385. London: NICE; 2016.
