The short answer
Calcium can substantially reduce eltrombopag absorption. A high-calcium meal cut exposure by about 60% in a tablet study; in an oral-suspension study, taking eltrombopag 2 hours after a high-calcium meal still reduced exposure by about half. The label says to take eltrombopag without a meal or with one containing 50 mg calcium or less, and at least 2 hours before or 4 hours after calcium supplements, calcium antacids and calcium-rich foods. Typical calcium supplements contain 500 mg to 600 mg per dose.
What this answer covers
Calcium from supplements (carbonate, citrate and other salts), calcium-based antacids, and calcium-rich foods and drinks, with eltrombopag tablets or oral suspension.
- Supplement or preparation
- calcium
- Medication ingredient
- eltrombopag
What the studies measured
In 18 healthy men, a high-fat breakfast containing 427 mg calcium reduced eltrombopag AUC by 59% and peak concentration by 65%. In a second study of 26 adults, the tested low-calcium meals did not significantly change exposure despite differing fat content, supporting calcium as an important contributor. A later study with the oral suspension in 40 adults found a 75% reduction with a 448 mg calcium meal, 47% when the dose followed the meal by 2 hours and 20% when it preceded the meal by 2 hours.
What the label instructs
Take eltrombopag without a meal or with a meal containing no more than 50 mg calcium, and at least 2 hours before or 4 hours after calcium-rich foods, calcium supplements and antacids. The label reports the same reductions as the studies and attributes the food effect primarily to calcium. The ALVAIZ label carries identical wording.
Why supplement doses matter
Calcium supplements typically provide 500 mg or 600 mg per dose and calcium antacid chews about 270 mg to 400 mg, all far above the 50 mg limit the label sets for a meal. A multivitamin with 200 mg to 300 mg calcium also exceeds it. Treat every calcium-containing tablet, chew or fortified drink as something to separate from eltrombopag.
Spacing only partly protects
Even a 2 hour gap after a high-calcium meal left exposure about half of fasting, and a 2 hour gap before the meal still cost about 20%. That is why the label asks for 2 hours before or 4 hours after. One option is to take eltrombopag on an empty stomach at a fixed time and use calcium supplements later in the day, while maintaining the required gaps.
A later low-calcium meal study differed
A 2024 study in 96 healthy Chinese volunteers reported about 40% lower eltrombopag exposure with a high-fat, low-calcium meal, unlike the earlier low-calcium meal results. The abstract does not state the meal's calcium amount, so the reason for the difference is uncertain. The current label still permits dosing without a meal or with a meal containing 50 mg calcium or less; discuss a consistent routine with your pharmacist.
Evidence and practical considerations
Absorption & effectiveness
Calcium chelates eltrombopag in the gut; high-calcium meals reduced eltrombopag exposure by 59% to 75% in healthy volunteers, and the label limits calcium at the time of dosing to 50 mg and requires separation from calcium supplements, antacids and dairy.
- Exact scope
- Calcium from supplements, calcium-based antacids, dairy and calcium-fortified foods; tested as dietary calcium in meals. with Oral eltrombopag olamine tablets and oral suspension (PROMACTA and generics) and eltrombopag choline tablets (ALVAIZ). Both product labels give the same mineral-separation instruction; the products have different strengths and are not interchangeable dose for dose.
- Medication form and route
- oral medication; oral supplement
- Timing or duration
- Every eltrombopag dose while calcium products are used
What remains uncertain
- Pharmacokinetic studies in healthy adults after single doses; no calcium supplement tablet was tested; one food-effect study found a reduction with a low-calcium meal; no platelet-count outcome data.
Factors that may matter: Calcium dose; Timing relative to the eltrombopag dose; Fat and composition of the accompanying meal; Tablet versus oral suspension.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed eltrombopag
The label directs taking eltrombopag without a meal or with a meal containing 50 mg calcium or less, and at least 2 hours before or 4 hours after calcium-rich foods (over 50 mg calcium, such as dairy products, calcium-fortified juices and certain fruits and vegetables) or supplements containing calcium. A standard high-fat breakfast with 427 mg calcium reduced AUC by about 59% and peak concentration by 65%, and the label attributes the fall primarily to calcium because a low-calcium meal had no significant effect whatever its fat content. For the oral suspension, a meal with 448 mg calcium reduced AUC by 75% when taken together, 47% when the dose came 2 hours after the meal and 20% when it came 2 hours before.
How this applies: Exact eltrombopag (RxCUI 711942) in every marketed oral form; the label names iron, calcium, aluminum, magnesium, selenium and zinc by element and gives one spacing rule for all of them.
No calcium supplement tablet was tested; the calcium came from meals. Effects were measured in healthy adults after single doses.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed eltrombopag
The ALVAIZ label repeats the PROMACTA rule word for word: eltrombopag chelates polyvalent cations such as iron, calcium, aluminum, magnesium, selenium and zinc, and ALVAIZ is taken at least 2 hours before or 4 hours after antacids, dairy products and mineral supplements to avoid significant reduction in absorption.
How this applies: Confirms that the cation rule is unchanged for the newer eltrombopag choline product; it adds no element-specific data.
No new interaction study is reported for the choline salt; the wording is carried over from the innovator label.
Source 3: pharmacokinetic crossover study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Healthy adult volunteers (18 men in study A; 26 adults in study B).
The high-calcium breakfast reduced eltrombopag AUC by 59% (geometric mean ratio 0.41; 90% CI 0.36 to 0.46) and peak concentration by 65%. Low-calcium meals did not change exposure whatever their fat content (AUC ratios 0.87 to 1.03). The aluminum and magnesium antacid reduced AUC and peak concentration by about 70% (AUC ratio 0.30; 90% CI 0.24 to 0.36).
How this applies: Direct evidence of reduced eltrombopag exposure with a high-calcium meal. The low-calcium meal comparisons support calcium as an important contributor but do not establish an isolated effect for every food composition or a calcium supplement tablet.
Single doses in healthy volunteers read as an abstract; the antacid combined two cations plus sodium alginate, so the share of each is unknown; no mineral supplement product was tested.
Source 4: pharmacokinetic crossover study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Forty healthy adults aged 19 to 62.
AUC fell 75% when the suspension was taken with the high-calcium meal (ratio 0.25; 90% CI 0.224 to 0.287), 47% when taken 2 hours after the meal (ratio 0.53) and 20% when taken 2 hours before it (ratio 0.80). The suspension gave 22% higher AUC than the tablet.
How this applies: Direct evidence that calcium in food chelates eltrombopag and that a 2 hour gap only partly protects exposure; the label's Table 14 reports the same study.
Healthy volunteers, single doses, a dairy-based meal rather than a calcium supplement; abstract only.
Source 5: bioequivalence and food-effect study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Ninety-six healthy Chinese adults.
Test and reference tablets were bioequivalent fasting and fed; the high-fat, low-calcium meal reduced net systemic exposure by approximately 40%.
How this applies: Medication-only food effect; it does not involve a calcium supplement but shows that fat or meal composition can also lower exposure, so calcium is not the only food factor.
Bioequivalence study read as an abstract; the calcium content of the meal is not given in the abstract; a reduction with a low-calcium meal differs from the label's statement that low-calcium meals have no significant effect.
Source 6: federal supplement fact sheet
ods.od.nih.gov · Source check Sep 22, 2026
Population: General consumer population; no eltrombopag co-use data
Calcium supplements usually contain calcium carbonate or calcium citrate, commonly 500 mg or 600 mg of elemental calcium per dose (200 mg to 300 mg in multivitamin products); calcium carbonate is also the active ingredient of antacids such as Tums and Rolaids, providing about 270 mg to 400 mg calcium per chew. Listed medication interactions cover dolutegravir, levothyroxine, lithium and quinolones, not eltrombopag.
How this applies: Establishes typical supplement doses, which exceed the 50 mg calcium threshold in the eltrombopag label many times over, and that calcium antacids count as calcium products.
Consumer and professional summary; it does not mention eltrombopag.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Editorial update | |
| Editorial source audit clarified label scope, evidence limits and practical wording. No clinical approval was recorded. | |
| Research summary published | |
| Article prepared | |
| Prepared exact eltrombopag and Calcium article from inspected current labeling and original sources, with uncertainty stated. |
Article revision: 04cda562150a5f93
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
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