Iron-Whey-Protein Microspheres Could Improve Adherence to Oral Iron Therapy

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Results of the PRECISION trial suggest use of iron-whey-protein microspheres could aid in improving adherence to oral iron therapy as well as staving off adverse GI events.

The use of an iron-whey-protein formulation could improve adherence, tolerability, and symptoms of iron deficiency among women of childbearing age with intolerance to oral iron therapy, according to the results of the PRECISION trial.

A 2-part trial assessing 3 formulations of iron-whey-protein microspheres in women with a self-reported history of intolerance to oral iron, results indicate use was linked to significant improvement in adherence relative to prior oral iron therapy, as well as increased levels of ferritin, hemoglobin, and energy levels.

“Pharmacists and other healthcare professionals should be aware that undiagnosed iron deficiency and [anemia] are common in women of childbearing age with a history of intolerance to oral iron,” wrote investigators.1 “This study shows that IWP up to 50 mg daily is well tolerated in this population and that higher doses can improve iron stores and [hemoglobin] levels while reducing tiredness.”

As a result of its association with increased risk for adverse outcomes, anemia represents a significant public health issue across the world. According to the World Health Organization, the global prevalence of anemia is approximately 29.9%, with this figure increasing to 36.5% among pregnant women.2 A prospective, double-blind, parallel-group, clinical study conducted in Ireland, the current trial was launched with the intent of assessing the effects of iron-whey-protein microspheres at doses of 25 mg capsule twice daily (high dose), 25 mg in the morning with matching dummy capsule in the evening (standard dose), and 14 mg in the morning and matching dummy capsule in the evening (low dose).1

Funded by Solvotrin Therapeutics Limited, the Prospective Randomised Study of Women of Childbearing Age with Gastrointestinal Intolerance to Oral Iron (PRECISION) trial’s primary outcomes of interest were differences in adherence, gastrointestinal tolerability, ferritin, transferrin saturation and hemoglobin levels relative to their prior oral iron product and the iron-why-protein microspheres after 12 weeks. For inclusion in the trial, which was led by Mark Ledgwidge, PhD, adjunct professor at the University College Dublin and director of Solvotrin Therapeutics, participants were required to be non-pregnant women between 18-55 years of age, have a self-reported history of intolerance to oral iron, be without a current diagnosis of gastrointestinal disease, and to take an initial phone screen to confirm their demographics, medical history and history of gastrointestinal intolerance to oral iron.1

A total of 204 women were identified for screening. Investigators pointed out 62.7% of women screened had a ferritin level of less than 30 µg/L, 31.9% had moderate ferritin less than 12 µg/L, and 16.2% had iron deficiency anemia, which was defined as ferritin less than 30 µg/L and hemoglobin less than 12 g/dL. After exclusion of women without iron deficiency, the total cohort for randomization included 59 patients.1

At baseline, this cohort had a mean age of 35.2 (Standard deviation [SD], 11.0) years, median ferritin level of 9.0 (Interquartile range [IQR], 6.00-15.5), mean Hb of 12.3 (SD, 1.25) g/dL, and median serum iron of 9.60 (IQR, 5.75-16.3). Among the 59 patients included, 18, 21, and 20 were randomized to the low, standard, and high dose of arms of the trial.1

Upon analysis, results indicated 81.4% of the women included in the randomization portion of the trial were classified as adherent or persistent at the end of the 12-week treatment period. Investigators noted this was greater than the 20.3% rate of adherence or persistence with the prior oral iron therapy (Fisher’s Exact test, P < .001).1

Additionally, when assessing the incidence of gastrointestinal intolerance, fewer instances were observed with treatment than with the prior oral iron therapy (0.59 [SD, 0.91] vs 4.0 [SD, 2.2]; (Fisher’s Exact and T-test respectively, Both P < .001). Investigators also highlighted no differences in results were observed in assessments off adherence or tolerability across the different iron-whey-protein formulations and ferritin, hemoglobin and energy levels increased significantly by the end of the 12 weeks across all doses.1

Investigators called attention to limitations within their study to consider when interpreting results. These included, but were not limited to, not being powered a priori on other outcomes, reliance on self-reporting for gastrointestinal intolerance and adherence, and selection of a population based on a previous negative experience with oral iron therapy.

“Undiagnosed iron deficiency is common in women of childbearing age with a history of intolerance to oral iron and iron-whey-protein microspheres can improve adherence, [gastrointestinal] tolerability, iron stores, [hemoglobin] and energy levels in these women,” investigators concluded.1


  1. Ledwidge M, Ryan F, Seoighe A, Santos-Martinez MJ, Ryan C, Gilmer JGF. Management of iron deficiency in women of childbearing age with oral iron intolerance: a prospective, randomised, controlled trial of three doses of an iron-whey-protein formulation : Prospective RandomisEd study of women of Childbearing age with gastroInteStinal Intolerance to Oral iroN (PRECISION). Int J Clin Pharm. Published online December 26, 2023. doi:10.1007/s11096-023-01640-7
  2. Anaemia in women and children. World Health Organization. Accessed January 15, 2024.