What type of iron supplement, ferrous sulfate (iron(ii) sulfate) versus ferrous fumarate, is needed to treat iron deficiency anemia?

From the Guidelines

Ferrous sulfate is the preferred initial treatment for iron deficiency anemia due to its lower cost and widespread availability, as stated by the most recent guidelines 1. When treating iron deficiency anemia, the choice between ferrous sulfate and ferrous fumarate depends on several factors, including patient tolerance, cost considerations, and local availability.

• Both ferrous sulfate and ferrous fumarate are effective for treating iron deficiency anemia, with comparable effectiveness when taken at equivalent elemental iron doses.
• The standard adult dose for ferrous sulfate is 325 mg (65 mg elemental iron) taken 2-3 times daily between meals with vitamin C to enhance absorption.
• Ferrous fumarate provides more elemental iron per tablet (33% vs 20% in sulfate) and may cause less gastrointestinal side effects in some patients, making it a good alternative for those who cannot tolerate sulfate.
• According to the British Society of Gastroenterology guidelines, the initial treatment of IDA should be with one tablet per day of ferrous sulphate, fumarate, or gluconate, with adjustments made if not tolerated 1.
• The most recent expert review from the AGA clinical practice update on management of iron deficiency anemia recommends that no single formulation of oral iron has any advantages over any other, with ferrous sulfate preferred as the least expensive iron formulation 1.
• Both medications should be taken for at least 3 months to replenish iron stores, even after hemoglobin normalizes, with common side effects including constipation, nausea, and black stools.
• Taking the medication with food can reduce stomach upset but may decrease absorption by 40-50%, and liquid formulations are available for patients who have difficulty swallowing tablets.

From the FDA Drug Label

16 HOW SUPPLIED Ferrous Sulfate Tablets are available as follows: Each tablet contains 324mg of ferrous sulfate, equivalent to 65mg of elemental iron, providing 362% of the U.S. recommended daily intake (RDI) of iron for adults and children 4 and older.

PRINCIPAL DISPLAY PANEL - 60 Tablet Bottle Label DYE FREE • GLUTEN FREEGENTLE ON THE STOMACH FERRETTSIRONSUPPLEMENT Ferrous Fumarate 325mg Small, Easy to Swallow TabletOne Tablet Daily 60 TABLETS

The choice between ferrous sulfate and ferrous fumarate for treating iron deficiency anemia depends on the amount of elemental iron needed.

• Ferrous sulfate contains 65mg of elemental iron per 324mg tablet 2.
• Ferrous fumarate contains an unspecified amount of elemental iron per 325mg tablet, but it is known that ferrous fumarate typically contains about 63mg of elemental iron per 200mg tablet, so the amount in a 325mg tablet would be roughly 101mg of elemental iron, though this exact value is not provided in the label 3. Since the amount of elemental iron in ferrous fumarate is not directly stated, and ferrous sulfate is explicitly described with its elemental iron content, ferrous sulfate can be considered for treating iron deficiency anemia based on the information given 2.

From the Research

Iron Supplements for Iron Deficiency Anemia

• Iron deficiency anemia is typically treated with oral iron supplementation, with ferrous sulfate being the most commonly prescribed drug due to its simplicity and low cost 4.
• Ferrous salts, such as ferrous sulfate, are efficacious but frequently cause gastrointestinal side effects 4, 5.
• Alternative iron formulations, such as iron protein succinylate, have been developed and shown to be equally effective in treating iron deficiency anemia with better tolerability profiles 5.
• A study comparing ferrous sulfate and iron protein succinylate found that both were effective in restoring hemoglobin, hematocrit, and erythrocyte levels, with no statistical differences between the two treatments 5.
• Ferrous fumarate is another option for treating iron deficiency anemia, and a study found that a combination ferrous fumarate product was more effective than a polysaccharide iron complex in increasing hemoglobin and serum ferritin levels 6.
• A retrospective study found that patients who switched from oral ferric to ferrous supplements experienced significant improvements in blood test values, with minimal side effects 7.

Comparison of Ferrous Sulfate and Ferrous Fumarate

• There is limited direct comparison between ferrous sulfate and ferrous fumarate in the provided studies.
• However, a study found that ferrous sulfate was effective in treating iron deficiency anemia, while another study found that a combination ferrous fumarate product was more effective than a polysaccharide iron complex 4, 6.
• More research is needed to directly compare the efficacy and tolerability of ferrous sulfate and ferrous fumarate in treating iron deficiency anemia.

Dosage and Administration

• The optimal dosage and administration of oral iron supplements are unclear, with some studies suggesting that lower therapeutic doses may be sufficient for managing iron deficiency anemia 5, 8.
• A randomized controlled trial found no significant difference between alternate day and daily iron administration in improving hemoglobin levels 8.