Ferric Citrate (Monograph)

Brand name: Auryxia
Drug class: Phosphate-reducing Agents
Chemical name: 2-Hydroxy-1,2,3-propanetricarboxylic acid iron (III) hydrate
Molecular formula: C₆H₅FeO₇•nH₂O
CAS number: 2338-05-8

Introduction

Phosphate binder used to reduce the intestinal absorption of phosphates.¹

Uses for Ferric Citrate

Hyperphosphatemia

Reduction of serum phosphorus in patients with chronic kidney disease who are undergoing dialysis.^{1 4 5}

Ferric Citrate Dosage and Administration

Administration

Oral Administration

Administer orally in divided doses with meals.¹

Dosage

Adults

Hyperphosphatemia

Oral

Initially, 2 g 3 times daily.¹

Monitor serum phosphorus concentrations and titrate dosage at intervals of 1 week or longer in decrements or increments of 1–2 g daily as needed to maintain target serum phosphorus concentrations.¹

Average dosage of 8–9 g daily was required to control serum phosphorus concentrations in a clinical study.¹

Prescribing Limits

Adults

Hyperphosphatemia

Oral

Maximum 12 g daily.¹

Special Populations

No special population dosage recommendations.¹

Related/similar drugs

ferrous sulfate, sucralfate, Carafate, sevelamer, FeroSul, Venofer, Renvela

Cautions for Ferric Citrate

Contraindications

• Iron overload syndromes (e.g., hemochromatosis).¹

Warnings/Precautions

Iron Overload

Iron absorption from ferric citrate may lead to excessive elevations in iron stores, especially when IV iron is used concomitantly.¹ Elevations in serum ferritin concentrations and transferrin saturation (TSAT) observed in clinical trials.¹

Assess iron indices (e.g., serum ferritin and TSAT) prior to initiating ferric citrate and monitor iron indices during therapy.¹ Patients receiving IV iron may require dosage reduction or discontinuance of IV iron.¹

Accidental Iron Overdosage

Accidental overdosage of iron-containing preparations is a leading cause of fatal poisoning in children <6 years of age.¹ Keep out of reach of children.¹ Contact a clinician or poison control center immediately in case of accidental overdosage.¹

GI Inflammation or Bleeding

Clinical studies did not include patients with inflammatory bowel disease or active, symptomatic GI bleeding; safety not established in these populations.¹

Specific Populations

Pregnancy

Category B.¹

Use caution.¹ Requirements for vitamins and other nutrients are increased during pregnancy; effect of ferric citrate on absorption of vitamins and other nutrients not studied in pregnant women.¹ Iron overdosage may carry a risk for spontaneous abortion, gestational diabetes, and fetal malformation.¹

Effects on labor and delivery not known.¹

Lactation

Iron is distributed into milk in rats; breast-fed infants may be exposed to iron from the phosphate binder when ferric citrate is administered to nursing women.¹

Pediatric Use

Safety and efficacy not established in children <18 years of age.¹

Keep out of reach of children to prevent accidental iron overdosage; iron from ferric citrate can be absorbed systemically.¹

Geriatric Use

No apparent differences in tolerability or efficacy relative to younger adults.¹

Common Adverse Effects

Diarrhea,¹ nausea,¹ constipation,¹ vomiting,¹ cough.¹

Drug Interactions

Effects on GI Absorption of Drugs

Possible decreased bioavailability of orally administered drugs given concomitantly; no empiric data concerning avoidance of interactions between ferric citrate and most oral drugs.¹

Consider administering ferric citrate and any concomitant drugs at different times if reduced bioavailability would have a clinically important effect on safety or efficacy.¹ The spacing of doses depends on absorption characteristics of the concomitant drug (e.g., time to peak plasma concentration, formulation [i.e., immediate release or extended release]).¹

Consider monitoring clinical response and/or blood concentrations of concomitant drugs with a narrow therapeutic index.¹

Nutrients

No formal drug-food interaction studies to date.² (See Actions.)

Specific Drugs

Ferric Citrate Pharmacokinetics

Absorption

Formal pharmacokinetic studies not performed.¹ Changes in serum iron indices indicate iron from ferric citrate is systemically absorbed.¹

Stability

Storage

Oral

Tablets

20–25°C (may be exposed to 15–30°C).¹ Protect from moisture.¹

Actions

• Ferric iron binds dietary phosphate in GI tract, forming insoluble complex (ferric phosphate) that is excreted in feces.¹

• Reduces serum phosphate concentration in dose-dependent manner.^{1 2}

• Also alters serum iron indices, increasing ferritin, iron, and TSAT.¹

• Clinical data suggest ferric citrate does not affect serum concentrations of folate or vitamins A, B₁₂, D, E, or K.²

Advice to Patients

• Importance of adhering to instructions about diet.¹

• Importance of taking ferric citrate as directed with meals.¹

• Importance of instructing patients about any concomitantly used drugs that should be taken at a different time of day than when ferric citrate is taken.¹

• Potential for ferric citrate to cause discolored (dark) stools.¹

• Potential for ferric citrate to cause diarrhea, nausea, constipation, and vomiting.¹ Importance of reporting severe or persistent GI symptoms to clinician.¹

• Risk of fatal iron poisoning in children <6 years of age.¹ Importance of keeping ferric citrate out of reach of children.¹ Contact a clinician or poison control center immediately in case of accidental overdosage.¹

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.¹

• Importance of advising clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.¹

• Importance of informing patients of other important precautionary information.¹ (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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