ferrous sulfate
Apo-Ferrous Sulfate ◆, ED-IN-SOL, Feosol, Feratab, Fer-In-Sol, Fer-Iron, Fero-Grad-500 ◆, Fero-Gradumet, Ferospace, Ferralyn Lanacaps, Ferra-TD, Mol-Iron, Novoferrosulfa ◆, PMS Ferrous Sulfate ◆, Slow FE

Available forms
Available without a prescription. Ferrous sulfate is 20% elemental iron. Dried and powdered form (exsiccated) is about 30% elemental iron.
Capsules: 150 mg, 190 mg, 250 mg
Capsules (extended-release): 150 mg, 159 mg, 250 mg
Elixir: 220 mg/5 ml
Liquid: 75 mg/0.6 ml, 125 mg/ml
Syrup: 90 mg/5 ml
Tablets (exsiccated): 195 mg, 200 mg, 300 mg, 324 mg, 325 mg
Tablets (exsiccated, extended-release): 160 mg
Tablets (timed-release): 525 mg

Indications and dosages
 Iron deficiency. Adults: 100 to 200 mg elemental iron P.O. t.i.d. For extended-release capsules, 150 to 250 mg P.O. once or twice daily. For extended-release tablets, 160 to 525 mg once or twice daily.
Children ages 2 to 12: 3 mg/kg P.O. daily in three or four divided doses.
Children ages 6 months to 2 years: Up to 6 mg/kg P.O. daily in three or four divided doses.
Infants: 10 to 25 mg/day P.O. in three or four divided doses.
Elderly patients: May need higher doses because reduced gastric secretions and achlorhydria may lower capacity for iron absorption.

Pharmacodynamics
Hematinic action: Ferrous sulfate replaces iron, an essential component in the formation of hemoglobin.

Pharmacokinetics
Absorption: Absorbed from the entire length of the GI tract, but primary absorption sites are the duodenum and proximal jejunum. Up to 10% of iron is absorbed by healthy individuals; patients with iron-deficiency anemia may absorb up to 60%. Enteric coating and some extended-release formulas have decreased absorption because they’re designed to release iron past the points of highest absorption; food may decrease absorption by 33% to 50%.
Distribution: Transported through GI mucosal cells directly into the blood, where it’s immediately bound to a carrier protein, transferrin, and transported to the bone marrow for incorporation into hemoglobin. Iron is highly protein-bound.
Metabolism: Liberated by the destruction of hemoglobin but is conserved and reused by the body.
Excretion: Healthy people lose very little iron each day. Men and postmenopausal women lose about 1 mg/day, and premenopausal women about 1.5 mg/day. The loss usually occurs in nails, hair, feces, and urine; trace amounts are lost in bile and sweat.

Contraindications and precautions
Contraindicated in patients receiving repeated blood transfusions and in those with hemosiderosis, primary hemochromatosis, hemolytic anemia unless iron deficiency anemia is also present, peptic ulceration, ulcerative colitis, or regional enteritis. Use cautiously on long-term basis.

Interactions
Drug-drug. Antacids, aluminum-containing phosphate binders, cholestyramine, cimetidine, vitamin E: Decreases ferrous fumarate absorption. Separate doses by 1- to 2-hour intervals.
Chloramphenicol: Increases response to iron therapy. Monitor patient carefully.
Doxycycline: May interfere with ferrous fumarate absorption even when doses are separated. Avoid use together.
L-thyroxine: May decrease L-thyroxine absorption. Separate doses by at least 2 hours. Monitor thyroid function.
Levodopa, methyldopa: May decrease absorption of these drugs. Monitor patient carefully.
Penicillamine: Decreases penicillamine absorption. Separate doses by at least 2 hours.
Quinolones: May decrease quinolone absorption. Monitor patient closely.
Tetracycline: Inhibits absorption of both drugs. Give tetracycline 3 hours after or 2 hours before iron supplement.
Vitamin C: Increases iron absorption. May be used as a beneficial drug interaction.
Drug-herb. Black cohosh, chamomile, feverfew, gossypol, hawthorn, nettle, plantain, St. John’s wort: Decreases iron absorption. Discourage use together.
Drug-food. Cereals, cheese, coffee, eggs, milk, tea, whole-grain breads, yogurt: May impair oral iron absorption. Discourage use together.

Adverse reactions
GI: nausea, epigastric pain, vomiting, constipation, black stools, diarrhea, anorexia.
Other: temporary staining of teeth (with liquid forms).

Effects on lab test results
None reported.

Overdose and treatment
The lethal dose of iron is 200 to 250 mg/kg; fatalities have occurred with lower doses. Signs and symptoms may follow ingestion of 20 to 60 mg/kg. Between 30 minutes and 8 hours after ingestion, patient may experience lethargy, nausea, vomiting, green and then tarry stools, weak and rapid pulse, hypotension, dehydration, acidosis, and coma. If death doesn’t immediately ensue, symptoms may clear for about 24 hours. At 12 to 48 hours, symptoms may return, accompanied by diffuse vascular congestion, pulmonary edema, shock, seizures, anuria, and hyperthermia. Death may follow.
 Treatment requires immediate support of airway, breathing, and circulation. In conscious patient with intact gag reflex, induce emesis with ipecac; otherwise, empty stomach by gastric lavage. Follow emesis with lavage, using a 1% sodium bicarbonate solution, to convert iron to less irritating, poorly absorbed form (phosphate solutions have been used, but carry hazard of other adverse effects). Take abdominal X-ray to determine continued presence of excess iron; if serum iron levels exceed 350 mg/dl, deferoxamine may be used for systemic chelation.
 Survivors are likely to sustain organ damage, including pyloric or antral stenosis, hepatic cirrhosis, CNS damage, and intestinal obstruction.

Special considerations
• Drug may be taken with meals to minimize GI effects; maximum absorption will occur if drug is taken between meals.
• Ferrous sulfate blackens feces and may interfere with tests for occult blood in the stool; the guaiac test and orthotoluidine test may yield false-positive results, but the benzidine test is usually not affected.
• Iron overload may decrease uptake of technetium 99m and thus interfere with skeletal imaging.
• Drug may cause dark-colored stools.
• Drug may stain teeth.
Breast-feeding patients
• Iron supplements are commonly recommended for breast-feeding women; no adverse effects have been documented.
Pediatric patients
• Extended-release iron capsules or tablets usually aren’t recommended for children. Overdose may be fatal; treat immediately.
Geriatric patients
• Iron-induced constipation is common in elderly patients; stress proper diet.

Patient education
• Instruct patient not to crush or chew extended-release forms.
• Explain that patient may mix liquid forms in water or juice and may drink through a straw.
 ALERT Inform parents that as few as three tablets can cause serious iron poisoning in children.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use