Pharmacodynamics and absorption characteristics
The base substance of the drug is iron(II) sulfate heptahydrate ($FeSO_4 \cdot 7H_2O$). Its main pharmacological feature is that it contains ferrous ionized iron ($Fe^{2+}$). This specific valence state is critically important for absorption: ferrous iron ($Fe^{2+}$) is characterized by a high degree of absorption in the gastrointestinal tract compared to ferric iron.
Despite the good bioavailability of the ion itself, in modern clinical practice Ferrosi sulfas is rarely used as monotherapy. To achieve maximum therapeutic effect, it is included in combination medicinal forms.
Combination drugs (absorption modification)
To increase therapy efficacy and improve absorption, iron sulfate is combined with special adjuvants. Depending on the additive, several classical combinations are distinguished:
- With ascorbic acid (using the drug Ferroplex as an example). Ascorbic acid acts as a reducing antioxidant. It prevents iron oxidation by reducing ferric iron ($Fe^{3+}$) back to ferrous iron ($Fe^{2+}$), which is absorbed much better by the intestinal mucosa.
- With surfactants (using the drug Conferon as an example). Sodium dioctyl sulfosuccinate is added to the composition. This surfactant reduces surface tension, which facilitates the contact of iron ions with the mucosa and accelerates their absorption.
- With mucoprotease and ascorbic acid (using the drug TardYferon as an example). The addition of the enzyme mucoprotease further increases the bioavailability of iron ions in the gastrointestinal tract.
Prolonged-release forms
To maintain a stable concentration of iron in the blood and reduce irritant effects on the gastrointestinal tract, modified-release forms have been developed.
A prime example is Fero-Gradumet. In this form, iron sulfate is integrated into a special polymer matrix (gradumet sponge). Such a structure ensures the gradual, metered release of the active substance and its uniform absorption over several hours.
Indications and role in anemia therapy
Iron sulfate-based drugs are strictly indicated for hypochromic (iron deficiency) anemias — conditions characterized by decreased hemoglobin synthesis due to a lack of building substrate.
Important for differential therapy: Ferrosi sulfas is completely ineffective and is not used in hyperchromic anemias (in particular, megaloblastic anemia). These anemias are characterized by an increased color index and excessive saturation of erythrocytes with hemoglobin against the background of impaired cell division.
- In $B_{12}$-deficiency anemia, the drug of choice is Cyanocobalamin.
- In folate deficiency states, Folic acid is prescribed.
- In anemia of chronic disease or renal failure, Erythropoietin is used.
Sample prescription
The drug is available as a powder for oral administration. The standard single dose is 0.3–0.5 g.
Example of prescribing the powder: ```latin Rp.: Ferrosi sulfatis 0,3 D.t.d. N. 20 S. Take 1 powder orally 3 times a day. ```
Briefly: answers to topical questions
What gastrointestinal side effects are characteristic of iron sulfate?
The following adverse gastrointestinal reactions occur with the use of iron preparations:
- Dyspeptic disorders — anorexia, nausea, vomiting, abdominal pain, metallic taste in the mouth.
- Constipation — iron binds to hydrogen sulfide, which is a peristalsis stimulant, thereby reducing intestinal motility.
- Diarrhea — occurs in approximately 20% of patients and requires symptomatic therapy.
- Gastric irritation — nausea and epigastric discomfort, which can be minimized by taking the drug with meals.
With which medications is it not recommended to take iron sulfate due to impaired absorption?
Due to reduced absorption, iron sulfate is not recommended to be taken concomitantly with enterosorbents, including activated charcoal: they inhibit the absorption of medicinal substances through surface binding.
What are the absolute contraindications to the use of iron sulfate?
Contraindications to the prescription of enteral iron preparations include:
- Hemolytic anemia — the problem is not related to iron deficiency.
- Liver and kidney diseases.
- Inflammatory and ulcerative lesions of the gastrointestinal tract: peptic ulcer disease, ulcerative colitis, chronic inflammations — due to the risk of mucosal irritation.
"Birds of a feather flock together, but iron is FERROUS": the sulfate contains specifically Fe2+, which is absorbed in the gastrointestinal tract. Ascorbic acid "saves" the iron, preventing it from turning into the ferric state (oxidizing).
Class and exam questions
Why is iron sulfate rarely prescribed as monotherapy?
To increase bioavailability and improve absorption in the gastrointestinal tract, it is more appropriate to combine it with adjuvants: ascorbic acid, mucoprotease, or surfactants.
What role does ascorbic acid play in combination iron preparations?
It acts as a reducing agent, converting ferric iron (Fe3+) into ferrous iron (Fe2+), which has a significantly higher absorption rate.
Can megaloblastic anemia be treated with iron sulfate?
No. Megaloblastic anemias are classified as hyperchromic; they involve impaired DNA synthesis rather than hemoglobin synthesis. The drugs of choice here are cyanocobalamin (vitamin B12) and folic acid.
How does the "gradumet" form work?
It is an inert polymer sponge impregnated with iron sulfate. It ensures the gradual release of iron ions in the gastrointestinal tract over several hours.
What else to study on this topic
- Iron metabolism in the body: absorption, transport (transferrin), and storage (ferritin).
- Pharmacokinetic differences between ferrous (Fe2+) and ferric (Fe3+) iron.
- Differential diagnosis of hypochromic, normochromic, and hyperchromic anemias.
- Pharmacology of erythropoiesis stimulants: cyanocobalamin, folic acid, erythropoietin.
- Interaction of iron preparations with food and other drugs in the gastrointestinal lumen.
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