Mechanism of action and pharmacokinetics
Upon exogenous administration, Acidum folicum undergoes biological activation. In the liver, the drug is converted into its active form — tetrahydrofolic acid. It acts as a coenzyme and a donor of methyl and formyl groups, ensuring the transfer of one-carbon fragments in biosynthesis reactions.
Folates are critically necessary for the synthesis of purine and pyrimidine bases, nucleotides (adenine, guanine, thymidylate), as well as for amino acid metabolism (methionine, serine, homocysteine). This triggers processes of normal cell proliferation and DNA and RNA synthesis.
Pharmacological effects
The main effect of the drug is antianemic action. Folic acid stimulates erythropoiesis, regulating the maturation of megaloblasts and normoblasts, and improves iron absorption in the gastrointestinal tract.
The physiological role of the vitamin also consists in ensuring normal cell division, which is especially important during periods of increased body demand (e.g., pregnancy) and intensive tissue growth.
Clinical application (Indications)
The drug is prescribed for the prevention and treatment of hypovitaminosis and avitaminosis, as well as in the following pathological conditions:
- Macrocytic hyperchromic anemia (folate-deficiency anemia).
- Megaloblastic $B_{12}$-deficiency anemia (strictly in combination with cyanocobalamin).
- Leukopenia and other types of anemia.
- Complex therapy of oncological, neurological, and gastroenterological diseases, as well as to reduce toxicity in tuberculosis treatment.
- Specific prevention of hyperhomocysteinemia.
Side effects and safety profile
When using folic acid, the safety profile is quite favorable, though allergic reactions are possible.
A critically important safety aspect is the restriction on monotherapy: in pernicious ($B_{12}$-deficiency) anemia, it is forbidden to prescribe the drug in isolation. Although folic acid normalizes hematological blood parameters, it does not eliminate neurological symptoms, which allows severe neurological disorders to progress unhindered.
Rules of prescription and administration
Acidum folicum is available as a powder and in 0.001 g tablets.
Route of administration — orally (per os). The standard therapeutic dosage is 0.005 g per day. The course of treatment for deficiency states is usually 20–30 days.
Briefly: answers to topical questions
Which medicinal products are folic acid antagonists?
Folic acid antagonists are drugs that affect various stages of folate metabolism. These include the following agents:
- Methotrexate — an antineoplastic antimetabolite and folic acid antagonist.
- Trimethoprim — a dihydrofolate reductase inhibitor.
- Pyrimethamine — a component of combination antifolate drugs, such as Fansidar.
- Sulfonamides — dihydropteroate synthase inhibitors; these include sulfadoxine and sulfalene.
- Triamterene — a medicinal factor causing folic acid deficiency.
- Sulfasalazine — a drug antagonist of folic acid.
Taking folic acid antagonists can be the cause of its deficiency.
Folic acid is like «foil» for DNA: it protects and builds the genetic apparatus of the cell, but vitamin deficiency immediately hits the blood (macrocytic anemia) and requires combination with B12.
Class and exam questions
What type of anemia develops with folic acid deficiency?
Macrocytic hyperchromic anemia associated with impaired DNA synthesis and erythroblast division.
Why must folic acid not be prescribed in isolation for pernicious anemia?
Isolated administration improves blood parameters but does not relieve neurological disorders in B12 deficiency, which can cause neurological disorders to progress.
Which medicinal products are folic acid antagonists?
Methotrexate, trimethoprim, triamterene, and pyrimethamine.
What else to study on this topic
- Folate metabolism and the role of dihydrofolate reductase
- Mechanisms of action of sulfonamides and trimethoprim as antifolate agents
- The relationship between folic acid metabolism and vitamin B12 (methionine synthase pathway)
- Pharmacotherapy of hyperhomocysteinemia
- Use of leucovorin (calcium folinate) as a «antidote» for methotrexate
Master the entire topic in the «Pharmacology» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on «Folic acid» and 5,304 other subject pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 116 video lessons on the subject
Other topics in the «Drugs and Prescriptions» section
Free video lessons: pharmacologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.