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Pharmacology · Drugs and Prescriptions

Metformin

Metforminum

Metformin (Metforminum) is an oral hypoglycemic agent belonging to the biguanide group, classified among metabolic regulators. The main pharmacological feature of the drug is that it does not stimulate insulin secretion, but rather increases tissue sensitivity to it.

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Presentation0.5 g tablets
GroupBiguanides (metabolic regulators)
AdministrationOrally, 2–3 times a day during or after meals
Severe adverse effectLactic acidosis
How to write a prescription
Rp.: Tab. Metformini 0,5
D.t.d. N 60
S. Внутрь по 1 таблетке 2–3 раза в день во время или после еды

Alternative prescription notations: Tabulettas Metformini 0.5; Tab. Metformini hydrochloridi 0.5; Tab. Metformini 0.85

Dosage form
Tabs. 0.5 g
Administration
Orally 0.5 g 2–3 times a day during or after meals
Group
Agents regulating metabolic processes
4 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Classification of hypoglycemic agents

To systematize drugs used in type 2 diabetes mellitus, they are categorized by their effect on insulin secretion.

There are endogenous insulin incretion (secretion) stimulators, whose action is based on enhancing hormone production by pancreatic $\beta$-cells. These include sulfonylureas, meglitinides, and incretin mimetics (GLP-1 receptor agonists and DPP-4 inhibitors).

Metformin (the primary representative of the biguanide group) differs fundamentally from them: its hypoglycemic effect is not associated with the stimulation of insulin secretion. Historically, buformin and phenformin were also part of the biguanide group, but they are currently excluded from clinical practice. Well-known brand names of metformin include Glucophage, Siofor, and others.

Mechanism of action

The detailed mechanism of action of metformin is not fully understood, but both peripheral and central effects have been proven. The following key components are distinguished:

  1. Sensitization: increasing the sensitivity of insulin-dependent tissues to endogenous insulin.
  2. Muscle tissue: stimulation of glucose uptake by skeletal muscles (myocytes).
  3. Liver: reduction of glucose production by hepatocytes.
  4. Gastrointestinal tract: reduction of intestinal glucose absorption.
  5. Glucose utilization: stimulation of anaerobic glycolysis.
  6. Hormonal profile: reduction of blood glucagon levels.
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Clinical application and combination therapy

Metformin is used in two main regimens:

  • Monotherapy.
  • Combination therapy. The drug combines excellently with other hypoglycemic agents to achieve target glucose levels.

Common clinical combinations:

  • With GLP-1 receptor agonists (e.g., exenatide).
  • With sulfonylureas.
  • With DPP-4 inhibitors (gliptins). Fixed combination products exist: «Janumet» (sitagliptin + metformin) and «Galvus Met» (vildagliptin + metformin).

Side effects

Although the biguanide group as a whole is characterized by good tolerability, adverse reactions are possible with metformin intake and are divided into two categories:

1. Dyspeptic disorders (most common) Include nausea, vomiting, diarrhea, flatulence, and abdominal pain. Clinical significance: these conditions are not life-threatening, but they cause discomfort and often limit the use of the drug (reduce compliance).

2. Lactic acidosis (specific and severe effect)

  • Pathogenesis: directly caused by the drug's mechanism of action. Metformin stimulates anaerobic glycolysis, the end product of which is lactic acid (lactate). Its excessive accumulation leads to a shift in blood pH.
  • Symptoms: manifested by weakness, drowsiness, myalgia, dyspnea, hypothermia, and bradyarrhythmia. Requires immediate medical attention.

Prescription writing rules

According to the prescription reference guide, the drug is prescribed in tablet form.

  • Presentation: Tabs. 0.5 g.
  • Dosing regimen: Orally, 0.5 g 2–3 times a day.
  • Relation to meals: Take during or after meals (this recommendation helps minimize the risk of dyspeptic disorders).

Briefly: answers to topical questions

What are the contraindications for prescribing metformin?

Contraindications to prescribing metformin include a number of severe pathological conditions and diseases. These include:

  • Renal impairment — at an estimated glomerular filtration rate below 30 mL/min/1.73 m².
  • Liver failure.
  • Acidosis of any etiology — including diabetic ketoacidosis.
  • Acute coronary syndrome.
  • Conditions associated with hypoxia — any states accompanied by oxygen deprivation.
  • Vitamin B12 deficiency anemia.
  • Alcoholism.
  • Pregnancy and lactation.

In addition, drug intake should be discontinued 48 hours before and after major surgeries, as well as procedures involving intravenous administration of iodine-containing radiocontrast agents.

What brand names (synonyms) does metformin have?

Metformin is available on the pharmacological market under several brand names as monotherapy and fixed combinations. The following synonyms of the drug are known:

  • Single-ingredient drugs — Glucophage, Siofor, and others.
  • Combination forms — «Janumet» (includes sitagliptin and metformin) and «Galvus Met» (includes vildagliptin and metformin).
How to memorize

Metformin acts like a strict coach: it forces muscles to consume glucose (uptake), prohibits the liver from producing it, switches cells to oxygen-free respiration (anaerobic glycolysis -> lactate), while leaving the pancreas untouched.

Class and exam questions

Does metformin cause depletion of pancreatic beta cells?

No. Unlike sulfonylureas or meglitinides, metformin does not stimulate the secretion of endogenous insulin by beta cells, but merely increases tissue sensitivity to it.

Why can lactic acidosis develop when taking metformin?

One of the drug's mechanisms of action is the stimulation of anaerobic glycolysis. The end product of this biochemical process is lactic acid, the accumulation of which in the body causes acidosis.

Which drugs are appropriate to combine with metformin?

It is often prescribed together with sulfonylureas, GLP-1 receptor agonists (exenatide), or DPP-4 inhibitors (sitagliptin, vildagliptin) for comprehensive glucose control.

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What else to study on this topic

  • Sulfonylureas and their effect on pancreatic beta cells.
  • Incretin mimetics: comparison of GLP-1 agonists (exenatide) and DPP-4 inhibitors (gliptins).
  • Meglitinides (nateglinide) and mechanisms of postprandial hyperglycemia control.
  • Alpha-glucosidase inhibitors (acarbose) and intestinal carbohydrate fermentation.
  • Pathophysiology of lactic acidosis: causes, symptoms, and emergency care.

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