Metformina Dinerfene Laboratórios Azevedos – Indústria Farmacêutica (Metformin Hydrochloride)

Metformin is indicated for the management of type 2 diabetes mellitus, a chronic metabolic disorder characterized by insulin resistance and elevated blood glucose levels, and is used as part of a comprehensive therapeutic regimen that includes diet, exercise and other antidiabetic agents.

• Type 2 diabetes mellitus: improves blood glucose levels and reduces HbA1c when used as part of a comprehensive treatment plan.

• Metformin primarily inhibits hepatic gluconeogenesis by activating AMP‑activated protein kinase (AMPK), which reduces glucose production. It also enhances peripheral insulin sensitivity by increasing glucose uptake in muscle and adipose tissue and modestly decreases intestinal absorption of glucose, collectively contributing to lower plasma glucose concentrations.

Metformin is generally well tolerated, but several adverse reactions have been reported.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Diarrhea: frequent loose stools, especially during initiation.
• Abdominal discomfort: cramping or bloating.
• Metallic taste: transient alteration of taste perception.
• Weight loss: modest reduction in body weight.
• Vitamin B12 deficiency: decreased absorption with long‑term use.

Serious or Rare Side Effects

• Lactic acidosis: rare but potentially fatal metabolic acidosis.
• Severe skin reactions: such as Stevens‑Johnson syndrome.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Hypoglycemia: usually when combined with other glucose‑lowering agents.
• Anemia: due to reduced red blood cell production.
• Electrolyte imbalance: especially with prolonged diarrhea.

Metformin should be used with careful clinical monitoring.

• Renal function assessment: avoid or adjust dose in patients with impaired kidney function.
• Hepatic function monitoring: use cautiously in liver disease.
• Lactic acidosis risk: discontinue before radiologic contrast procedures.
• Elderly patients: start at low dose and titrate slowly.
• Heart failure: evaluate severity before initiation.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Metformin may interact with several medicines, requiring attention to avoid adverse outcomes.

Major Interactions (Avoid)

• Iodinated contrast agents: increase risk of lactic acidosis; withhold metformin before and after imaging.
• Cimetidine: can raise metformin plasma concentrations.
• Alcohol excess: potentiates lactic acidosis.
• Rifampicin: may reduce metformin effectiveness.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: may mask hypoglycemia symptoms.
• Diuretics: can affect renal clearance of metformin.
• ACE inhibitors/ARBs: monitor renal function and electrolytes.
• Other antidiabetic agents: risk of additive hypoglycemia.
• Thyroid hormones: may alter glucose metabolism.