Metformin Sr (Metformin Hydrochloride)

Metformin Sr belongs to the biguanide class and is employed in the management of disorders related to glucose metabolism.

• Type 2 diabetes mellitus: improves glycaemic control by reducing hepatic glucose output and enhancing peripheral insulin sensitivity.
• Impaired glucose tolerance: helps delay progression to overt diabetes when used as part of lifestyle intervention.
• Polycystic ovary syndrome (off‑label): may improve insulin resistance and restore ovulatory function.

• Metformin Hydrochloride acts primarily by inhibiting mitochondrial respiratory‑chain complex I, which reduces hepatic gluconeogenesis. It also increases AMP‑activated protein kinase activity, enhancing peripheral glucose uptake and utilization while decreasing intestinal glucose absorption, collectively lowering circulating blood glucose levels.

Metformin Sr may cause a range of adverse reactions, most of which are mild and transient.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Diarrhoea: loose stools, often early in therapy.
• Abdominal discomfort: cramping or bloating.
• Metallic taste: transient alteration of taste perception.
• Loss of appetite: reduced desire to eat.
• Flatulence: increased intestinal gas.

Serious or Rare Side Effects

• Lactic acidosis: rare but life‑threatening metabolic acidosis.
• Severe skin reactions: such as Stevens‑Johnson syndrome.
• Hypoglycaemia: when combined with other glucose‑lowering agents.
• Hepatic failure: impaired liver function may exacerbate toxicity.
• Renal impairment: accumulation leading to toxicity.
• Vitamin B12 deficiency: long‑term use may reduce absorption.

Before initiating Metformin Sr, several safety considerations should be observed.

• Renal function assessment: ensure adequate glomerular filtration rate before prescribing.
• Hepatic function monitoring: evaluate liver enzymes to reduce lactic acidosis risk.
• Lactic acidosis risk evaluation: avoid in patients with hypoxia, heart failure, or severe infection.
• Elderly patient caution: start with lower doses and monitor tolerance.
• Vitamin B12 status: consider periodic testing during long‑term therapy.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Metformin Sr can interact with several medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Iodinated contrast agents: may precipitate acute renal failure and lactic acidosis.
• Cimetidine: can increase metformin plasma concentrations.
• Alcohol excess: heightens risk of lactic acidosis.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: may mask hypoglycaemia symptoms.
• Diuretics: can affect renal clearance of metformin.
• ACE inhibitors or ARBs: monitor renal function and potassium levels.
• Warfarin: may require INR monitoring.
• Digoxin: observe for potential additive effects on renal function.