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Insulin Glargine (Lantus)
Insulin glargine, marketed under the brand name Lantus, is a long-acting basal insulin analog used to manage both type 1 and type 2 diabetes mellitus. Designed to mimic physiological basal insulin secretion, it provides a steady, peakless glycemic control over 24 hours. This article synthesizes evidence from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to detail its mechanism of action, clinical uses, dosing, side effects, precautions, drug interactions, and pharmaceutical nomenclature.
Insulin glargine functions by:
- Binding to Insulin Receptors: Facilitates glucose uptake into skeletal muscle and adipose tissue while suppressing hepatic glucose production.
- Modified Pharmacokinetics:
- Forms microprecipitates at the subcutaneous injection site, slowly releasing insulin into the bloodstream.
- Provides a flat, peakless profile with an onset of 1–2 hours and duration of 18–24 hours (Lippincott).
- Mimics endogenous basal insulin, reducing fasting and between-meal hyperglycemia (Lange).
- BNF-Approved Indications:
- Type 1 Diabetes: Basal insulin component in basal-bolus regimens.
- Type 2 Diabetes: Monotherapy or combined with oral agents/GLP-1 agonists when oral therapies fail.
- Gestational Diabetes: Use under specialist supervision if lifestyle modifications fail (BNF).
- Off-Label Uses:
- Prediabetes in high-risk individuals (limited evidence).
- Initial Dose:
- Type 1 Diabetes: 0.2–0.4 units/kg/day, adjusted based on blood glucose.
- Type 2 Diabetes: 10 units daily or 0.1–0.2 units/kg/day (BNF).
- Administration:
- Subcutaneous injection once daily at the same time (typically bedtime).
- Rotate injection sites (abdomen, thigh, or deltoid) to prevent lipodystrophy.
- Renal/Hepatic Impairment:
- Reduce dose in severe impairment; monitor glucose closely (Lange).
- Unopened vials/pens: Refrigerate (2–8°C).
- In-use devices: Store at room temperature (≤25°C) for up to 4 weeks (BNF).
- Hypoglycemia: Most frequent, especially with dose errors or missed meals.
- Injection Site Reactions: Pain, lipodystrophy, or erythema.
- Weight Gain: Moderate (2–4 kg) due to anabolic effects (Lippincott).
- Rare but Serious:
- Hypersensitivity: Rash, angioedema.
- Hypokalemia: Insulin shifts potassium intracellularly; monitor in at-risk patients (BNF).
- Contraindications: Hypersensitivity to insulin glargine or excipients.
- Regular blood glucose and HbA1c checks.
- Assess renal/hepatic function periodically (Lange).
- Hypoglycemia Risk Enhancers:
- Beta-Blockers: Mask hypoglycemia symptoms (e.g., tachycardia).
- Sulfonylureas, GLP-1 Agonists: Synergistic effects.
- Hyperglycemia Inducers:
- Corticosteroids, Thiazides: Counteract glucose-lowering effects (BNF).
- Other Interactions:
- ACE Inhibitors, Lithium: May alter insulin requirements (Lippincott).
- Generic Name: Insulin glargine.
- Brand Names:
- UK (BNF): Lantus®, Abasaglar® (biosimilar).
- US: Lantus®, Basaglar® (biosimilar), Toujeo® (U300 concentrated formulation).
