Generic Name

Binding:

Mechanism

• Binding: *Insulin Regular* binds to the insulin receptor (α‑subunits) on target cells (liver, muscle, adipose).
• Signal transduction: Receptor autophosphorylation activates the intrinsic tyrosine‑kinase activity → phosphorylation of IRS‑1, PI3K pathway.
• Metabolic effects:
• ↑ glucose uptake via GLUT‑4 translocation (muscle/ adipose).
• ↓ hepatic gluconeogenesis and glycogenolysis.
• ↑ glycogenesis and ↑ lipogenesis.
• Duration: Onset ~30 min (IV); peak 1–2 h; duration 4–6 h (short‑acting).

Pharmacokinetics

• Administration routes: Subcutaneous, intravenous (bolus or infusion).
• Onset:
• IV: ≤30 min (rapid).
• SC: 30–60 min (slow).
• Peak concentration: 1–2 h (IV) / 2–6 h (SC).
• Elimination: Insulin is degraded by peptidases (neprilysin, insulin‑receptor kinase); half‑life ≈30 min IV, 5–6 h SC.
• Protein binding: <10 %; unaffected by renal/hepatic impairment.

Indications

• Type 1 Diabetes Mellitus – basal‑bolus regimens.
• Type 2 Diabetes Mellitus – as part of mixed/long‑acting insulin combos or rapid titration.
• Diabetic ketoacidosis – IV insulin infusion.
• Hyperglycaemia in pregnancy – when rapid control needed.
• Pre‑operative glucose control in peri‑operative settings.

Contraindications

• Contraindicated:
• Hypoglycaemia (current or recent).
• Known hypersensitivity to bovine insulin or excipients.
• Warnings:
• Hypoglycaemia – requires frequent monitoring; adjust dose if glucose <70 mg/dL.

‑ Hypersensitivity reaction – anaphylactoid responses reported.

‑ Hyperkalemia risk in renal disease (insulin drives K⁺ into cells).
• Non‑diabetic hyperglycaemia – use cautiously; monitor renal function.

Dosing

• Initial dose (IV infusion): 0.15–0.2 U/kg/hr (2 U/h for 70 kg patient).
• SC dosing:
• Children < 10 y: 0.5–1 U/kg/day (split 1/4‑1/2‑1/4).
• Adults: 0.5–1 U/kg/day (split ¼‑½‑¼).
• Titration: Adjust by 2–4 U twice daily based on 4‑hour post‑meal glucose.
• Short‑acting infusion: 0.1–0.25 U/kg/h; target glucose 100–180 mg/dL.
• Storage: Refrigerated (2–8 °C) if used before reconstitution; after reconstitution, keep at 4–8 °C, discard after 28 d.

Adverse Effects

• Common:
• Hypoglycaemia (most frequent).
• Injection‑site reactions: erythema, edema, lipodystrophy.
• Minor nausea/vomiting (rare).
• Serious:
• Severe hypoglycaemia/neurologic sequelae.
• Anaphylaxis (rare).
• Hypokalemia/arrhythmias secondary to insulin‑induced K⁺ shift (especially in renal failure).
• Accumulation in hepatic/renal dysfunction → prolonged hypoglycaemia.

Monitoring

• Blood glucose: Capillary BG 4–6 h post‑dose; continuous glucose monitoring if available.
• Serum potassium: Daily if on high‑dose insulin or renal impairment.
• A1C: Every 3 months to assess long‑term control.
• Weight/BMI: Weight gain may indicate excessive dosing.
• Liver & kidney panels: Baseline & periodically for high‑dose therapy.

Clinical Pearls

• Rapid‑acting substitution: Regular insulin can serve as a “bridge” before long‑acting analogs are available for titration.
• Injection‑site rotation: Use 3 cm away from previous site; avoid lipohypertrophy that blunts absorption.
• Bolus‑in‑to‑bolus titration: In DKA, add 10 U bolus if BG >400 mg/dL before starting infusion.
• Avoid food after IV insulin: Causes rapid hypoglycaemia; schedule meals 2–3 h after infusion start.
• Syringe vs. pen: Pens deliver precise 0.1 U increments; syringes may lead to dosing error; prefer pens for outpatient basal‑bolus regimens.
• Switching between species: Bovine insulin reacts with bovine antibody; consider human‑derived analog when prolonged use is intended.
• In pregnancy, use low‑dose, timed basal for strict glucose targets (70–110 mg/dL).

> Key takeaway: *Insulin Regular* remains the cornerstone for rapid glucose control but requires vigilant glucose monitoring, proper injection technique, and dosage adjustments tailored to renal/hepatic status to avoid hypoglycaemia and other serious AEs.