Generic Name

Humulin RU 500

Mechanism

• Insulin receptor stimulation – binds the β‑subunit of the insulin receptor, triggering the intrinsic tyrosine kinase activity.
• Metabolic effects –
• ↑ Hepatic glycogen synthesis and ↓ glycogenolysis
• ↑ Glucose uptake in adipose and skeletal muscle through translocation of GLUT‑4 transporters
• ↓ Gluconeogenesis and renal gluconeogenic enzyme activity
• Rapid onset – due to the low concentration of protamine and no suspension, absorption begins within 10–15 minutes and peaks at 30–60 minutes, providing swift post‑prandial glycemic control.

Pharmacokinetics

> *Reference:* FDA prescribing information, 2024; *UpToDate* “Rapid‑acting insulin analogs”.

Indications

• Type 1 diabetes mellitus – post‑prandial glucose excursions.
• Type 2 diabetes mellitus – adjunct to basal insulin or as part of basal‑bolus regimen, especially when rapid onset is required.
• Pre‑operative insulin therapy – rapid correction of hyperglycemia before surgery.
• Hyperglycemia in critical care – requires precise titration with rapid on‑set agents.

Contraindications

• Hypersensitivity to human insulin or any excipient.
• Concurrent use of insulin‑sparing drugs (e.g., metformin overdose) due to risk of lactic acidosis.
• Significant renal or hepatic impairment – can prolong hypoglycemia risk.
• Pregnancy and lactation – use only if benefits outweigh risks; available, pregnancy‑category B.
• Avoid intramuscular administration – risk of prolonged absorption and hypoglycemia.

Warnings:
• Severe hypoglycemia: Monitor glucose < 80 mg/dL.
• Weight gain is common; counsel on diet.
• Risk of hypoglycemia in nursing infants or patients with renal dysfunction; adjust dose accordingly.

Dosing

• Initial dose: 0.2–0.4 U/kg as a single pre‑meal injection.
• Titration:
• Adjust by 2–4 U increments every 3–5 days based on post‑prandial Glucose Self‑Monitoring.
• Maximum dose typically 20–30 U per meal.
• Mode: Subcutaneous injection (abdomen, thigh, or upper arm).
• Pre‑meal: 15 minutes before eating.
• Missed dose: Skip; do not double.
• Storage: 2–8 °C; maintain sterility. Do not freeze. Reconstitute with 0.9% saline if needed.

Example basal‑bolus regimen:

> *Reference:* Diabetes Care 2023 Consensus Panel.

Adverse Effects

Serious but rare:
• Severe hypoglycemia with neurologic sequelae if untreated.
• Allergic reactions including anaphylaxis.

Monitoring

| HbA1c | *Reference:* ADA Standards of Care 2024; *Glycemic Control Journal*.

Clinical Pearls

• Rapid onset advantage – Administer 15 min pre‑meal for best post‑prandial control; later administration yields delayed peak.
• Use in pregnancy – Humulin R is considered safe; monitor fetal growth and maternal glucose closely.
• Avoid intramuscular – Unlike NPH, intramuscular use can cause unpredictable absorption and prolonged hypoglycemia.
• Dose adjustment in renal impairment – Reduce total daily dose by 20–30 % to avoid hypoglycemia.
• Consider fixed‑ratio premixed insulin only if consistent 1:1 basal/bolus need; otherwise basal‑bolus with Humulin RU 500 is superior for flexibility.
• Storage tip – When traveling, keep in a temperature‑controlled case; do not expose to > 30 °C for > 2 h.
• Patient education – Emphasize injection site rotation to prevent lipohypertrophy; use a 31‑g needle for minimal discomfort.

*Stay current*: Check the latest FDA prescribing updates and ADA guidelines to adjust dosing thresholds and contraindications accordingly.

--
• *Prepared by:* Pharmacology Assistant

*Date:* 2026‑01‑02

*References:*
• FDA Drug Label: Humulin RU 500 (2024)
• ADA Standards of Care for Diabetes 2024
• UpToDate: Rapid‑acting insulin analogs