Insulin aspart
NovoRapid · Fiasp · Insulin aspart Sanofi · Kirsty
The mealtime insulin in Swedish healthcare and simultaneously the insulin used for intravenous infusion in diabetic ketoacidosis and hyperosmolar hyperglycaemic state. Subcutaneously it has an onset within 10–20 minutes and a duration of 3–5 hours; intravenously the half-life is a few minutes, which makes the infusion fully controllable but also means the effect ceases within minutes if the drip stops. Always clearly distinguish the subcutaneous from the intravenous regimen — they have no dose relationship.
Hypoglycaemia is the dose-dependent toxicity and can be life-threatening. The unit abbreviation must never be written as U or IE in handwritten prescriptions — misinterpretation produces a tenfold overdose. During intravenous infusion in ketoacidosis, plasma potassium must be known and at least 3,3 mmol/l before insulin is started; insulin drives potassium intracellularly and can trigger life-threatening hypokalaemia with arrhythmia.
Dosing in adults
| Indication | Regimen | Comment |
|---|---|---|
| Mealtime insulin, subcutaneous | Total daily dose 0,3–0,5 units/kg at initiation, of which approximately half as mealtime doses distributed across breakfast, lunch, and dinner | given 0–10 minutes before the meal (Fiasp at the start of the meal) |
| Correction dose, subcutaneous | (current plasma glucose − target) divided by the insulin sensitivity factor, where the factor ≈ 100 divided by total daily dose | at least 3 hours between corrections, otherwise the effects stack |
| Diabetic ketoacidosis, intravenous | 50 units in 50 ml sodium chloride 9 mg/ml (1 unit/ml) in a syringe, infusion 0,1 units/kg/hour without bolus | potassium ≥ 3,3 mmol/l first; glucose 100 mg/ml 75–125 ml/hour when plasma glucose < 12–15 mmol/l |
| Hyperosmolar hyperglycaemic state | Fluids first; insulin infusion 0,05 units/kg/hour when plasma glucose has stopped falling on fluids alone | lower plasma glucose and osmolality slowly, at most 3–4 mmol/l per hour |
| Acute hyperkalaemia | 10 units iv together with 25 g glucose (e.g. 50 ml glucose 500 mg/ml) | check plasma glucose after 30 and 60 minutes |
Insulin requirements fall when eGFR drops below 60 ml/min and markedly below 30 ml/min — insulin is partly eliminated renally. No fixed percentage; reduce the dose stepwise and increase glucose monitoring frequency. Remains usable in dialysis.
Insulin requirements are unpredictable: reduced gluconeogenesis and depleted glycogen stores lower requirements, while insulin resistance in steatosis raises them. No fixed dose adjustment — titrate against measurements.
Same weight-based principles as in adults. In ketoacidosis in children, insulin infusion is 0,05–0,1 units/kg/hour and never as a bolus, and fluids are given more slowly because of the risk of cerebral oedema — follow the paediatric unit protocol.
Do not give the subcutaneous mealtime dose as a substitute for insulin infusion in ketoacidosis — absorption is unreliable in the dehydrated and peripherally cold patient. The most common serious mistake is the reverse: stopping the infusion when ketoacidosis has resolved without giving subcutaneous basal insulin at least one hour before, causing the patient to re-ketose within a few hours.
Pharmacokinetics
- ONSET (SC)
- 10–20 minutes
- PEAK EFFECT (SC)
- 1–3 hours
- DURATION (SC)
- 3–5 hours
- t½ (SC)
- approximately 1,5 hours
- t½ (IV)
- a few minutes
- DEGRADATION
- Insulin receptor-mediated in liver, kidney, and muscle
- EXCRETION
- Renal (peptide fragments)
- STRENGTH
- 100 units/ml