Enalaprilat
Vasotec IV
The active metabolite of enalapril, given directly intravenously. Rarely used in hypertensive crisis: onset is slow, duration 8–24 hours, and the effect varies widely between individuals because it is governed by plasma volume and renin activity.
Contraindicated in pregnancy — ACE inhibitors in the second and third trimester cause foetal harm and foetal death. A hypovolaemic or renin-stimulated patient may develop profound, prolonged hypotension from the starting dose.
Dosing in adults
| Indication | Regimen | Comment |
|---|---|---|
| Hypertensive crisis | 1,25 mg iv over 5 minutes | evaluate for at least 1 hour before dose increase |
| Repeated dosing | 1,25 mg iv every 6 hours | maximum dose 5 mg iv every 6 hours |
| Patient on diuretics | 0,625 mg iv as the first dose | high risk of marked blood pressure fall |
| Acute left ventricular failure | 0,625–1,25 mg iv | second-line choice, controllability is poor |
eGFR < 30 ml/min: starting dose 0,625 mg iv. Monitor potassium and creatinine.
No adjustment — enalaprilat is already the active form and requires no hepatic activation.
5–10 μg/kg iv every 8–24 hours. ACE inhibitors are avoided in neonates.
Wrong drug when the blood pressure needs to be readily reversible: duration is up to one day and effect is unpredictable. Avoid entirely in pregnancy, bilateral renal artery stenosis, and in acute myocardial infarction with threatened hypotension.
Pharmacokinetics
- ONSET
- 15–30 minutes
- PEAK EFFECT
- 1–4 hours
- DURATION
- 8–24 hours
- t½
- 35 hours (effective 11 hours)
- PROTEIN BINDING
- 50–60 %
- METABOLISM
- None — excreted unchanged
- EXCRETION
- Renal
- DIALYSIS
- Removed by haemodialysis